Signs of Spring 5: Turkey Vultures!

Vultures at dusk

Photo by D. Sillman

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Almost every evening for the past two weeks Deborah and I have watched a flock of vultures circling over the trees just to the north and west of our house. Most nights there are only four or five birds in the flock, but one night there were over a dozen. Occasionally, one or two of the birds glide into the large silver maple tree at the northwest corner of my field. They land in the branches, flutter their wings to stabilize themselves, and then stay a couple of minutes before taking off again to re-join their companions in their steady circling around the area. A few nights ago, though, at least ten of the vultures landed in the silver maple and settled in for the night.

A flock of circling vultures (called a “kettle”) is an omen of great literary power. It foretells death or impending disaster or doom. Just the image we need while we are isolating in place away from the coronavirus! Actually, vultures are the biological cleanup crew for our ecosystems! We should all thank them for all of the carcasses they dispose of!

Some neat names associated with vultures: vultures just hanging around (on the ground or on tree perches) are called a “committee,” and vultures group feeding at a carcass (which apparently they do with great manners and social skills (see below)) are called a “wake.”

I wrote a blog about vultures back in 2014. Here is an update!

Photo by Dori Wikimedia Commons

The turkey vulture (Cathartes aura) is a bird that everyone knows and almost no one loves. They are a joy to watch soaring along in their great circles across the sky, but the closer you get to them the less majestic they seem! They are large birds (they weigh up to four pounds and have wing spans up to six feet) and are the most abundant and most widely distributed avian scavenger in the New World. They are easily recognized on the ground by their featherless, red heads and in the air because of their broad, “eagle-sized” wings that characteristically wobble just a bit (and are held in an upward “V” (for vulture?) shape) as they soar in great circles in the updrafts.

Turkey vultures are found all across southern Canada, the continental United States, Mexico, Central America, and down South America to Tierra del Fuego. Birds in the northern regions of this broad distribution migrate to warmer habitats in the winter while birds in the warmer to milder regions of this range stay in place all year round. The vultures in the northeastern United States tend to migrate to Florida or Texas, while birds in the northwestern United States migrate all the way down to South America possibly as far as Argentina. Migrating flocks can be extremely large (thousands of individuals!). Turkey vultures, though, cannot fly at night (they require the thermal updrafts generated by the heat of the day) and, so, each day along their migration routes they must seek out secluded roosts as evening approaches.

Hinckley, Ohio (a small town just south of Cleveland) celebrates the spring return of their turkey vultures with a “Return of the Buzzard” day on March 15. For the past fifty-seven years they have been greeting the returning flocks of turkey vultures as an important sign of spring. It makes more sense than Groundhog Day, that’s for sure (although it less aesthetically pleasing than House Cat Day!).

The turkey vulture is an extremely gregarious bird. They roost in large, communal groups in specific locations that may be used for many generations. During the day, smaller, foraging groups of turkey vultures may pause in the high branches of a tree or on the roof of an abandoned building. Actively foraging and flying turkey vultures assemble in great flocks that can rise together in circular paths in the thermals of the heated atmosphere.

Turkey vultures are very long-lived birds. Life spans up to 25 years have been recorded. They have few predators except for a “usual suspects” list of potential nest predators (raccoons, skunks, foxes, opossums, snakes, etc.). They are relatively timid birds who will, if challenged at a carcass by another scavenger (like an eagle or a black vulture), regurgitate their ingested materials for the challenger to consume. At a carcass, turkey vultures feed in an organized, individual manner. Turkey vultures waiting for their turn at the carcass are exhibiting a behavior called “queuing.” Turkey vultures respond to threats and danger primarily by vomiting on the source of the danger. Since their stomach contents are typically acidic slurries of dead animal flesh, this behavior is quite an effective deterrent against aggression.

Photo by M. Baird Wikimedia Commons

The impact of DDT on egg shell stability reduced the turkey vulture population slightly, but the banning of this pesticide has led to a completely recovered and, possibly, growing worldwide population. Potential lethal impacts of lead ingestion (from bullets and pellets in hunter-killed animals), though, are possible threats to turkey vultures. Turkey vultures have also been killed by farmers and ranchers out of concern that these carrion consuming birds will spread pathogens and diseases from carcass to carcass. The great efficiency of the turkey vulture’s digestive system, though, very effectively destroys ingested pathogens (turkey vulture fecal materials are completely free of any pathogenic organisms).

Turkey vultures use their extremely well developed sense of smell to locate a carcass. This is most unusual since most avian scavengers and birds of prey utilize vision to find their food. This reliance on scent detection explains why foraging turkey vultures soar at lower altitudes than other types of vultures, and it may also explain their “wobbling” behaviors in flight (this motion may increase their ability to detect and precisely locate a scent source). Use of scent also enables turkey vultures to find buried or cached carcasses that had been hidden by some terrestrial carnivore. The greater abundance of turkey vultures in open or semi-open landscapes is also probably related to their particular method of finding food. Highways all over North and South America have become prime foraging habitats for this species.

Turkey vultures have extremely weak feet and blunt talons. Thus, they are not able to readily kill prey or rip at a carcass with anything other than their sharp, curved beak. They also show a distinct preference for relatively fresh kills and will not readily consume rotting carcasses.

Turkey vultures mate for life, but upon the death of a partner an individual may take a new mate. Courtship behaviors include a “dance” involving raised wings and feet and long, following flights led by the male. Nests are located in individually selected locations not far from the pair’s communal roost. The term “nest” might actually be a bit of an exaggeration in describing the egg site for a turkey vulture. It is typically a site located on the ground (in a cave, hollow log or tree stump, or in a dense mass of vegetation) where soil and leaf litter and pieces of rotting wood have been pushed aside to make a spot for the one to three laid eggs. In a given area there will be relatively few specific locations that will suitable for a turkey vulture to build its nest. A chosen site, though, may be used for a decade or more. Both parents incubate the eggs and also the nestlings. Both parents feed the rapidly growing young. Incubation time is between 28 and 40 days, and nestling developments times are between 60 and 84 days. So, at a maximum, a reproducing pair of turkey vultures may spend over four months in intense breeding and rearing of their young.

Turkey vultures are not beautiful to look at, they make no beautiful songs (in fact they lack the organ of song generation (the syrinx) completely!), they eat dead animals, they smell bad, and if you get too close to one it will vomit on you (did I mention that they don’t make very good pets?). They are, though, beautifully adapted to their scavenger role in our ecosystems and have many good if not noble traits. They form lasting social and mating bonds, they are very good parents, and they have excellent “table” manners at a carcass!

 

 

 

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Signs of Spring 4: Natural History of the White Pine

Longfellow Trail (Cook Forest, PA). Photo by daveynin, Flickr

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A couple of years ago I was standing in Cook Forest in front of the “Longfellow Pine.” There was no marker or sign that told me that this was the Longfellow, but I inferred that it was from its astonishing height. It was really quite uncomfortable bending my neck so far back to look up the trunk of this tree!

The Longfellow Pine is over 180 feet tall and is estimated to be 300 years old. Nearby is the “Seneca Pine” which is “only” 172 feet tall but its incredible trunk diameter of four feet makes it easily the largest tree by volume in Pennsylvania. There are a number of other massively girthed white pines scattered about in the protected space of Cook Forest. One hundred and twenty of these pines are over 150 feet tall, and a few have been estimated to be over 500 years old! All of these trees, named or not, are spectacular examples of what a white pine can be and, also, what the white pines of our state once were.

The white pine is the tallest tree in the eastern North American forest.  It grows in a variety of conditions but was once an important component of the untouched forests of Western Pennsylvania especially along rivers and streams and in the soils that formed from sand and gravel out-washes generated by the last glaciers that touched the northern parts of our state. These locations reflect the preference of the species for moist yet well drained soils in which to grow.

White pine tree. Photo by J.S.Conn, Flickr

White pines regularly reach 100 feet in height but there have been a few especially vigorous individual trees that soared up and even over 200 feet. Trees that were 150 feet tall and 40 inches in trunk diameter were common in the virgin forests of America. White pines live for 200 to 450 or more years and can become because of their great heights and longevity dominant emergent trees in a canopy of hemlocks and hardwoods.

White pines typically grow in cool, moist climates and are most often found in forests intermixed with many other species of trees including red pine, northern red oak, red maple, eastern hemlock, chestnut oak, white oak and more. Pure stands of white pine (“pineries”) were never common even in the pre-settlement forests.  A potential pinery site needed to be “excessively well drained” in order to both provide the periods of time of high moisture needed for the growth of the white pine and also periods of extremely dry conditions that curtailed competition from other, less drought resistant tree species. Periodic fires in these seasonally very dry sites also help to remove potentially competing tree species that are less fire resistant than white pines.

White pine needles. Photo by S. Rae, Flickr

The pineries contained a relative small number of “dominant” trees (i.e. very old, very large individuals). They primarily consisted of large numbers of medium-large, 200 year old trees.  Individual variations in vigor and fitness and external, sculpting forces like wind and fire kept these pure stands of white pine in a dynamic equilibrium of stress and re-growth and, thus, sustained the pure white pine “climax” forest ecosystem.

The white pine was the most valuable timber tree in the virgin forests of America. Its great height and straight growth form was in great demand for ship masts. Large specimens of white pines were labeled in the colonial forests as property of the king and his Royal British Navy. The wood of the white pine is light but very long grained and strong.  It is both easily transported (the cut trees float very well!) and easily worked. It was the ideal wood for construction and served as the structural material for houses, factories, and other buildings of growing cities and towns of America. It was, in fact, called the “tree that built America.”

The white pine was never as abundant in Western Pennsylvania as the local myths and land sale advertisements claimed. It made up at most 15% of the forest cover and was especially concentrated in the moist soils along the rivers and streams and in the well-drained, gravely, glacial soils in the far north of the state. These were the trees that settlers clearing their land cut and sold first. Sufficient numbers of white pines on a property could go a long way to pay back land purchasing costs and could help to support a settler’s family during the difficult initial years of farming.

White pine seedlings grow best in full sunlight and, so, require breaks in the forest canopy in order to thrive. Its seedlings grow very slowly for their first two or three years but are then capable, after they have established an extensive root system, of rapid growth (up to three feet per year for 10 or 15 years!).  They then settle into a slower growth rate (a foot of height gain each year) for the remainder of their lives.

White pine grove. Photo by J.Mayer. Wikimedia Commons

White pine is both an early “pioneer” species in a forest succession sequence and, for those specimens that survive and reach their mature heights and girths, members of the “climax” forest at the end of the successional sequence.  Excessive shading by highly competitive hardwood species (like aspens, oaks, and maples) can eliminate the relative shade intolerant white pine from a site. Less intense shading by an over-story of birches or pitch pine, though, can allow some white pine individuals to grow sufficiently tall to reach high into the canopy.

White pine trees have both male and female flowers. The female flowers may form when a tree is as young as 5 or 10 years of age. Flowering is full, though, when a tree reaches twenty feet of height. The female flowers are found primarily in the upper crown of the tree on the ends of the branches. Male flowers are not formed until the tree is older and larger (12 to 24 inches in diameter!). The male flowers are very small (0.3 to 0.4 inches long) and are concentrated on the bases of new shoots in the lower crown of the tree. A white pine does not produce male flowers every year. Pollen production, then, is only an occasional occurrence for any give tree. Possibly, this, along with the relative locations of a tree’s male and female flowers and the asynchrony of a tree’s formation of its flowers (a tree forms its male flowers a week or more before its female flowers), is another mechanism to reduce the probability of self fertilization, and, thus, increase the genetic variability of the subsequent generation.

Pollen is released in May or June and is dispersed by the wind. Pollen grains that find a female flower slowly develop and do not accomplish fertilization until some thirteen months later! The female cones, then, with their seeds, develop and mature up through the August or September of this second year. Mature cones drop their seeds within the month of their maturation. Seeds may be dispersed 200 feet from the parental tree. Gray squirrels are a major cone/seed dispersing agent and are also responsible for extensive burying of white pine seeds. Good seed production occurs every 3 to 5 years. Insect infestations (like the white pine cone beetle) can drastically impair seed production.

The soil beneath a white pine is full of seeds and potential pine seedlings.  The seeds require a period of cold stratification before they can germinate. The characteristics of the seedbed for the germinating seed and the developing seedlings are quite important. Under shading over-stories, seeds will readily germinate and seedlings will grow and develop on both disturbed and undisturbed litter layers. In full sun, though, moist mineral soil, moist mosses, and/or a protective short grass cover are needed both for germination and seedling development. If the shading is too dense, though, seedlings will grow so slowly that they will be unable to out-compete other tree species.

White pine cone. Photo by Famartin, Wikimedia Commons

The cones and seeds of the white pine are food for many birds (including chickadees, nuthatches, pine warblers, pine grosbeaks, red crossbills, and yellow bellied sapsuckers) and mammals (including gray and red squirrels, and  many species of mice). Beaver and porcupines consume the bark of white pines, and white-tailed deer, snowshoe hares, and cotton-tailed rabbits eat its seedlings and saplings.

The white pine is affected by several hundred insects and over a hundred diseases. Most serious of these are the white pine weevil that kills an affected tree’s terminal growth shoot, and the introduced pine shoot beetle which affects many pine species including the white pine. Also, white pines can be severely damaged by the introduced, exotic fungus that causes white pine blister rust .

White pine blister rust is a fungus native to Asia that had become established in European pines by the nineteenth century. When, as Gifford Pinchot so succinctly put it, the “orgy of forest destruction” was finally ebbing here in North America in the early Twentieth Century, the clear cut  forests required extensive rehabilitation and replanting.  Seedlings of North American white pines that had been exported to Europe many decades before were re-imported from German nurseries as one part of this rehabilitation effort. These seedlings, though, were contaminated with the fungus that causes white pine blister rust. The rust then became established throughout the east and represents to this day a major threat to the overall health and potential survival of the white pine throughout its native range.

White pine seedlings under thinned red pines. Photo by E. Sagor. Flickr

In Cook Forest around the Longfellow Pine, there are very few white pine seedlings growing. The disrupted, fragmented forest around this iconic tree is full of a variety of hardwood species, but there are very few young white pine trees anywhere to be seen. The dense canopy cover has prevented substantial growth of the shade-intolerant pine seedlings and encouraged the survival of a broad array of white competitors.

Here is what I wrote about the trail that climbs up around the Longfellow Pine back in 2010 when Deborah and I hiked the Baker Trail from Freeport to the Allegheny Forest (the Longfellow Trail in Cook Forest is a very short part of the 140 mile Baker Trail):

The forest around us is dense, shady, and old. Many great hemlocks and white pines covered the hillside. Clusters of American beech and many young hemlocks grow under and around them. Occasionally, one or two hemlock or white pine trunks stand out from the crowd of trees. These trunks, often four or five feet in diameter just radiate age and an ecological gravitas even in the continuous tapestry of all of the other magnificent trees. Looking up the trunks of these giants we frequently couldn’t even see the upper branches through the canopy. These tall, straight trees seem to disappear up into the tangle of the upper branches and feel like they are going “up” forever. One white pine whose full trunk could be visualized was five feet in diameter and approximately 140 feet tall. There are other trees that are even more massive.

I remember hiking in this forest with my family when I was a very little boy 50  years ago. This area had been hit by a large windstorm in 1956 (there is a plaque that commemorates this storm up along the Forest Cathedral trail). These past 50 years have been a period of significant re-growth in these forests. One of the impressions that I retain from our 1960 hikes across this hillside was how open, and sunny many of the trails were.  These trails today are tree covered and shady. Many of them are lined with young hemlocks growing up under a standing cover of tall birches and red maples. Most if not all of these trees are components of the vigorous  forest re-growth and succession that was triggered by these severe 1956 storms.

The lack of white pine seedlings on the Longfellow Trail is important. The forest floor is dominated by ferns and mosses, and there are quite a few young hemlocks and beeches. The large, older trees are surrounded by these species and are sometimes hard to pick out in the dense under-story. The large trees along the trail are reaching or have surpassed their expected, natural life spans. A 400 year old white pine is quite old and is nearing its natural end, but the 500 year old white pines in this forest are really living on borrowed time!

It is possible that the attempt to keep this forest unchanged and unchanging so that the large trees could be seen and enjoyed by passing generations of nature lovers may have put this ecosystem on an unsustainable, and fatal trajectory. Even the wind event of 1956 didn’t open the forest for white pine seedlings. Maybe even then there were too few seeds or an inhospitable seed bed in which they might grow.

White pine. Photo by PumpkinSky. Wikimedia Commons

If we think about white pines in the wild here in the East we have to add up the pressures of insects and diseases (especially those exotic species for which the white pines have no evolutionary experience or protections) along with the huge population of browsing white-tailed deer and the loss of suitable seedbeds and seed germination sites through habitat disruption and soil and litter erosion. All of these factors may have synergistically come together to doom the wild existence of this once great tree species. White pines now mostly exist as domesticated trees throughout their once broad, natural range. They are grown on Christmas tree plantations and are frequently used as an ornamental trees in urban and suburban parks and lawns. The white pine has lost its wildness and, in this reduced condition, has much less a capacity for wonder or for generating ecological awe.

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Signs of Spring 3: Coyote America!

Coyote. Photo by D. Moss, Wikimedia Commons

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I first came in contact with coyotes in 1970 during my freshman year at Texas Tech. One of my professors had an on-going project examining coyote stomach contents that he hoped would result in a definitive assessment of their diet, and he asked for student help sorting through a backlog of frozen, coyote stomachs. With the pay set at $1.75 an hour, how could I say no? So I worked for a couple of weeks in a windowless lab room all gloved and masked up, armed with a scalpel and forceps and learned to sort and eventually even recognize some of the bits and pieces of critters eaten by a coyote.

Stomach contents of a coyote. Public Domain.

Some of the stomachs were empty which indicted tough times out in our local coyote country, but most had bits of rabbit, various mice and other rodents, insect exoskeleton pieces, feathers and an odd mixture of plant leaves and stems. The project was sponsored by the state of Texas with the expectation, I think, that we would find nothing but raw mutton and wool in the stomachs. Local ranchers blamed every lamb loss and death on coyotes. I did not see any sheep residues, though, in any of the stomachs I dissected during the two weeks I worked on the project.

I found out later that after the project was completed there was very little evidence of any coyote predation on lambs or sheep. Also, I heard that the state and the local ranchers didn’t believe the results were accurate. Coyotes, they insisted, all evidence to the contrary ignored, were sheep killers.

Projects like this were carried out over and over all across the western plains, and the conclusions were almost always the same: coyotes eat rodents and rabbits and a strange mix of vegetation and detritus. They eat what is available. When they can, they will eat lambs and sheep, but they very seldom do so!

One of the most compelling observations in the aftermath of the decades of coyote extermination programs out west, in fact, was the declining quality of the range land for sheep and cattle. The arid grasslands were overrun with grass and seed eating rodents and rabbits leaving little forage available for domesticated grazing animals. Coyotes, in an incredibly unexpected way, since they were the prime predators of these grass and seed consumers, were actually good for sheep and cattle!

Again, the ranchers and the State of Texas did not want to hear any of this, and it took decades to get any of them to listen.

I just finished reading Dan Flores’ book “Coyote America.” The range of the discussion in the book is breathtaking: Flores describes myths in which coyotes are creator gods, or mischievous and incredibly “human” lesser deities. He goes through the science of coyotes as they lived in ecological equilibrium on the pre-European western plains. He discusses the propaganda and hysteria which labeled coyotes “arch-predators” in the increasingly settled west and explains how they become the focus of a “shock and awe” campaign of extermination. He describes coyotes as eventual (and maybe inevitable) survivors of these extreme programs, and then follows them in their migrations out of the Great Plains, driven by the very instincts and impulses that made them such a successful, plains and desert species. They hybridize with wolves along the way, and slip into urban ecosystems and increasingly intimate contact with their own modern day “arch” predator, human beings. And, amazingly, all along the way coyotes never lose their own unique, wild identity.

Photo by D. DeBold, Wikimedia Commons

Let’s picture coyotes in their pre-European, North American range: They were the small “prairie wolves” of the Great Plains and desert southwest. They scavenged wolf kills (of bison, deer or pronghorn) but mostly ate small prey like rodents, rabbits, prairie dogs, skunks, birds, insects, and were omnivorous enough to also consume, when available, a wide variety of plants and fruits. These broad food tolerances coupled with their ability to exhibit, at need, both “fission and fusion” behaviors (they could live alone or as mated pairs (fission) or form larger packs for protection and group hunting (fusion) depending on the dynamics and limiting factors of their environment). These behaviors combined with their innate furtiveness and caution and their ability to reproduce just to the carrying capacity of their ecosystems made them a very successful species under a wide range of conditions. They were also incredibly intelligent and could solve local food gathering and survival problems and communicate those solutions to their fellow pack members and even their offspring! Coyotes had a very robust cultural and species tradition!

Coyotes were bottled up in the plains primarily due to the large populations of surrounding, mountain and forest dwelling gray wolves. Modification of the North American landscape by Native American agriculture a thousand or more years ago (long before the mass arrival of Europeans) opened up many of these dense forests and allowed plains species (including bison and coyotes) to migrate into them. Coyotes encountered scattered populations of gray wolves that under the stress of depopulation and habitat change, instead of killing the invading coyotes mated with them. These hybridizations created the Algonquin wolf in Ontario and what was called until recently the “red wolf” of the southern United States. This “red wolf” is, in fact, genetically 80% coyote!.

Photo by R. Richardson. Wikimedia Commons

Six hundred years later, wolf populations were again exterminated this time by increasing numbers of colonizing Europeans. This allowed coyotes to again migrate out of the plains in almost all directions. When the Europeans turned their attention to the coyotes (who were in the post-gray wolf world the most obvious predator at hand to be hated) and began to try to exterminate them, the pressure on the coyote to move north, south, east and west became intense.

These migrating coyotes once again encountered scattered populations of gray wolves and the coyote/wolf hybrids from previous migrations. Once again, the wolves under their own ecological stresses of de-population and on-going extermination, mated with the coyotes instead of simply killing them. These matings added more coyote genes to the southern red wolf and created the large, eastern “coywolf”  hybrid in the north and east. The coyote/wolf matings and the formation of these hybrids allowed the coyotes to migrate across North America at a very rapid rate.

Coywolf. Photo by L.D.Mech, et al. Wikimedia Commons

So, there were coyotes and coyote hybrids all across North America. Coyotes historically had had an intimate relationship with humans and human towns and villages. The Aztecs, in fact, named a number of sections of their cities after the large numbers of coyotes that lived there, and the diaries and journals of early travelers across the plains mention the abundance (and audacious behaviors) of coyotes in the camps and settlements. Coyotes moving out of the plains, though, tended to inhabit areas that were more rural in nature primarily because of another canid that was loose and abundant in the larger cities and towns: domesticated dogs!

American cities prior to the late 19th Century had feral dogs and dog packs running freely through their streets and alleys. These dog packs aggressively attacked and killed any invading coyote (and many other species, too!) and very effectively kept coyotes out of urban areas. The initiation of dog control laws, dog catchers, dog pounds, etc. then effectively removed these anti-coyote forces and opened up urban ecosystem for the coyotes.

City-coyotes had many sources of food available to them: rats, deer (fawns mostly), geese, ducks, along with many exotic plants and fruits. There were also house pets (both cats and small dogs) and human trash, but analysis of urban coyote stomach contents indicate that both of these potential food sources make up a very small percentage of a typical urban coyote’s diet (less than 1 or 2 percent each!). Coyotes may kill cats and dogs because they recognize them as potentially competing predators, but, with some notable individual exceptions, do not generally take them as food. The absence of human garbage in the coyote diet is also very notable. The feral dogs that dominated the urban ecosystems for so many years thrived on garbage and human waste. Coyotes, though, are much more particular in their selection of food and have tended to stay within their broad range of “natural” food stuffs.

There are both biological and cultural section forces operating on urban coyotes. Coyotes are learning to move through the dense, busy city-scapes with fewer and fewer deaths due to cars. There may also be a selection for coyotes that are bolder and less shy around humans. There are also theories that “super genius” coyotes are being generated in the complex, urban environments, and predictions that these coyotes will have an increasingly large influence on future coyote/human interactions.

Photo by B. Matsubara, Wikimedia Commons

Coyotes are much safer in cities than in the surrounding countryside. In Chicago, for example, 61% of coyote pups survive while in nearby rural Illinois only 13% of the coyote pups survive. The tendency of coyote populations to grow to and then stabilize at the carrying capacity of their environment has led to urban coyotes to have smaller litters than their more rural counterparts. This drive to stable numbers has also led to the outward migration of excess individuals from the city ecosystems. Cities are serving, then, as the coyote brood chambers for the surrounding countryside.

We have coyotes here in Western Pennsylvania. My first Pennsylvania coyote was sitting beside a four-lane highway early one morning in June 2004 (I was driving my daughter up to State College for her college freshman orientation). A few years later I saw several coyotes running across a moonlit field in a half rural, half suburban township just south of here in Westmoreland County. Since then, my neighbors across the street have seen coyotes in their backyard, and this fall I spotted two coyotes hunting something late one afternoon in the thick brush on the banks of the Kiski River.

Coyotes are a part of our ecosystem now, and we need to learn to live with them because if history is any judge, we really don’t have any other options!

 

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The Pandemic: Some Things to Know About COVID-19

Photo by D. Sillman

COVID-19

I have had a number of people ask me about the coronavirus pandemic. I have put together this list of major points. If you have questions about COVID-19 please go to the most authoritative web sites for information and avoid the rest. The Center for Disease Control (CDC) and the World Health Organization (WHO) are the two best sites. I have also found that Johns Hopkins, the Mayo Clinic and Harvard Medical School sites were excellent places to find accurate information. Three secondary sites that have done a very good job of synthesizing and summarizing information on COVID-19 are the newsletter of the scientific journal Nature, the daily science news publication The Scientist, and The New York Times.

(the above picture, by the way, is me and my grandson, Ari, and my daughter Marian when we attended Joe and Marlee’s wedding this past December. Life is good!)

My summary:

  1. There are seven “coronaviruses” known to affect humans. Four of these infect cells in the upper respiratory tract and cause what we call the “common cold.” On average, people in North America get infected with these four corona viruses and “catch” colds three time a year.

The other three corona viruses (the “SARS” virus, the “MERS” virus and the new virus that causes COVID-19) cause much more serious, respiratory illnesses.

These viruses were named “corona” because of the protein projections off of the “body” of the virus making the virus look like a crown or like the corona of the sun.

The COVID-19 virus enters the mucosa cells of the respiratory tract via the ACE2 receptor protein (which are found on many types of body cells but which are very abundant on cells lining the lower respiratory tract)

Other organs of the body (whose cells also have the ACE2 receptor) may get infected with COVID-19 and may be damaged during the body’s vigorous immune response to the virus

  1. (the following is a synopsis of a March 12, 2020 article in the NYTimes that outlines the COVID-19 cycle in the human body):

When the virus enters a cell it hijacks the cell’s metabolic machinery and stimulates it to make many more copies of the virus. The viral load in the cell results in the cell’s death with the subsequent release of synthesized viruses and cellular debris. Immune system reactions to the infection generates first symptoms (sore throat, dry cough, fever, etc.)

These new viruses continue to spread down respiratory tract infecting more and more cells causing more and more severe symptoms. Infection of the cells in the lungs (bronchioles and alveoli) can lead to pneumonia.

NOTE: about 80% of individuals infected with the COVID-19 virus have mild symptoms (infection stays in the upper respiratory organs (it behaves like a common cold). 20% of infected individuals, though, get lower respiratory tract infections with much more serious symptoms. Approximately 2% of individuals infected with the COVID-19 virus die.

  1. A person infected with the COVID-19 virus will frequently cough and sneeze due to mucous membrane irritations caused by the virus. These sneezes and coughs will expel tiny droplets of water that are packed with viruses. These droplets can travel about 6 feet from the infected individual. This distance is the logic behind the idea of keeping one’s “social distance” when out in public.

(the following is from experiments conducted at the National Institute of Health (NIH)):

These droplets are relatively large and, so, will not stay suspended in the air for very long (but exactly how long this suspension lasts is not clear from experimental reports).

The viruses can remain viable in these droplets maintained in a laboratory-generated aerosol for about 3 hours.

Droplets landing on plastic or stainless steel surfaces may remain viable for 2 to 3 days

Droplets landing on a more porous surface (cardboard) remain viable for 24 hours

Droplets landing on fabric surfaces (like blankets?) are said to remain viable for even shorter periods of time according to the Mayo Clinic (but no experimental data was found to support this)

  1. Experiments at the Johns Hopkins Bloomberg School of Public Health (published in the Annals of Internal Medicine on March 10, 2020) indicated that people exposed to the COVID-19 virus, on average, began to show symptoms in 5.1 days. 97.5% of exposed patients showed symptoms within 11.5 days (hence the logic of a 14 day quarantine following exposure)
  2. A study at the Bundeswehr Institute of Microbiology (Munich Germany) recently released in a pre-print on Med Rxiv indicated that many of the examined COVID-19 patients had upper respiratory infections (and associated “common cold”-like symptoms). All infected patients, though, regardless of the mildness or severity of their symptoms, actively were producing and shedding viruses. The first five days with symptoms had the maximum rate of viral production and release, but viruses continued to be shed for up to one week after symptoms had abated.

 

  1. The most common way for the virus to be passed from an infected individual to a new host is via contact with the viral-laden droplets

Most of these transmissions are direct transfer of freshly expelled droplets to the mucous membranes (eyes, nose, mouth) of the new host. This requires close contact between the infected individual and the new host. In China most of the COVID-19 virus transfers were between infected patients and healthcare workers or between infected individuals and their family members.

Droplets from the respiratory tract of an infected individual may also be abundantly present on that individuals face. Hands and face touching , then, may be a mechanism to spread the virus from infected individuals to surrounding surfaces or to other individuals. Un-infected individuals may also transfer viral-laden droplets to their own eyes, noses or mouths via face touching. Face touching, then, is a mechanism for both spreading and indirectly infecting individuals with the virus!

DON’T TOUCH YOUR FACE!!!

  1. Soap: coronaviruses are encased in a lipid rich envelope. Soaps and detergents emulsify these fatty envelopes and very effectively kill the virus. Vigorous washing with soap is a very effective way to cut off hand dissemination or transmission of the virus (there is an excellent article in The Guardian (March 12, 2020) by Paul Thordarson called “The Science of Soap.”
  2. Disinfectants: surface disinfectants (alcohols, hydrogen peroxides and bleaches) are extremely effective at killing coronaviruses. These are tools that can cut down on the indirect spread of the viruses (but keep in mind that the DIRECT spread of viral droplets is the much more frequent pathway for infection!). For a very complete discussion of disinfectants and hand sanitizers see the March4, 2020 article by Compound Interest entitled “Corona virus: how hand sanitizers protect against infection.” Also note: hand sanitizers are very easy to use but washing your hands with soap is the most effective way to kill corona viruses!
  3. Death rates: in 2003 the SARS virus had a death rate of 10%

In 2012-2019 the MERS virus had a death rate of 23%

the 2019-2020 COVID-19 virus has a death rate of approximately 2%

COVID-19 is, apparently, much more easily transmitted than either the SARS or the MERS viruses and has infected many more people and already accounted for more deaths than both of these earlier viruses combined.

For comparison: the flu virus (which is a completely different virus from these coronaviruses) infects a very large number of people every year. The CDC estimates that last year 35.5 million people in the United States contracted flu. Of these 34,200 people died from flu or flu complications. That generates a death rate of approximately 0.1%.

  1. Examination of the death rates for COVID-19 in the initial outbreak in China indicate that elderly individuals (over 60 years of age) and individuals with pre-existing health conditions (cardiovascular disease, diabetes, chronic respiratory disease, hypertension or cancer) had higher death rates (7.3 to 10.5%) than younger, healthy people (1% death rate). Although deaths occurred in all age groups (except for children under 9 years of age) few children had serious symptoms. Deaths were thought to come about primarily due to uncontrolled activity of the immune system.

Men had a higher average death rate than women (2.8% vs. 1.7%). This may be due to gender differences in the ACE-2 receptor used by the virus to enter cells. The gene for the ACE-2 protein is on the X chromosome. So, women have two potential copies of the ACE-2 allele while men only have one. An even more compelling explanation for the elevated male mortality, though, may lie in the fact that men in China are much more likely to smoke than are women. China has the largest smoking population in the world (316 million smokers), and 51.1% of the Chinese male population smokes compared to just 2.7% of Chinese women.

 

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Signs of Spring 2: The Air Around Us!

 

The Apollo section of the Roaring Run Trail. Photo by W. Hamilton

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Almost every afternoon my friend Carl and I go for a walk usually on the Apollo section of the Roaring Run hiking trail. We’ve agreed on a few restrictions on our walks: the temperature can’t be below 24 degrees or above 90, it can’t be raining too hard (a light drizzle is OK, though, and snow is very acceptable), and there can’t be an on-going Code Orange (or higher) air quality alert.

The Pennsylvania Department of Environmental Protection (PA-DEPA) issues the color coded air quality alerts (Green (good), Yellow (moderate), Orange (unhealthy for select groups), Red (unhealthy), Maroon (very unhealthy) and Purple (hazardous)) based on their measured levels of ozone, particulates, sulfur dioxide, carbon monoxide and nitrogen dioxide in ground-level air. These pollutants come from a variety of sources including cars, power plants, factories, construction sites, incinerators and other types of fires. Ozone is especially formed in the summer when high temperatures and sunlight drive the conversion of some of these gaseous pollutants into ozone-rich soup of smog, but most of the other pollutants (especially the particulates) are present all year round.

When these continually generated pollutants become trapped in a ground level volume of air they can quickly build up to unhealthy levels. Stagnant winds and temperature inversions, a phenomenon where a layer of warm air forms over a lower layer of cold air and prevents its movement or mixing, can lead to the local accumulation of pollutants.  The river valleys of Western Pennsylvania are common places where temperature inversions can occur, and the frequent Orange alerts that are posted in our area throughout the year reflects this landscape influence on our air circulation.

We try to avoid exposure to these unhealthy air days, but, apparently, according to a paper recently published in the Quarterly Review of Biology (December, 2019) humans and their bipedal, pre-human ancestors have been walking about and living in various types of polluted air for many millions of years, and the evidence for this is written into our genes!

African savanna. Photo by Pixabay

Seven million years ago Africa became warmer and drier. One of the consequences of this climatological change is that the extensive forests of the African continent began to fragment and shrink leaving behind the great African grasslands called savannas. Primates, including some of our hominid ancestors, were very abundant in the African forests and were well adapted to arboreal life. The opening of the new, grassland habitats with their new resources and new sets of limiting factors, though, required a new set of anatomical features and specializations in order for a species to survive and succeed.  Some of these features were anatomical (upright body posture, bipedal locomotion, etc.) and are well represented in the fossils of Australopithecus, one of our first, savanna dwelling ancestors. Other adaptations were physiological and are only just being revealed by the exploration of our living DNA and the preserved DNA in fossilized bones.

For example, drying Africa was a dusty place especially near the expanding Sahara Desert. The new savanna was also filled with grass pollen and microscopic spores and particles from the breakdown of the carcasses and the fecal remains of the evolving, great herds of grazing mammals. The primate species that stayed in the forests (the future gorillas and chimpanzees) were shielded from these airborne pollutants, but the pre-human, primate species that moved out into the savannas breathed great quantities of these into their lungs.  One of the adaptations to this environmental stress was the development of a gene called the MARCO gene.

The MARCO gene enables macrophages throughout the body to grab on to bacteria or other irritant particles (like silica in the lungs) and remove them from contact with other, more sensitive cells. The version of MARCO seen in modern humans is quite different from the MARCO seen in present day apes. This modern human version has been dated to have finished forming about a half a million years ago and is found not only in Homo sapiens but also Homo neanderthalensis. It is hypothesized that the initial selection for this gene began many millions of years ago in the dusty savannas of Africa.

Public Domain

Homo erectus (the ancestor of both H. sapiens and H. neanderthalensis) domesticated fire possibly a million years ago. From that point on humans were extensively exposed to high levels of smoke and all of its associated toxins and irritants around campfires or in fire-heated dwellings.  There is a gene in many mammals that produces a protein found in the skin, intestines and lungs. This protein breaks down many types of food, water and air-borne toxins. The gene is called “AHR.”

AHR, though, is not meant to function continuously or at high levels. The action of its protein generates some very damaging molecular fragments from the toxin. In organisms occasionally exposed to a toxin, these damaging by-products are tolerated, but, in organism continuously exposed to some toxin, these breakdown products can do a great deal of harm. Modern humans, according to paper published a few years ago in Molecular Biology and Evolution (October, 2016) have a very weak version of the AHR protein, possibly because of their million years or so of continuous exposure to smoke.

Another gene that might be at least peripherally related to the developing adaptation of humans to savanna existence is the ApoE4 gene. This gene functions to help modulate the inflammatory responses to pathogenic and also parasitic infections. It is also affected by air pollutants. If an individual has a sequence of diseases and parasitic infections throughout their lives, the ApoE4 gene and its proteins apparently can help that individual focus the inflammatory components of their immune response to control or destroy the disease causing pathogen or parasite. If, however, an individual does not have a robust infection/parasite history, the ApoE4 gene can trigger unacceptable inflammation in many systems of the body including some sections of the brain. This inflammation is one of the causes of Alzheimer’s Disease, and the ApoE4 gene is a genetic marker for individual’s with high chance of developing early onset Alzheimer’s and also Alzheimer’s that is triggered by air pollution. (see Signs of Summer 13, August 17, 2017)

A recent paper in BMC Medicine (20 March, 2019) outlines the extensive mechanisms of influence of the ApoE4 proteins and their relationship to Alzheimer’s, cerebrovascular disease, vascular dementia, dementia with Lewy Bodies, and Multiple Sclerosis.  The functioning of this gene also illustrate a broader consideration of our evolutionary history and present day, post-industrial environment.

Humans have many genes designed to control and eliminate disease-causing agents from our bodies. The abundance of these genes reflects the impact that pathogens and parasites have had on human mortality and, therefore, human evolution throughout our long pre-industrial existence. With the development of sanitation and scientific medicine, death, particularly early, pre-reproductive death, due to infectious diseases has greatly declined. We still, though, have our full genetic arsenal that can trigger inflammation and immune system activity when stimulated by a wide range of environmental molecules that include many air pollutants. This has led to an increase in the chronic inflammation of many of the organs systems of our bodies. Alzheimer’s Disease, atherosclerosis (and its associated coronary and vascular diseases), chronic obstructive pulmonary disease, etc. are some of the great medical maladies besetting modern humans, and they may be the result of collateral damage from the inflammation that is triggered by our genetic adaptations to evolutionary and survival problems that we have so recently “solved” via our cultural and technological evolution.

 

 

 

 

 

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Signs of Spring 1: The Winter Cold (or Not)!

Photo by E.R.Vico, Flickr

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When we have a very cold winter, I often hear words of comfort from friends and acquaintances: “These cold temperatures, at least, will kill the ticks and fleas!” and “The cold, at least, will kill the mosquitoes,” and so on down a long list of forecasted doom for a variety of arthropod pests. There is a flip side to this cold winter optimism, though, and that is a prediction of an explosion of ticks, fleas, mosquitoes etc. when the winter is warm.

I wanted to explore these ideas since, as each of us must know by now, this year’s winter has been a very warm one. Globally, in fact, January 2020 was the warmest January in recorded history! Here in Western Pennsylvania the average temperature for our January 2020 was 37 degrees F. This is the warmest January that we have had since 2006 (38 degrees F), and it is nearly 10 degrees above our historical January average (28.5 degrees F). January 1880 was the warmest January ever in our region (average monthly temperature that year was 44.4 degrees F). There are only a handful of Western Pennsylvania Januaries, though, that have been warmer than the one we just experienced!

So, are over-wintering arthropods, especially insects and arachnids, affected by warm (or very cold) winter temperatures? The answer is “yes” and “no.”

There are a number of strategies that insects and arachnids use to survive the winter. Some involve avoiding the cold either by finding natural hibernating spots (like insulated spaces in the soil or protected cavities under the loose bark of trees or even inside the dead bodies of the previous year’s adult life stages) or by finding similar spots within human houses and other buildings. Some of these human habitat hibernators, though, actually can be negatively affected by the consistently warm temperatures of their refuges. Hibernators are well adapted to lowering their basal metabolic rates with decreasing temperatures but may, when the house or building in which they are hibernating is kept uniformly warm, experience elevated basal metabolic rates and as a consequence use their body fat reserves too rapidly and starve before Spring arrives.

Eastern tent caterpillar tent. Photo by Esc861, Wikimedia Commons

Eastern tent caterpillars overwinter as first instar caterpillars still encased in their eggs, and common bagworms overwinter as unhatched eggs These caterpillars and eggs are packed up inside well insulated egg sacs that are attached to tree bark and other types of plant stems. For bagworms, larger egg sacs are better insulated and provide better protection from the cold, and for both species specific location of the eggs sac placement can affect survival. Very cold winters can kill these overwintering organisms, but for eastern tent caterpillars

Adult bagworm. K.Schultz, Wikimedia Commons

these have to be temperatures lower that -31 degrees F (University of Kentucky Agricultural Bulletin). For bagworms in large eggs sacs, 50% lethality is seen at temperatures just under 0 degrees F (Canadian Entomologist February 2013).  Temperatures warmer than these extreme cold readings allow for the significant survival rates (typically 80%) of the overwintering egg/caterpillars. The latitude line of winter cold lethality changes with changing seasonal temperatures. As climate warms, this line is pushed ever further to the north, exposing higher latitude forests to these defoliating insects. And, if climate cools, this infestation line drops to the south.

 

Insects can also alter their body fluids with chemicals that act natural anti-freeze. These “supercooled” individuals ride out the cold temperatures in an apparently frozen, inactive state, but readily thaw out and regain full function when the temperatures moderate. Other insects synthesize special proteins that resist freezing. These proteins are concentrated in certain regions of the insect’s body where they protect vital organs and allow less vulnerable parts of the organism to freeze.

Most insects and arachnids require temperatures of at least 50 degrees F for full activity, but all of the behavioral and physiological tools they can employ allow many of them to wait for the 50 degree days to arrive with very little damage to their tissues or organs.

Most of “endemic” species of arthropods (that is, those species that are native to this area and have evolved to survive in the changeable seasonal climates of our region) very easily survive both colder than average and also warmer than average winters. They also survive the occasional cold snaps of spring. The timing of the early spring emerging endemic insects, though, may occur either earlier than normal (if the winter/spring has been warmer than average) or later than normal (if the winter/spring has been colder than average). These insects, then, may emerge ahead of or lag behind their targeted spring plants. Endemic, summer-active insects, though, don’t seem to be greatly affected in any way by prolonged winter cold periods or spring freezes or rising winter temperatures and early spring thaws (data from the Ohio Agriculture Research and Development Center).

Photo by H. Russell, Wikimedia Commons

Non-endemic arthropods may be affected by our roller coaster Spring weather patterns especially if those exotic, invasive species have come from areas where the evolutionary selection for suitable weather survival mechanisms has not occurred. Two invasive species that may be at least somewhat inhibited by cold weather and stimulated by warmer weather are the emerald ash borer and the hemlock woolly adelgid. Cold northern winters may also push the invasion line of the southern pine beetle (an endemic species of the southern United States that has spread into the north) further back to the south, and, as we discussed above for the common bagworms and eastern tent caterpillars, warmer temperatures may allow these pests to push into increasingly northern regions .

Life stages of the dog flea. Welcome Images, Wikimedia Commons

So what about fleas? Cold temperatures (defined as temperature of 40 degrees or less) will kill adult fleas, but the immature life stages of the fleas (larvae, nymphs, or eggs) are extremely tolerant of very cold temperatures. So the adult fleas outside will die in the winter unless the winter is so warm that 40 degree F low temperatures are not reached, but even if these adults life stages are killed there will be significant numbers of the cold resistant immature life stages to repopulate the ecosystem and infest our pets once warm weather has returned. A cold spring might delay the flea explosion, but it will eventually occur! An interesting but potentially unpleasant side note to this flea discussion concerns fleas that are living inside of a house. Cold winter temperatures never do kill off the indoor dwelling adults (not even I would set my house thermostat down to 40 degrees!), and these fleas may stay active and continue to infest the resident dog or cat all winter long.

Mosquitoes?   Same idea. Endemic mosquito species in their overwintering life stages don’t seem to be affected by very cold winter temperatures. For some species of mosquitoes the overwintering life stage is a cold resistant egg, while for other species it is a larva that lasts through the winter. There are even some mosquitoes in which mated adult females are the overwintering life stage. These adult females, when they emerge in the spring, are ready right away for a blood meal so that they can finish making their eggs. Again, cold spring temperatures may delay their emergence, and warm spring temperatures may hasten their emergence, but neither seems to significantly affect their numbers.

Aedes aegypti Photo by J. Gathany CDC Wikimedia Commons

Non-endemic, especially southern mosquitoes, though, like Aedes aegypti (the mosquito that carries Denge fever, yellow fever and the Zika virus) are killed by cold winter temperatures. These mosquitoes are intruding into our region during the summer but are not yet setting up locally persisting, reproducing populations. Rising winter temperatures, though, may soon allow these dangerous mosquitoes and several other warm-weather species to become permanently established here in Western Pennsylvania.

Photo by D. Sillman

And, what about black-legged ticks? These are the arthropods that can transmit the bacterium that causes Lyme Disease, and these ticks for a variety of reasons (see June 2, 2016, Signs of Summer 2 for a discussion) have in recent years greatly increased in numbers throughout the eastern United States (including Western Pennsylvania). A study published in 2012 in the Journal of Medical Entomology clearly showed that in spite of “common knowledge” to the contrary, cold winters (and they used Upstate New York as their cold winter site!) do not reduce the numbers of overwintering black-legged ticks. The ticks just have too many adaptations for cold tolerance and too many protected microhabitats available for even the most brutal of winter temperatures to have any effect on them at all. Warmer winter temperatures, though, may allow an earlier Spring emergence and more rapid advancement of the ticks through their reproductive cycles which could lead to larger and larger populations of this species.

Another tick of great interest that may be expanding its range northward because of warmer winter temperatures is the Lone Star tick (Amblyomma americanum )(also called the “turkey tick”).  This tick is a vector for a variety of  illnesses including ehrlichiosis, tularemia and the southern tick associated rash illness (STARI). They can also transmit the heartland virus. The Lone Star tick also can cause a human host to become severely allergic to dietary meat by the bite injection of an immunologically active, salivary carbohydrate called galactose-alpha-1,3-galactose. This oligosaccharide, which is present in all mammalian meats except those found in primates, stimulates the human immune system to make IgE antibodies  which mediate a delayed, but extremely severe, anaphylactic response when the sensitized host eats any mammalian meat.

So if our winters are getting warmer many trees pests may invade into more and more northern forests. Most endemic insect species won’t be greatly affected, but early spring emerging species may get out of synch with their obligatory spring plants. Disease carrying “southern” mosquitoes and ticks may become established in more northern regions, and endemic fleas and ticks may get active earlier in the season and reproduce more rapidly.

Do you miss the good old winters? Let’s all remember January 1977 when our average monthly temperature was 12 degrees F! Take that you bagworms and tent caterpillars!

 

 

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Signs of Winter 11: Natural History of a Northern Red Oak

Photo by D. Sillman

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I have seen  many northern red oaks (Quercus rubra) along the hiking trails of Western Pennsylvania. Their very distinctive, vertically striped bark helps to them to stand out even in dense mixed growths with many other tree species. The picture to the left shows a large northern red oak along the Baker Trail just west of Cochran’s Mills.  Many of the forests in which these red oaks are found are secondary or even tertiary growth forests. The pre-settlement, primary structures of these forests were quite varied. Some were dominated by white oak, American chestnut, and yellow poplar, others by white pine, and even others by eastern hemlock and American beech. Almost all of these starting forests, though, after they were cut, ended up with increasing percentages of northern red oaks in their developing forest ecosystems.

The northern red oak is the embodiment of a generalist. It grows on a great variety of soils and is found in almost any topographic orientation (Sander 1990). It has a very broad geographic range over the eastern half of the United States that stretches north into southern Canada and into Nova Scotia (it is the most northerly distributed oak) and south to just above the Gulf coast (Little 1979). It grows best, though, in moist soils with deep “A” (upper, organic-rich) soil horizons, and on lower, concave slopes with either northerly or easterly exposures (Sander 1990).

Northern red oaks can be found occasionally in pure stands but most frequently they grow in mixed forests often with white pine, red maple, and white and black oaks. It is also associated with species like white ash, green ash, big-toothed aspen, American elm, slippery elm, the hickories, scarlet oak, and more (Braun 1950, Eyre 1980).  Its wide range of site tolerances and its tenacious survival in forests undergoing stress make it an increasingly common component of our eastern forests.

Photo by D. Sillman

Just off of the upper section of the Ravine Trail on the Penn State New Kensington Nature Trail is a large (50 foot tall, 18 inch diameter) northern red oak five yards down the hillside, growing at a fifteen degree angle up into an open section of the canopy. The crown of the oak fills a gap between the yellow poplar and black cherry trees that are quite abundant on the upper section of the slope and the American beech and red maple that grow on the bottom of the hill.

Around the base of the red oak is a dense thicket of raspberry and spice bush. There is also abundant wild grape growing on the ash trees, but none on this particular oak.

So, why is this northern red oak here?

As I have said for other trees, northern red oaks have to come from northern red oaks. So, this tree, which is about 80 years old, had to arise initially from a parental tree that was, at least somewhat, nearby. The seed of red oaks are acorns, and acorns are common foods for many large birds and many large and small mammals. Wild turkey, crows, blue jays, squirrels, chipmunks, mice, voles, and white-tailed deer all eat acorns. In a good reproduction year (lot’s of acorns!), eighty percent of a red oak’s acorns are consumed by these vertebrate consumers and also by a host of invertebrates. In a bad reproductive year, though, one hundred percent of the red oak’s acorns may be consumed (Marquis et al. 1976, Sander 1979). But, there is always a chance, especially in a “good’ reproductive year when there is an overwhelming abundance of acorns, that some of the gathered acorns may be dropped and forgotten. Most red oak acorns fall and remain near the parental tree (Sander 1990) but dispersal of acorns by crows and jays can involve surprisingly large distances.

Red oak bark. Photo by D. Sillman

For example, my house sits on two acres in southern Armstrong County. The trees growing on my property are a mix of red maple, silver maple, red pine, eastern hemlock, blue spruce, Norway spruce, slippery elm, white ash, American chestnut, apple, pear, and black locust. When we moved to this house 30 years ago there were no oaks of any kind within a three quarter of a mile radius of our house. Eighteen years ago, though, I found seven oak seedlings (three white, two black, and two northern red) growing in the partial shade under two of my spruce trees. When those spruce trees (and six more of their spruce cohort)  were blown down in a microburst a few years later, these skinny oak seedlings and a dozen or so other oaks whose presence I had not detected, started to rapidly grow! These oaks are now over 25 feet tall and are spreading their branches into the spaces left empty by the departed spruces. I assume that the acorns from which these oaks arose were deposited in my yard by some of the very abundant crows or blue jays that occasionally occupy parts of my yard and field. These trees, then, had great mutualistic assistance that enabled them to “fly” substantial distances from their parental sources.

So, our northern red oak here on the Nature Trail could have come from a parental tree a mile or more away. This parental tree, like all northern red oaks, had both male and female flowers and flowered in the spring (Sander 1990). The pollen was dispersed on the wind and a very small percentage of it was deposited in a female flower. The fertilized ova in the female flowers formed acorns (in clusters of 2 to 5) which then took two years to mature. The brown, mature acorns fell from the parental tree in September or October (Schopmeyer 1974).

Northern red oaks begin to produce acorns when they are twenty-five years old but do not produce abundant acorns until they closer to fifty years old. “Good” acorn crop years occur every two to five years, but some individual trees never make very many acorns at all (Schopmeyer 1974).

So, the parental tree of our northern red oak may have flowered in late May, eighty-two years ago and set the acorn that would become our tree. The mature acorn, then, two years later, either fell to the ground under the parental tree to wait for spring to germinate, or it was carried off by a squirrel or by a crow or blue jay, dropped, and then forgotten. The overwintering acorn was probably in contact with moist, mineral soil, and was also probably covered by a layer of fallen leaves. Contact with soil and protected, moist conditions are critical for acorn germination (Sander 1979). In the spring the acorn sent a long tap root down into the damp soil and slowly began to grow its root system (Sander 1990). It’s above ground stem and leaves grew even more slowly in cool, shade of the forest.

Overall, northern red oak seedlings grow very slowly and are extremely sensitive to drought (Seidel 1972). Their need for sunlight to drive their photosynthetic energy metabolism must be balanced against the potentially fatal, drying impact the sunlight has on the moist soil. The red oak, then, exists on an ecological razor’s edge, and this survival edge changes through the years in which the seedling grows and matures.  Shady, very moist conditions are required for germination and initial seedling survival, but as the root system develops (and there are more roots to an oak seedling than above ground stem!) the moisture stress eases and increased levels of sunlight are not only tolerated but are required to maintain existence and fuel growth. Larger seedlings will die of there is not sufficient sunlight to drive their photosynthetic metabolisms (Sander 1990).

Northern red oak seedlings, then, have very narrow, very specialized niche requirements, and the character of these requirements change through development. It is not surprising, then, that these seedlings have a very high mortality rate. Low moisture, too much sunlight, too little sunlight, animal activity (including deer browsing), fire, or insect damage can destroy the stems and leaves of these young trees. Destruction of the above ground portions of these trees, though, often leaves the below ground roots intact. New sprouts are then able to grow from these roots and are able to re-establish the northern red oak seedlings.

This cycle of stem death and root sprouting can occur many times in the life of an individual red oak. Many stems, for example, have root systems that are ten to fifteen years older than they are (Sander and Clark 1971)! This ability to vigorously and repeatedly re-sprout is an extremely important aspect in the ecology and survival of this tree species. Once a red oak acorn germinates (and less than one percent of acorns have an opportunity to do this!) and then has several years in which it can grow its root system (and very, very few seedling survive the first year or two of life), it then possess a remarkable degree of tenacity and persistence which, in spite of its slow rate of growth and in spite of all of the destructive things that can and probably will negatively impact upon it, enables it to survive and even come to dominate many potential types of forest ecosystems.

Photo by Kshera502, Wikimedia Commons

Red oaks can live up to 400 years and may reach impressive girths and heights. A famous, old red oak grows in the backyard of a house on Shelby Street in Frankfort, Kentucky. This tree is called the Shera-Blair Red Oak, and it has a circumference at breast height of 21 ft and a trunk that rises more than 40 feet before it branches. It has an estimated height of 130 feet.

Ninety-five percent of existing northern red oaks are sprouts (Sander 1990) These trees, especially in ecosystems under stress (like from fire, logging, deer browsing, disease, and insect defoliation (as from gypsy moths)), expand their influence with each passing stress event. Other, less well adapted and less vigorously sprouting tree species decline with each passing trauma while the red oaks persist and actually increase their numerical dominance. Red oaks are adapted to pass through these “ecological stress filters” much more readily than most of the other tree species in their forest community. So, over time, especially if some stressful agent is at work on the forests, the northern red oak will out compete and out survive most of their potential canopy competitors. Forked stems which are very common in northern red oaks (as seen in the picture below from a section of the Laurel Highlands Trail near the Route 30 crossing) are indicative of sprouts (Sander 1990).

Photo by D. Sillman

Back to our northern red oak on the ravine slope of the Nature Trail: the above ground tree is eighty years old, but the roots could be as closer to one hundred. The parental tree may have flowered a century ago and its germinating acorn and its seedling and sapling may have undergone extensive stress and destruction until, phoenix-like, this tall, straight stem finally persisted and “won” this section of the canopy.

In the fall, there are abundant acorns on the trail under this tree (and by spring almost all of them are gone, thanks, I am sure, to large, local populations of wild turkey and white-tailed deer!). There are many red oak seedlings growing under the cover of the raspberry and spice bush. There are fewer red oak saplings growing up above the shrub layer, but still enough to be easily noticed. Our tree, then, has survived and established itself as a major component of the evolving forest along our Nature Trail. I expect that, barring catastrophes, or maybe because of them, the offspring of our tree will increase in number and size over the coming decades and come to dominate this forest. We’ll check back in a hundred years or so to see!

References for Northern Red Oak:

Braun, E. Lucy. 1950. Deciduous forests of eastern North America. Blakiston, Philadelphia, PA. 596 p.

Eyre, F. H., ed. 1980. Forest cover types of the United States and Canada. Society of American Foresters, Washington, D.C.

Little, Elbert L., Jr. 1979. Checklist of United States trees (native and naturalized). U.S. Department of Agriculture, Agriculture Handbook 541. Washington, DC. 375 pp

Marquis, D. A., P. L. Eckert, and B. A. Roach. 1976. Acorn weevils, rodents, and deer all contribute to oak regeneration difficulties in Pennsylvania. USDA Forest

Service, Research Paper NE-356. Northeastern Forest Experiment Station, Broomall, PA 5 p.

Sander, Ivan L. 1979. Regenerating oaks with the shelterwood system. In Proceedings, Regenerating Oaks in Upland Hardwood Forests. John S. Wright Forestry Conference. p. 54-60. Purdue University, West Lafayette, IN.

Sander, Ivan. 1990. Quercus rubra L. Northern Red Oak.  In, Burns, R. M. and B. H. Honkala (tech coord) “Silvics of North America: Volume 2, Hardwoods.” U.S. Department of Agriculture, Agriculture Handbook 654. Washington, D. C.877 p.

Sander, Ivan L., and F. Bryan Clark. 1971. Reproduction of upland hardwood forests in the Central States. U . S. Department of Agriculture, Agriculture Handbook 405.Washington, DC. 25 p.

Schopmeyer, C. S., tech. coord. 1974. Seeds of woody plants in the United States. U.S. Department of Agriculture, Agriculture Handbook 450. Washington, DC. 883 p.

Seidel, Kenneth W. 1972. Drought resistance and internal water balance of oak seedlings. Forest Science 18(l):34-4

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Signs of Winter 10: The Biodiversity Hypothesis and the Wonder of Soil!

Photo by D. Sillman

(Click here to listen to an audio version of this blog!)

When I was in graduate school at SUNY-ESF there was a large, on-going project involving the use of sewage sludge as a forest soil amendment.  One ESF professor was particularly excited to be working with ripe, fresh, sewage sludge. As he explained to us on the days in the field when we were hauling and spreading the sludge on our test plots, people who work with the sewage sludge in water treatment plants almost never got sick! The constant exposure to the aerosol of bacteria and viruses emanating from the sewage, he hypothesized, supercharged their immune systems and kept them from catching any of the more common, or mundane illness circulating around them!

As far as I know, the data on the workers “who never got sick” was anecdotal. I have never seen any statistics on it. The manic focus and evangelical fervor of this professor, though, made me avoid him for the four years I was at ESF. One of the other professors on the project with whom I did work and did get close to later told me that this first professor (and I am being very careful not to use any names here!) was trying to design little boxes that released aerosol sprays of sewage tinted air certain that everyone would want them for their homes. He was sure that no one would ever get sick again! He was also confident that he would receive a Nobel Prize in medicine for this work!

The boxes were never marketed. The Nobel Prizes (so far) have all gone to others. But, recent research indicates that the fundamental idea here may have some merit!

Public Domain

Sanitation is one of the great health achievements of human culture. Modern industrialized societies, though, have taken the idea of sanitation to extremes especially when it comes to infants and children. If exposure to potential pathogens may cause disease, then, logically, you should do anything you can to eliminate the chance of any exposure or contact with any microbe at all. Extremely clean nurseries and homes (and all of the cleaning and sanitizing products that have made this possible) were the goals of the modern, industrialized household. Isolating children from portions of the human population that might carry potential pathogens and restricting the exposure of children to dirt and contaminants of the surrounding world were considered to be obligations of the modern parent.

These acts, though, had profound impacts on the immune systems of these “sanitized” children. The human immune system has evolved to “expect” a series of pathogen exposures especially in early life. These pathogens allow the immune system to learn to synthesize the correct types of proteins and immune cells to form an efficient, disease fighting system for life. Research indicates that when these early life microbial exposures do not occur, the immune system develops some odd, and potentially destructive pathways that include the generation of allergies, eczema, asthma and, possibly a number of “autoimmune” disease syndromes. This is the essence of the “hygiene hypothesis” that was first articulated back in the 1980’s and 1990’s. The stunting of the immune system’s evolutionarily derived education/maturation period may at least partially explain the epidemic of allergy and asthma cases that are seen in our industrialized societies (see “Our WEIRD World” blog, August 17, 2017).

There is some very interesting work coming out of the University of Helsinki that expands the hygiene hypothesis ideas past simple pathogen exposures to include an incredibly broad range of soil dwelling bacteria. This array of environmental microbial exposure modifies an individual’s cutaneous and intestinal microbiomes and steers their immune systems and other physiological processes of the body into a healthy homeostasis. This new model of immune system development is called the “biodiversity hypothesis” and its functioning depends on the biological diversity of the ecosystems in which we live!

Karelia Russia (on Russian-Finish border). Photo by Ninara, Wikimedia Commons

One of these studies, published in the journal Clinical and Experimental Allergy in 2017, looked at the large, relatively homogeneous population of people living on the border between Finland and Russia who were separated by treaty agreements during World War II. The population on the Finish side of the border became quite affluent and urbanized during the second half of the 20th Century while the population on the Russian side maintained their traditional, predominantly rural existence. Researchers found that the children on the Finish side of the border had a significantly higher incidence of allergies and asthma than the Russian side children. The Russian side children, who lived in closer contact with forests and fields than the Finish children, also had more bacteria and more kinds of bacteria in their skin microbiomes. These resident bacteria included a number of species that are associated with plants. These “country dwellers” also had higher levels of blood leukocytes and higher potential production rates of anti-inflammatory cytokines.

To explore the connections of these findings, experiments involving asthma-model mice were then conducted and published in the Journal of Allergy and Clinical Immunity in March 2019. These mice (who exhibit the same Type 2 T Cell immune response that triggers human asthma) were raised in cages to which soil had been added to the bedding. These cages were also housed in facilities that contained other types of animals. Compared to controls, these soil-animal-contact mice were less susceptible to asthma triggers and had altered gut microflora compositions that were consistent asthma/inflammation reduction. They also had elevated levels of immune system controlling, anti-inflammatory proteins.

Lab mouse. Photo by Rick Eh? Flickr

A second set of experiments conducted by researchers at Flinders University in Australia and published recently in the journal Science of the Total Environment (20 January, 2020) put the soil outside the cages of the asthma-model mice but added ventilation systems that  blew air across the soil and into the cages. This experiment replicated the experience of being outside in a soil surrounded environment. These mice, too, had characteristic asthma-resistant microbiome changes and a reduction in asthma/inflammation reactions.

Numerous studies have demonstrated that contact with natural ecosystems is beneficial to human physical and mental health. In a recent report published in Scientific Reports (13 June, 2019) a minimum exposure to outdoor environments of just two hours per week was shown to have significant impacts on and individual’s health and sense of well being. Brain pathways triggered by adding the smells of natural ecosystems to virtual reality presentations indicate profound, innate neural responses to interactions with nature (see Scientific Reports (12 July, 2019).

Many of these studies discuss the positive impacts of exercise, fresh air, and social interactions as active components of an outdoor experience, but almost all of them indicate that none of these very obvious, positive aspects of an outdoor experience explains the full range of health benefits that are observed. Possibly, the biodiversity hypothesis and the transformation of one’s microbiome via exposure to the full range of microbial diversity in outdoor ecosystems is one more piece in our understanding of our need physiological for nature.

 

 

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Signs of Winter 9: New Ideas on the Evolution of Land Plants

Photo by NASA, Public Domain

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The Earth is about 4.5 billion years old. Life began on Earth (best guess) about 3.5 billion years ago. The first organisms were bacteria: very simple entities on the eventual, massive scale of life, but incredibly complex entities on the immediate scale of physical and chemical systems of ancient Earth!

It is hypothesized that these bacteria lived by breaking down the reduced organic molecules that had accumulated via relatively slow, chemical processes over the Earth’s first billion years of existence. Living organisms, though, use energy rapidly, and the rapid breakdown of the slowly synthesizing food molecules began to exhaust the food supply and triggered the Earth’s first Mass Extinction.

Photosynthesis is a biological process that uses some wavelengths of sunlight to fix carbon dioxide into sugar molecules. It is the energy foundation for almost all present day ecosystems! The initial evolution of photosynthesis saved life from Earth’s first Mass Extinction by providing a reliable and robust source of food energy, but it was also the direct cause of the second Mass Extinction event some 500 million years later.

Stromatolites (in Hoyt Limestone, Saratoga Springs, NY). Photo by Rygel, Wikimedia Commons

The original photosynthesizing organisms were bacteria that lived in (or more precisely “on”) Earth’s ancient oceans . Fossils of these ancient “blue-green algae” (more precisely called “cyanobacteria”) can be found in layered rocks called stromatolites. Some of these stromatolites have been dated to be over 3 billion years old. The great, floating masses of cyanobacteria captured sunlight, fixed carbon dioxide and removed hydrogen  atoms from water to make sugars. They also released a waste product (oxygen) from the cleaved water molecules. Molecular oxygen, quite possibly, had never existed on Earth before this. The buildup of oxygen played havoc with the gas molecules of the volcanically derived, reducing atmosphere of the Earth and transformed it into a gaseous system that began to resemble the atmosphere we know today.

In this Second Mass Extinction any life forms on ancient Earth that were intolerant of oxygen (probably most of them) were killed off or forced to retreat into microhabitats from which the oxygen was excluded. Other organisms, though, evolved metabolic pathways by which the oxygen molecules were rendered harmless. These pathways, coincidently, conveyed great energy generating advantages to some of these species. The species that could tolerate and then utilize the photosynthetically generated oxygen in their energy generating metabolisms (the aerobic species) thrived in this Earth 2.0 (or is it 3.0?) and evolved and diversified into the large, complex life forms we see around us today!

The evolution of photosynthesizing species established a new balance between energy fixation and consumption on Earth! Life, though, was still confined to the oceans. Many problems had to be solved before living organisms could live outside of the sea, and those solutions did not come about for another 2 billion years (just 475 million years ago)!

Green algae on beach. Photo by D. Ramirez, Wikimedia Commons

Green algae are the logical evolutionary forerunners of land plants. They are, though, an extremely diverse group of organisms, and the determination of which type of green algae made the transition from aquatic to terrestrial habitats has been a topic of great speculation and contention.

Historically, the charophytic green algae have been put forward as the most likely evolutionary starting point for land plants. Their physical appearance (they are multicellular and have complex, very “plant-like” structures and shapes), their cellular features and physiologies (they have many of the same enzymes and pigments as green plants) all seem to make their connection to land plants quite logical. As one researcher put it, “they look like underwater plants!”  However, using increasingly robust genome sequencing techniques, researchers noted that the genes of charophytes do not match up very well with the genomes of early plant species. Instead, the genes of another, much simpler green algae group, the Zygnematophyceae, are the closest match to the early plants.

Spirogyra (a Zygnematophyceae green algae). Photo by Bogan, Wikimedia Commons

Ecologically, there are several species of Zygnematophyceae that are able to live outside of purely aquatic environments. These algae grow on rocks and other hard substrates alongside ponds or streams or even in wet forests. These algae, then, have some land-dwelling capabilities built into their ecological skill sets, and the gene sequences of two of these species are very similar to the genes of early green plant species. Further, several of the genes present in these algae (and also found in land plants) are not found in any other algae group!

One of these unique gene sets coded for features that allow the algae and plants to survive a variety of stresses including water deprivation. Modern plants utilize these genes to make drought resistant spores and seeds. These genes also very precisely match up with a number of genes found in soil dwelling bacteria, and it is hypothesized and discussed in a recent paper in the journal Cell (November 14, 2019) that these bacterial genes were transferred en masse from the ancient bacteria to the evolving algal cells that then became land plants.

This is an example of “horizontal” gene flow, a process that is well known in purely bacterial communities. The bacterium to bacterium transfer of genes that increase the pathogenicity of a formerly benign bacterial species or the transfer of genes that code for antibiotic resistance from one species to another are well documented. In fact, they go on in your colon all the time! The transfer of genes from bacteria to the much more complex cells of plants and animals, though, is a process that has been hypothesized but not extensively documented.

Moss (a “primitive” plant). Photo by Y. Semenenko, Wikimedia Commons

A couple of weeks ago we talked about the Tree of Life as a model of evolution (see Signs of Winter 6, January 23, 2020). In the Tree of Life genetic diversity is generated exclusively by mutations within the genomes of each species, and out of these “nodal” increases in genetic diversity new species may arise via “vertical” evolution. In the case of the evolution of land plants, though, and possibly in the evolution of many other groups or species, wholesale additions of genes from other types of living organisms (completely different branches on our Tree) may have occurred. These genes can initiate massive changes in the receiving organisms, and these changes may convey significant ecological or evolutionary advantages to the receiving species. It is as if the branches on the Tree of Life were bifurcating and then fusing with each other sharing genetic information that was thought to be isolated and unique.  The Tree, apparently, is much more fluid and dynamic than we ever imagined!

What are the implications of horizontal gene flow and horizontal evolution? First and foremost it provides a mechanism for very rapid evolutionary transformation! A species can pick up entire genetic sequences that enable them immediately to make new structures or carry out new physiological processes. This type of evolution does not have to inch forward one point mutation at a time!

And, secondly, the reality of horizontal gene flow contains a cautionary message: when we add new genes to a species and then release that species into a community of other types of organisms, there is the possibility (whose probability is not yet known) that those genes may horizontally flow into other species. The phenomenon of herbicide resistant weeds forming near fields with herbicide resistant GMO crops is a possible example (and a very dangerous one!) of this possible horizontal flow!

 

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Signs of Winter 8: The Great Backyard Bird Count (2020)

Photo by D. Sillman

(Click here to listen to an audio version of this blog!)

Starting next Friday (February 14th) and running until the next Monday (February 17) the Cornell Laboratory of Ornithology, the National Audubon Society and  Birds Studies Canada are sponsoring their annual “citizen’s science” project called “The Great Backyard Bird Count” (GBBC). This word-wide count of birds began in 1998 and has grown in scope and in participation with each passing year. Participants are asked to spend fifteen minutes either stationary at some observation point or walking through a habitat counting and identifying the birds they see. On-line checklists developed by eBird facilitate the reporting of these observations, and the compilation of the data from the observers seems to be nearly instantaneous!

If you are interested in participating in the count click here for more information!

Some highlights of the 2019 bird count include the number of checklists (209,854) and the total number of species observed (6848)! Also 32,421,863 individual birds were counted, and 224,781 people participated!

Photo by D. Sillman

There was a distinct North America bias to the 2019 count (as has been the case since the count began) because almost two thirds of the checklists come from the United States. The ten most frequently mentioned species on the lists were all very common North American species (led by the northern cardinal, the dark eyed junco, the mourning dove and the downy woodpecker), and all of the top ten most numerous birds in the count were also North American species found in large flocks (the count of over 4 million red-winged blackbirds topped this list with just under 2.5 million snow geese in second place!). Pennsylvania, by the way, was fifth last year in total number of checklists per state submitted to the count and looking down the list of names of participants who submitted check lists from Pennsylvania counties I found a number of regular readers of this blog! In 2017 Pennsylvania was number two on the checklist list well behind the much more populous California! Last year we were number four! We need to get more of us out there this year (California may be out of reach, but we can’t let New York, Texas and now Florida edge us out again!).

Evening grosbeak. Photo by A. Elliot, Flickr

Some highlights from the North American data in the 2019 count:

  1. In the eastern United States a number of evening grosbeaks were observed by GBBC participants. These birds have been absent from this area’s GBBC data sheets for the past several decades! Why they were gone and why they came back is a mystery!
  2. A large number of “northern finches” were observed in the United States. These finches included red crossbills, common redpolls and pine grosbeaks. Another poor seed production year in the northern coniferous forests is thought to be the force driving these species south. The numbers of these finches observed in Canada during the GBBC were, logically, correspondingly low
  3. Bohemian waxwings were widely seen across the northern portions of the United States. Were these flocks fleeing bad weather or looking for food?
  4. Two years ago (2018) there were many sightings of snowy owls throughout the northern United States, but in 2019 there were very few. Many snowy owls were observed in Quebec and Ontario in 2019, however. In 2018 their presence so far south was explained by a lack of food in their Canadian habitats possibly due to their own rapidly increasing population. An alternative explanation was the severe winter weather in Canada that might have interfered with their hunting. Possibly their prey populations (especially lemmings!) have recovered from last year’s low levels, or perhaps this year’s snow cover in Canada was light enough to not interfere with hunting.
  5. Killdeer. Photo by Pixabay

    There were very few early spring migratory bird species in the northern United States in February 2019. No killdeer or American woodcock were observed and very few common grackles or red-winged blackbirds. Interestingly, the red-winged blackbirds must have still been massed together in their huge overwintering flocks  throughout the south, and  these flocks must have been observe by GBBC participants. This explains how this species rose to the top of the “most numerous” species list this year!

    Yellow grosbeak. Photo by Pixabay

    6. A white-throated thrush was seen in Arizona, and a yellow grosbeak was seen in Texas. Observing these two Mexican and Central American species so far north was reflective of a broader trend of the northward movement up through Mexico of many southern species (including the green jay, the clay-colored thrush and the ringed kingfisher). Climate change is thought to be the driving force for these observed changes. Concerns have been raised about the quality of habitats these northwardly transitioning birds are entering.

  6. In Newfoundland and Labrador GBBC observers saw a number of over-wintering sparrows including a single Savannah sparrow and a number of white-throated sparrows and fox sparrows). Again, is this just a anomaly that will correct itself next year or the start of a possible climate shift change?
  7. And, in Saskatchewan, an American white pelican and a double crested cormorant spent the winter by the river near Gardiner Dam. The river didn’t ice over this year and, thus, allowed these fishing birds access to food with little competition. Is this another oddity of this particular year or the start of a trend driven by climate change?

Explore the data and read more about the 2019 GBBC at the GBBC website!

Snowy owl. Photo by P. K. Burian. Wikimedia Commons

I wish that I had seen a snowy owl or a pelican (not to mention an evening grosbeak!) when I did my GBBC observations! The species that I counted for my two 2019 lists, though, were as common as they could be. All of my 13 species were included on the overall study’s “most frequently listed” species table. My birding experience doesn’t range into wild, exotic discoveries. My birds are cardinals, house sparrows, dark-eyed juncos, white-throated sparrows, house finches, blue jays, tufted titmice, black-capped chickadees, white-breasted nuthatches and American crows. These are the same birds that I have written about in this blog so many times! I saw and counted them from the comfort of the front window from my dining room and from my sun porch (Hey, it was COLD outside that day!). I was happy to add my rather plain set of birds to the accumulating mass of observations from all around the world! I can’t wait for next weekend to do it again!

 

 

 

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