Signs of Spring 10: Watching Some Birds

Photo by D. Sillman

A couple of weeks ago I was sitting in my car up in the parking lot of the Environmental Learning Center at Harrison Hills Park just next to the purple martin houses. I had just walked my bluebird circuit to check our nesting boxes and was waiting for Deborah to return from an early season wildflower walk. It was a cool, cloudy day, and I had to keep the car windows rolled down to prevent fogging them up with my breath. I spent my car time looking at birds.

The purple martin houses were recently uncovered, but the martins had not yet returned from their over-wintering ranges (they are back now, though!). The large, communal houses remind me of my old neighborhood in Houston. It seemed like every other house on my street had one of these purple martin apartment complexes prominently displayed on a tall pole. I can’t remember how many of them actually had birds in them, though.

A northern flicker landed in a circle of low grass and started very purposefully pecking the ground. I assumed he was eating ants (a flicker’s favorite food!) and I glanced at my watch to make a note of how long he would stay in that spot anting. He hardly moved a half a meter in the hour and a half! His hunting style was as stationary as could be! Find a place with ants, stay put and eat the ants! Sometimes life is a simple equation!

Photo by D. Sillman

About twenty meters from the flicker five robins were also looking for food. I assumed that they were looking for earthworms that might be lingering on the surface of the wet soil. The robins moved in a beautifully choreographed dance across the grassy field: each bird stayed about five meters away from their closest neighbors. When one bird moved the others reacted, and the small flock methodically worked their way across field. Their movements were sudden and saltatory: five or six quick steps, a head turn to focus one of their eyes on the ground (they usually used their right eye) and very occasionally a peck and grab, and even more occasionally a head shake and a swallow. Once or twice a new robin landed among the hunting cohort. This threw all of the established birds into a cackling furor. The robins flapped their wings and lifted up a foot or so about the ground, and then re-settled into their familiar spacing with their additional flock member and continued to work the field.

Bluebirds (early arriving males) were also out in the field. They flew from clump of tall grass to clump of tall grass grabbing onto the upper portion of the grass stems to survey the section of the field in front of them. They seemed to avoid the part of the field being worked by the robins and flew many tens of meters at a time from grass clump to grass clump. I could see the bluebirds turning their heads through an acute angle as they scanned the ground area immediately in front of them. Even rarer than one of the robins pecking up a worm, though, was one of the bluebirds crashing down to the grass surface in front of them to snag an insect (or worm?). Any success by one bluebird was immediately noticed by the others, and they flew in close to see if there were more morsels in that spot to consume.

Photo by D. Sillman

Off on shrubby edges of the field I could hear a familiar “cheeritt” call. Towhees were calling and hunting in the leaf litter. The towhees have only very recently returned to the park after overwintering in nearby valleys and sheltered areas. They are short-distance migrators that seek out sources of food (berries etc.) to sustain them through the winter. They then return early in the spring to their summer breeding ranges. Towhees have a different way of hunting for their food. They attack a layer of leaf litter with their feet and send leaves and soil flying in a cloud of disturbance. They then jump back and explore the wreckage of their efforts in the hope of having stirred up some worms or insects or almost any other type of small invertebrate or vertebrate. In the summer you often hear this ground and litter scraping and come to recognize it as a sign of nearby towhees.

Photo by D. Sillman

A foraging group of crows flew overhead. They wheeled and turned and filled the air with their raucous calls. You never need to wonder if crows are around! They announce themselves with volume and energy! When I fill my bird feeders in the morning, my local crows are almost always perched in the surrounding circle of tall trees fifty or hundred meters away. Sometimes they watch silently as I fill the feeders and spread their morning favorite, peanuts in the shell! Sometimes they get so excited by the sight of the peanuts that they start bobbing and calling in anticipation. They won’t fly toward the yard until I go back into the house, though. They are loud, but cautious hunters. This hesitation on their part  gives the waiting blue jays (who have been perched out of sight in my line of arbor vitae) enough time to swoop in and grab a few of the crow peanuts for themselves.

Just on the edge of the parking lot a small chipping sparrow hopped from weed clump to weed clump pecking and rubbing at the plant stems with its beak. The sparrow seemed to be hunting purely by feel. Its eyes were open, but they almost looked like they were focused on some faraway object. Its beak did all of the probing and work. I didn’t see any obvious hunting success, but the sparrow’s prey might have been too small for me to see at distance.

Photo by D. Sillman

Finally, a pileated woodpecker flew over the parking lot and landed on the side of a distant tree. The woodpecker immediately started banging on the tree, and I saw some bark and woody debris float to the ground beneath him. It was hard to tell if this woodpecker was hunting and feeding on the insects in this tree or if he was drumming to get the attention of a female. It is a bit late in the spring to start looking for a mate, but hope springs eternal. Woodpecker holes in large, old trees are an important natural nest cavity site for bluebirds (and tree swallows, and chickadees, wrens and nuthatches!). Our bluebird boxes are an artificial substitute for these once abundant, tree trunk and branch cavity sites. As our forest matures, I hope that we let the older, larger trees remain in place so that the woodpeckers can make them into cavity nester’s nest sites!

An hour and a half has gone by. The flicker is still in the same spot eating his ants. The robins and bluebirds are cruising the field in their own ways and at their own paces. The towhees are still calling, but the crows, woodpeckers and chipping sparrow are gone.

Deborah returns from her walk. It is too early for very many spring wildflowers and too cold for the few that are in flower to be open. While we are talking two turkey vultures circle over the car and then wobble away on the light breeze and disappear from sight.

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Signs of Spring 9: Peepers!

Photo byy Well Tea, Wikimedia Commons

I am waiting for a particular combination of meteorological variables. One night very soon, air temperatures will be warm and there will be the deep smell of water everywhere. This night may come at the end of or maybe even in the middle of a day (or three) of steady rain. The ground will be wet and muddy. Low swales will be full of new water. This perfect storm of warm air and water will shake the spring peepers from the last of their hibernation hangovers and stimulate them to start their nighttime choruses in ponds and puddles all over Western Pennsylvania. .

Spring peepers (Pseudoacris crucifer) are small tree frogs that live around marshes, ponds, and temporary pools throughout the United States. Peepers have sticky footpads that enable them to climb up the trees, shrubs, and tall grasses that surround their “home base” water sources, and it is from these perches that the male peepers sing out their distinctive, spring mating songs,

Photo by Fyn Kynd, Flickr

These mating choruses begin in early spring (around here usually in mid-March, but I am writing this during the first week of April and still have not heard them calling). They usually start up fifteen minutes or so after sundown and then call for a four hour period. The calls require a very large expenditure of energy which may explain why the males bunch together to form large, high volume ensembles (even though these groupings greatly intensify mating competition between individuals). The mating/calling season lasts for four to eight weeks. Male peepers begin to sing when they are three years old and the age, size, and overall health of the frog greatly affect their calling frequency. Vigorous or dominant frogs may take the lead in these group choruses and thus stand out among the crowd for the attracted females. The temperature of the evening also affects calling patterns. On warmer evenings the frogs call much more frequently.

A paper published this past January about some tree frogs in Europe (Conservation Biology January 11, 2017) showed that human generated noise (like road noises) can increase stress levels in tree frogs and cause a decline in both their immune functioning and chances for reproductive success! Elevated levels of stress hormones can increase susceptibility to disease (the major cause of the on-going, worldwide extinction of amphibians (see Signs of Fall 5, October 6, 2016)). It can also cause a diminished coloration of the male’s vocal sac (a prime clue to females of health and vigor of the male).

Photo by B. Gratwicke, Wikimedia Commons

Females, attracted to the calling of the males, enter the calling area and select the individual with whom they want to mate. The male then clasps himself onto the female’s back and remains there as the female return to the water source to deposit her eggs. The attached male prevents other male from mating with the female and insures that all of the female’s eggs will be fertilized by his sperm. The female can lay between 800 and 1000 brown-colored eggs either singly or in clusters. The eggs may be set afloat in the pond water, attached to submerged vegetation, deposited in the muddy bottoms of pools, or even put into fluid filled tree hollows or many other types of available micro-pools.

The eggs hatch in six to twelve days. The emerging larvae (the “tadpoles”) will typically remain in their aquatic form for ninety to one hundred days. This larval incubation period, however, can be as short as forty-five to sixty days depending upon weather conditions, time of egg deposition, and conditions in the tadpole’s pool. Populations of peepers developing in temporary pools may be undergoing selection for shorter and shorter larval incubation times. The devastating impact of a tadpole pool drying up is an unforgiving selection force!

The tadpoles eat a wide variety of foods (including algae, dead vegetation, bacteria, fungi, zooplankton, flesh from animal carcasses, and even inorganic materials like sand). The tadpoles are, in turn, preyed upon by almost any organism that is larger than they are. Fish are especially significant tadpole predators in ponds, but predaceous beetles, salamanders, and water snakes also readily consume the tadpoles. Further, pesticides and other pollutants (including acid rain) are significant agents of mortality in spring peeper tadpoles.

Photo by Short Bus, Wikimedia Commons

The metamorphosis of the tadpole into a frog begins with the appearance of hind limbs which is followed by the emergence of the forelimbs and the shrinkage of the tail. Jaws with teeth, eyelids, mucous glands in the skin, and finally the transformation of the light cartilaginous skeleton of the tadpole into the denser, bony skeleton of the frog complete the metamorphic transition into a tiny frog. The emergence of the frog onto land then exposes it to even more predators and environmental dangers.

The frogs are readily eaten by snakes, turtles, birds, and mammals like chipmunks and muskrats. They are also frequently killed on roadways by passing cars and trucks. Peepers are also susceptible to many viral and bacterial illnesses, exhibit a wide range of benign and cancerous skin and mucous membrane tumors, and are beset by a wide range of endo- and ectoparasites (including tapeworms, flukes, nematodes, protists, and larvae of several dipteran species.

Destruction of their aquatic habitats and even more subtle alterations of the forest cover around their wetland breeding sites can also negatively affect the breeding potentials and survival of these frogs.

H. crucifer Photo by USGS (Public Domain)

Hibernation is even a dangerous time for the peepers! While they are hibernating under soil and leaf litter, in and under rotting logs, and even under rocks, they are often exposed to sub-freezing temperatures. They are able to survive these freezing events by generating large quantities of blood glucose from their livers. This sugar (like we have seen in wood frogs and tree frogs) acts as a natural anti-freeze in their blood and other body fluids. Survival during these sub-freezing events is inversely related to the duration of the exposure (85% of the frogs survive after three days of freezing, about 50% survive after seven days of freezing, and 0% survive after twenty-eight days of freezing). While in hibernation, the peepers may also be preyed upon especially by small mammals active in the subnivian space beneath the snow cover. Shrews in particular readily consume the inactive, hibernating frogs. Long, cold winters, then, via extended lethal freezing and increased predation opportunities can have significant impacts on the population of this important sign of spring!

All of this tells me that it is very hard to be a small frog!

I am at this writing still waiting for the first sound of this spring’s peepers! If anyone has heard them already, please let me know. Let’s get this Spring going!

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Signs of Spring 8: Domesticated Us

Photo by D. Sillman

A few months ago I wrote about the latest research describing the domestication of dogs. The next week I looked at our “other” best friend (cats) and concluded that, possibly, cats never were domesticated but they may, in fact, have domesticated us! It all depends on how you look at our relationships, really.

The idea that domestication is not just something people do to other species but might, in fact, be a two-way street stuck in my mind. It led me to accumulate an array of research papers about the genetics of domestication (looking mostly at the history of agriculture and the 14 wild animal species and 100 or so wild plant species that humans have incorporated into our agroecosystems). I also read some of the more recent literature about “re-wilding” ecosystems (George Monbiont’s articles and his book, Feral, were very significant here).

Photo by WolfmanSF Wikimedia Commons

Monbiont’s stated desire is to erase domestication and return as much of Earth as possible to a state of pre-agricultural existence (a time of woolly mammoths, wild forests, and powerful, free-roaming predators). His ideas feel like a new (and more extreme) version of the “back to nature” philosophies of the 1960’s and early 1970’s (“we got to get ourselves/ back to the garden,” as Crosby, Stills and Nash (and Young, I think) sang). The counterculture of the 1960’s, though, envisioned gardens, orchards and farms as the natural state of human beings. This new, twenty-first century vision takes us back before those pastoral Eden-esque communes into the isolated caves and shelters of our hunter-gatherer ancestors.

Are we ready to huddle by the fire at night listening to the sounds of passing carnivores? Are we ready to spend nearly all of our waking hours gathering dispersed foods from our ecosystems? How would the meager resources of the Earth support such a large, “natural” population of humans, and, considering what domestication and agriculture have accomplished (and done to us!) is a return to such an existence possible? Has an evolutionary door closed on that kind of human existence, and, if so, should we thankful that that door has closed?

We need to think about the process of domestication from the perspective of plants and animals and then apply these ideas to ourselves.

Public Domain

Domestication is a process that changes the genetic makeup of a species. Animals like dogs or cattle, goats or chickens do not simply learn to tolerate humans, instead they become physiologically adapted to not feel the stress that wild species experience when coming into contact with such an unpredictable (and dangerous) organism like a human being. Domesticated animals also do not experience stress if they are kept in space-limited enclosures or if they are raised in huge herds or flocks.  Animals that can be domesticated must also have food needs that can be provided by people and reproductive rates and growth rates that will allow efficient accumulation of individuals in a sustainable herd. They must also breed in captivity and not be terribly aggressive or vicious.

Not many animal species satisfy all of those requirements, and that is why so few animal species have been domesticated! Failure in even a single feature makes the species impossible to domesticate.

Wild cabbage. Photo by MPF, Wikimedia Commons

For plants to become domesticated, there must be a way to exaggerate the growth of some part of the plant for the benefit of the human consumer even if the plant itself might be ecologically crippled by the changes. Wild cabbage (Brassica oleracea) is a great example of this exaggerative selection. Wild cabbage is a member of the mustard family and has a very efficient overall structure that enables it to grow, reproduce and thrive in many uncultivated ecosystems. It can be quite a successful “weed!” Variations among individuals in wild cabbage populations, though, have been exploited by humans and used to select versions of this plant with highly exaggerated and, probably, not terrible functional leaves (like domesticated cabbages and kales), or exaggerated stems (like Kohlrabi), or large, slowly maturing flower stalks (like broccoli and cauliflower) or buds (like Brussel sprouts). None of these domesticated forms of the very efficiently constructed wild cabbage could survive in the wild, but they flourish under the care and husbandry of humans.

Photo by Cliff, Wikimedia Commons

Domesticated grain plants are even more extreme in their genetic transformations. Wild wheat and barley, like the domesticated forms, make clusters of seeds at the top of their stalks. The wild plants, though, spontaneously shatter these seed clusters spraying the seeds out around the parent plant. A mutation in these grain species stops this seed dispersing/shattering event and keeps the carbohydrate rich seeds in efficiently harvestable clusters. For a wild plant this mutation is fatal: the plant is not able to release and propagate its seeds! For domesticated wheat and barley, though, humans gather (and eat) the seed clusters and save enough seed from them to sow during the nest season. The plant, then, succeeds in its human-manipulated ecosystem!

So what has happened to humans as consequences of all of this domestication? Have we fundamentally changed ourselves, too?

The first evidence of the domestication of wild plants dates back 70,000 years to a site in South Africa where abundant starchy residues have been found on stone tools and relics. The first widespread and sustained agriculture, though, probably dates back 12,000 years to the Fertile Crescent of the Near East (modern-day Iraq, Syria, Lebanon, Israel and Jordan). David Reich (a geneticist at Harvard Medical School) recently analyzed human remains from this area that were between 8,000 and 10,000 years old. One of Reich’s observations involved the changes in the nature of the human gene pool. Humans 10,000 years ago existed in discrete and isolated genetic clusters, but by 8,000 years ago these diverse clusters had vanished. Humans, because of flow of products and people due to agricultural commerce, had become a homogeneous, genetic entity. Agriculture, then, simplified and reduced the diversity of the entire human genome!

Photo by C. de la Ganne. Wikimedia Commons

What else has happened to people over these past 10,000 years of exposure to domesticated plants and animals? We have developed genes designed to digest the abundant carbohydrate foods that agriculture generates (and so have our dogs!). We have even developed genes to sustain our ability to digest milk sugar (lactose) well past childhood. Our close contact with large herds and flocks of domesticated animals (along with our increasing numbers and tendency to live in dense aggregations (which in itself may have required a series of genetic changes!)) exposed us to many epidemic diseases that originated in those animals. These diseases include measles and tuberculosis (from cattle), influenza (from pigs and ducks) and smallpox (from either camels or cattle). These diseases changed the genetics of our immune systems and even our blood types via extremely aggressive and pandemically destructive selection!

Further, especially when living in large aggregations, humans required fluid sources that were free of bacteria and other contaminants and, so, developed beers and wines (and the agricultural systems to produce them!). These beverages were safer drinking alternatives than untreated water. Genetic changes then came about to allow people to more safely and efficiently metabolize these sources of alcohol.

So, the “human” that lived as a pre-agricultural hunter-gatherer was a very different organism that the one that we are today. In just 10,000 years our genes have been significantly altered by our changing food resources, living styles and by our exposure to diseases. I am not sure that many of us would survive if we had to return to the “good old days!” Although everyone likes to sit around a campfire!



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Signs of Spring 7: The Day of Amphibians!

Photo by D. Sillman

Last Saturday was forecast to be warm (70 degrees here in Apollo) and only “iffy” rainy, so we decided to schedule out annual Spring trip to Ohiopyle with Rob and Michele Bridges to check out the vernal pools and the emerging and reproducing wood frogs (Rana sylvatica). We planned to meet at the Ohiopyle train station at noon, so we had a little time to get some work done at home before we made the hour and a quarter drive to Ohiopyle.

One of the “home tasks” I needed to accomplish was cleaning out the long drain at the bottom of my driveway just outside my garage door. My garage is under my house and when it rains my driveway turns into a whitewater stream with all of the surface water from my street and from my across-the-street’s neighbor’s uphill driveway. The deep drain at the bottom of my drive shunts all of that water out into my field. That drain, though, also regularly fills up with leaves, and, so, in anticipation of Spring storms, it needed to be cleaned out.

I lifted up the iron cover grate and shoveled out wet leaves and an inch or so of oozy sediment into my wheelbarrow. I saw a couple of large nightcrawlers (Lumbricus terrestris) in the ooze but left them in the mix. They would thrive out in one of my leaf piles. In the last shovel-full of leaves and odoriferous sediment, though, I was very surprised to pick up a very large (seven inches long), robust, dark colored salamander! I quickly put her (I am assuming that it was female because it was so large) back into the standing water of the drain and added some leaves to give her a place to burrow in and hide. She was a slimy salamander (Plethodon glutinosus) (pictured above), the same species we found last September under one of our new landscaping rocks that we had set above our reconstructed driveway wall (see Signs of Fall #5, October 6, 2016).

Slimy salamanders are well adapted to very transient pools of water. The female lays her eggs in the spring pool or puddle in clusters of four to twelve eggs. She then guards them until they hatch (which can take up to three months). The hatchlings, though, unlike most salamanders, emerge as fully terrestrial animals. They is no aquatic “tadpole” stage and, therefore, no need for the spring pool to persist while the larvae grow legs and lungs! The hatchlings of the slimy salamanders scramble up and out their birth pool immediately and head off to feed on tiny insects and other invertebrates. If they survive, they will then be able to reproduce in two of three years.

I did not see any egg clusters while I was cleaning out the driveway drain (I even went through my wheelbarrow of wet leaves to make sure!). My hope is that Ms. Slimy will not be put off by my re-modeling of her nursery pool and will lay and watch over the next generation of these beautiful amphibians.

Photo by D. Sillman

Then Deborah and I drove down to Ohiopyle to meet Rob and Michele. Every Spring we walk the trail that wraps around Ferncliff Peninsula looking for vernal pools and especially for wood frogs. In late March 2013 we timed our visit perfectly and actually saw wood frogs blasting out of their hibernation burrows (they literally were flying up into the air like they were shot from a canon!) and splashing down into their vernal pools. That afternoon pools all over Ohiopyle were full of quacking wood frogs, eggs masses and vigorous frog mating! For the last couple of years, though, warm, dry spring weather has cut into the volume of the pools, and we have seen no adult wood frogs on our walks (although last year (2016) we did see egg masses and tadpoles in the rock pools along the river). All of the upland pools, though, were dry or choked with algae and sediment. This year’s late winter and early spring have been a roller coaster of rising and falling temperatures, but the lower than average snow cover and scanty spring rains didn’t hold much of a promise of surface water and frog pools, but you never know until you go and see for yourself.

We hiked along the Great Allegheny Passage Trail, crossed the river on the beautiful pedestrian bridge and then cut down off the trail to the rocky, riverbank. Along the trail great patches of colt’s foot (Tussilago farfara) (pictured above) were in bloom in the sunny spots in between the large boulders. This familiar, dandelion-like yellow flower is often one of the first blooming signs of spring, and its yellow color is a welcome contrast to the browns and grays we have seen all winter.

Photo by D. Sillman

We walked along the trail and found, up from the river’s edge, right at the base of the rocky cliffs, several pools of water that were alive with wood frogs! The larger females languidly floated near the pond edges and were surrounded by frantically darting, smaller males who were trying to check out as many females as possible. All of the frogs were “quacking” furiously! In the very center of the pool was a clump of dead leaves onto which several egg masses were attached. This was the pool in which we saw tadpoles last April, and it looks like it was once again an active spot

Photo by D. Sillman

for wood frog procreation. Rob saw a red-spotted salamander in an adjacent pool (an eastern newt (Notophthalmus viridescens)?).

This was a wonderful day for amphibians! Two different salamanders and dozens of wood frogs!

We continued on our walk but did not see any more amphibians. We hiked up onto the backbone of the peninsula on a trail that cut through dense stands of rhododendrons and hemlocks. The

Photo by D. Sillman

rhododendron bushes were covered with tightly closed flower buds. In a month this trail will be glorious with white rhododendron blooms! We hiked past the deer fence enclosure and saw the thick stands of tree seedlings growing in its protected space. This forest would look very differently if deer could be kept from eating all of the tree seedlings and saplings!

We got up to the top of the trail and found the pool areas that had been so active with frogs back in 2013. Unfortunately, they had very little water in them and were clogged with algae and debris. No frogs here at all! Something needs to be done to rehabilitate and protect these valuable pools!



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Signs of Spring 6: Caffeine and Coffee Trees

I have written about caffeine before. It is a wonderful chemical with many roles in nature including acting as an attractant for pollinators and as a protection against pests and pathogens. That it also helps us wake up in the morning is just one of those wonderful connections with nature!

Photo by A.C. Moraes, Wikimedia Commons

A recent paper published in the Proceedings of the National Academy of Science (September 20, 2016) describes the biochemical steps and controlling enzymes by which a diverse set of plants synthesize caffeine. The plants included coffee, tea, cocoa, citrus (specifically orange trees), and guarana (a climbing vine native to the Amazon Basin that makes fruit incredibly rich in caffeine (pictured to the left)) (Guarana, by the way is used in a variety of energy drinks including Monster, Full Throttle and Red Bull!). The authors of this paper found that there are subtle metabolic differences between some of these caffeine producing plants. Coffee and tea, for example utilize the same basic biochemical synthesis pathway to make their caffeine except for their final enzymatic step.  They also found that there are some very large differences in some pathways. Cocoa, orange and guarana, for example, not only start their synthesis processes with different substrates but also generate very different intermediate molecules on their way to making caffeine.

Their conclusions were that these plants, which are very distantly related to each other, evolved their caffeine synthesizing pathways independently of each other. This type of evolution is called “convergent evolution.” Its occurrence emphasizes the utility of caffeine as a plant secondary compound. This research also emphasized that MANY plants are potential sources of caffeine. This may be very significant considering what our next set of papers and reports are very clearly telling us.

Climate change has, unfortunately, become more of a political topic than a scientific one. The sad consequence of this is that the political acrimony associated with the debate clouds the reality of the scientific observations of global warming and prevents the taking of any real steps by which the on-going heating of our planet might be delayed or even reversed.

Photo by DirkvdM Wikimedia Commons

A report (“A Brewing Storm: The Climate Change Risk to Coffee”) published in September 2016 by the Climate Institute (an Australian non-profit organization) explored the impact of climate change models on the global distribution of coffee trees. They found that projected rises in global temperatures would reduce coffee producing land areas by 50% by 2050. Impact of climate change (which includes not only rising average temperatures but also changes in weather patterns and cycles of drought and excessive rainfall) were especially severe at low latitudes and low altitudes. The worldwide, tropical “bean belt” will need to move out of the afflicted tropical zones and up mountainsides in order to find suitable sites to grow coffee. It is estimated that there are 120 million people in these zones whose economic livelihoods depend on coffee.

Photo by F. Rebelo Wikimedia Commons

Coffee trees need very stable environments to grow and thrive. This has been one of the ongoing arguments in favor of planting coffee trees under a taller, cover forest. The micro-environment of these “shade coffee” sites are much more stable and predictable than open growth coffee plantations. This how wild coffee grows in its natural ranges in Ethiopia. This is also how most coffee was grown until the mid-Twentieth Century when sun-tolerant varieties of coffee were developed. These great, open, single crop plantations of sun-tolerant coffee produced higher bean yields but at the cost of increased demand for fertilizers and pesticides, increased soil erosion, and the catastrophic loss of forest habitats especially for birds.

The recent awareness of the multiple benefits of shade coffee have included not only an economic side (lower production costs), an ecological side (establishment of complex habitats for birds and other animals), but also an aesthetic side (shade grown coffee tastes better!). Climate change, though, is too much even for these coffee ecosystems!

Photo by Carvalho et al., Wikimedia Commons

Plant diseases are already ramping up on the edges of the global “bean belt.” In 2012 almost half of the coffee plantations in Central America were afflicted with the “coffee rust” fungus, Hemileia vastatrix. Coffee rust is a disease native to East Africa that has spread to all coffee producing countries around the world. It grows and disperses explosively in warm, wet environments (just the environmental conditions predicted by climate change models). Coffee rust has already reduced Guatemala’s coffee production by 85%!    The coffee borer beetle (Hypothenemus hampei) is also a currently significant pest that causes hundreds of millions of dollars of damage to coffee beans. This beetle is originally from Angola but spread early in the Twentieth Century to the rest of Africa and is now afflicting coffee trees in South and Central America and even Hawaii. The moister conditions of a world altered by climate change will allow this beetle to spread even more rapidly through a plantation and across broad geographic areas.

Coffee production is an important part of the economy of Tanzania. Temperatures, though, in Tanzania have been rising since the middle of the Twentieth Century and each degree of temperature rise has been correlated with a decline in coffee production. Coffee production in Tanzania has gone down by 50% since 1960 and is projected to be only a minimal part of the country’s agricultural output by 2060!

As I mentioned above, wild coffee (“coffea”) is a shrub native to Ethiopian cloud forests. There are a number of species of coffea found throughout Africa (including Madacascar and Cameroon), but the origin of our coffee trees are probably from the Ethiopian plants. Another consequence of climate change is that these coffea shrubs are very likely to become extinct before we get to the end of our current century. The loss of this genetic information could be devastating to the future of our cultivated coffee trees.

We can make caffeine in a factory, and we can cultivate some of the other types of plants to make caffeine rich infusions and beverages. I would prefer, though, a world in which we can still get a real cup of coffee.


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Signs of Spring 5: Harrison Hills Walk and Cavity Nesting Team (3.0)

Photo by D. Sillman

Last Thursday Deborah and I headed up to Harrison Hills Park in northern Allegheny County to take advantage of a few hours of sunny, spring weather before the next cold front (and set of snowstorms) blew in. We wanted to get at least one hike in during our Spring Break!

It was a beautiful morning: sunny, in the fifties (with a slight change of warming up close to sixty!). Only the wind made us think of the coming storms. There was an article in this week’s New York Times in which data on “first leaf” emergence from observers all over North America were compiled into an animated map. The wave of “first leaves” surged up the breadth of the country a full three weeks ahead of the thirty year average! It is an early spring this year, a VERY early spring!

We parked near the Environmental Learning Center and headed out across some open, grassy areas to find the first group of our nest boxes. The soil was wet and oozing underfoot and there was flowing surface water running from a number of seeps and springs. The water supported a thick growth of moss (in many places there was much more moss than grass). Small, black Pardosa spiders ran about on the soil and plant surfaces. We hoped that they were getting out of the way of our footfalls!

Photo by D. Sillman

Our boxes were in good shape and had weathered the winter very well. We were especially interested, though, in the direction that their access holes pointed. Last year, 9 of our 28 nesting boxes had house wren nests (no boxes from our 2015 study had had house wren nests). Six of the 9 house wren nesting boxes had been previously nested in by bluebirds (4 boxes) and chickadees (2 boxes). House wrens and bluebirds have many similar nesting characteristics: they tend to nest in two seasonal cohorts (early spring (May) and late summer (July/August), and they tend to select nesting sites no more than 50 to 100 feet from a wooded edge. Possibly our 2016 box relocation project moved a significant number of our boxes into nesting sites also preferred by house wrens.

The problem is house wrens are one of the most common causes of nest failure in bluebirds, tree swallows and chickadees. House wrens destroy eggs, kill nestlings, and even kill adult birds so that they can then start their own nests in the usurped box. Also, male house wrens attempt to attract females by building numerous “dummy nests” (piles of sticks sometimes piled on top of the active nests of other birds!). These dummy nests are an important sign of house wren activity and can be used to thwart house wren nest invasion. Since these dummy nests contain no eggs, they can be removed from the nest boxes without violating the Migratory Bird Treaty’s protections of native bird species. Prompt removal of these stick piles may keep a male house wren occupied in re-building the displays rather than getting down to actual reproduction.

Photo by dfraulder, Wikimedia Commons

Also, the literature on “wren guards” (various nest box modifications that are designed to repel house wren nest box invaders) stresses that it is the visual cues of the nesting birds entering and leaving a nest box that are the critical stimulations that then trigger the house wrens to attack the active nest.  Possibly, turning all house wren utilized nest boxes to point their openings away from the surrounding woods (where the house wrens spend much of their time foraging for food and hiding in the covering vegetation) would make the visualization of the nesting birds entering and leaving the nest box less apparent and decrease the rate of house wren infestation. Re-orienting the boxes was one of the tasks that Deborah and I hoped to accomplish today.

We looped through the meadow near the purple martin houses and then hiked up into meadow on top of the nearby hill. I walked up to the “High Meadow” on a narrow path that cut through the woods while Deborah took the longer (but less likely to have ticks) route back down to the access road than ran from the Learning Center. I scared up a bird  from the dense vegetation along the path as I walked along. The sudden rise of the bird was noisy and very exciting!  I think it was a grouse but it moved so rapidly that I did not get a good look at it. I also picked up a black-legged tick (which Deborah found working its way up my pant leg when we stopped to do a tick-check up in the High Meadow). It is the time of year to be very watchful!

We finished the High Meadow and the nearby Bat House Meadow loop doing some small repairs on the seventeen boxes and their poles and turning each box so that it faced away from its surrounding trees. One box in the Bat House Meadow had a metal, predator guard on its pole. We remembered that that box was the one that had the black snake inside of it when Sharon (one of the Cavity Nesting Team) open up the box to check on a swallow nest. The snake had eaten the swallow nestlings and was napping inside of the box. Good adrenaline rush, I am sure! The guard should keep that from happening again.

Photo by D. Sillman

Five male bluebirds followed us around in the Bat House Meadow. They are the first bluebird arrivals (or, maybe, the hardy, overwintering individuals?) and are checking out and competing for optimal locations for their breeding territories. Plenty of boxes for everyone, boys! The females should arrive in a couple of weeks

We then drove to the park entrance and checked the two boxes set on a fence line just to the south of  Y-intersection of the two park roads. Both of these boxes had predator guards and both had old nest materials in them. Possibly some overwintering bluebirds had built some nests, or some late fall swallows had done some practice nest building. The dry grasses were not tightly woven together and there were few feathers and very little feces in either box. There was no evidence of any recent activity. We cleaned them out and packed away the debris.

Photo by D. Sillman

The road to the soccer fields was closed so we had a long walk from the upper parking lot down to the cluster of boxes set around the field edges. We turned each box to face away from the surrounding trees. The wet soil of the soccer fields were blooming with the tiny white flowers of Pennsylvania bitter cress (Cardamine pensylvanica), and in the even wetter areas along the flowing drainage ditches and streams, the mottled purple, tear-dropped shaped spathes of skunk cabbage (Symplocarpus foetidus) grew in dense clusters.

Photo by D. Sillman

One of our nest boxes was missing! “Box V” that had been set next to the pond just up from the soccer fields was gone. This had been an important tree swallow box in both 2015 and 2016. We will have to locate it or replace it before swallow breeding season starts in late May.

We hiked back up the hill to the parking area through the woods that bordered our two nest boxes that had no nesting activity either in 2015 or in 2016. We left the boxes in place, though, because these two meadows seem so perfect for bluebirds (or chickadees or nuthatches or swallows). There is something, though, about these two sites that birds don’t like. We will have to figure out what it is!

The shrubs and trees on the pond side of the uphill climb were covered with American bittersweet vines (Celastrus scandeus). A few of the vines still had some of their distinctive, orange, pea-sized berries on them. These berries are poisonous to people but are a very popular winter food for birds. January before last we were hiking on this path and were amazed by all of the overwintering robins that were there. They must have been living on these very abundant, bittersweet berries.

Bluebird season will start the third or fourth week of March! The boxes are ready, and the Cavity Nesting Team will be there to watch and report!

Happy Spring, everyone!

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Signs of Spring 4: Earthworms on the Sidewalk!

NASA, Wikimedia Commons

The full moon of March (which this year will occur on March 12) has many names. The Algonquin’s called it the “catching fish” moon, while the Omaha and the Cree called it the “little frog” or just the “frog” moon (we will have to wait a few weeks more, though, before the frog choruses begin to grace our evenings!). The Kiowa called it the “bud” moon, and several other tribes referred to it as the “crow” moon after the increased vocal activity of the flocks of crows as they sorted out their social and reproductive hierarchies after the long and stressful winter. A number of the northern tribes called the March full moon the “crust” moon after the icy snow crusts that form on the persisting snowpack due to the daytime thawing and nighttime re-freezing of the surface. They also called it the “sap” moon after the rising sap of the trees (especially the sugar maples!) which, interestingly, is caused by the same daytime warming and nighttime freezing cycles that cause the snow crusts.

The name most frequently applied to the full moon of March today, though, and attributed to Native American sources (although never in my readings to a specific tribe), is the “worm” moon.

Photo by H. Casselman, Wikimedia Commons

Walking out on last week’s warm, wet mornings, the “worm” moon appellation seems quite appropriate. On almost every sidewalk, driveway, or parking lot a significant number of “earthworms” of various species were wiggling along on the wet surfaces, moving in apparently random directions out from their former burrows in the surrounding grass. Why are so many worms emerging all at once? The emergence is probably a behavioral response to moisture and temperature variables that helps to disperse and expand the boundaries of an earthworm population (no, they are not drowning in the wet soil!). As earthworms reproduce and their clustered cocoons hatch the new worms tend to be clumped together, the spring dispersion helps to spread their numbers out across a soil habitat.

Photo by R. Bushby, Wikimedia Commons

The arrival of the migratory flocks of robins is coincident with this worm emergence event. Watching the foraging robins voraciously eating worms really gives you a good idea of how many earthworms are actually slithering along on or just hiding beneath the soil surface. Many bird species (including the grackles that just showed up under my bird feeder last week!) also opportunistically, and with less time and effort investment than the robins, catch and consume earthworms. European starlings, an alien invasive bird species, have even been known to follow the hunting robins at a distance and then, on seeing a robin grab a worm, dive at them noisily so that the worm is dropped when the startled robin flies away. The starlings, then, get a stolen, protein-rich, meal. This is only one of the ecologically disrupting things that starlings do, but that’s a topic for another essay.

As many of you know, I studied earthworms very intensively in my Ph.D. research and in a variety of studies here at Penn State back in the 1980’s and early 1990’s.  A “worm” moon, then, should have some special meaning to me, and, I admit, it does. It is not at all clear to me, however, how Native Americans could have had any ecological or historical connection to these earthworms! Almost all of the organisms we call “earthworms” are, like the European starling and the gypsy moth and Colt’s foot and so many other species of plants and animals around us, organisms that were introduced to North America by European settlers as they spread across the forests and plains of the continent. Earthworms are a group of alien, invasive species!

Photo by S. Shepherd, Wikimedia Commons

Earthworms do many important things in their soil habitats. They improve the stability of a soil’s structure and its drainage properties, and they accelerate rates of leaf litter decomposition and nutrient cycling. Aristotle called them “the intestines of the Earth,” and Charles Darwin spent many years of his life intensively observing and describing their activities and their extremely positive influences upon soil fertility. My own research described the immense benefits that robust populations of earthworms could have on leaf litter decomposition in established forests ecosystems and on re-forested strip mines, and in the cycling and rehabilitation of sewage sludge.

A few years ago, though, an article in the Science section of the New York Times described some of the more negative consequences of the extremely active shredding and burying of leaf litter in worm rich soil ecosystems. Earthworm activity leads to the loss of leaf litter habitats for a wide variety of other invertebrates. It also leads to the loss of the protective, soil covering leaf litter “blanket” and changes the nature of the soil community’s nutrient and energy webs. Earthworm activity also changes the way that organic materials are distributed through the soil profile. The soils of what seem to be undisturbed ecosystems are, in fact, irrevocably changed from their original conformations by the actions of the introduced earthworms.

So, how could Native Americans describe the mass emergence of earthworms in the spring and relate it to the March moon if these earthworm species didn’t arrive in North America until possibly the Seventeenth or even the Eighteenth Centuries? I don’t think that they could or did, and careful examination of lists of specific tribal moon names backs up this idea. No specific tribal designation for the March moon includes the “worm” moon.  Fish, frogs, buds, crusts, crows and more are listed, but no worms. My feeling is that the “worm” moon is, like the worms themselves, an imported thing brought by the settlers from their European homes that quickly became incorporated into the structure and perceived history and ecology of their new environment.

Did the increased abundance of the earthworms lead to increases in American robins and other earthworm eating birds? Did earthworm activity change forest soil properties to favor different tree species? Did the cleared land plowed into farm fields become more productive because of the swelling numbers of earthworms? Did the earthworms cause the extinction of some litter dwelling beetles and other insects? Did the activities of these extremely active earthworms drive native annelid species into their very restricted present day distributions?

What interesting ideas! Something to look at in my retirement!

Happy worm moon, everybody!


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Signs of Spring 3: Tree Buds and other Emergences

Photo by D. Sillman

The branches of the silver maple at the bottom of my field are covered with flowers (photo to the left). Last week’s warm weather stimulated the opening of the flower buds a good two weeks before “normal.”  If the early spring holds on, the leaf buds will be opening soon, too. This tree is always the first one to flower up on our hill. It is definitely an important sign of spring!

There are also four, large red maples close to my house (photo below). They typically flower a week or two after the silver maple. A cold, lingering winter (like the one in 2015) can push this flowering to early April, but usually by mid-March the little, red flowers open up first on the tree nearest the street (I think that it’s warmer there) and then on the trees clustered more toward the middle of my field. When the red maples bloom the honey bees begin to swarm and local beekeepers start to see red maple pollen in the honey in their hives

Tree buds are structures that encase and protect the forming flowers and leaves. The outer part of the bud is made of tough scales that form overlapping, shingle-like structures around the delicate leaf or flower growth tip. These bud scales keep out destructive insects and also insulate the inner tissues. These scales are, really, very tiny, very tough, highly modified leaves. Buds are classified as to whether they encase flowers (“floral” buds), or leaves (“vegetative” or, simply, “leaf” buds), or both floral and leaf embryonic tissues (“mixed” buds), and by their position on a branch (“terminal” buds are found at the end of a twig and “lateral” buds are found along the sides).

Photo by D. Sillman

On silver and red maple trees most buds are either floral or vegetative. The floral buds are larger and spherical and the leaf buds are smaller and more oblong. The floral buds are also typically clustered together in bunches on the twig. Over the winter I have watched squirrels nipping off the lateral buds on the red maple branches (they must be a welcome dietary supplement to balance out all of the sunflowers seeds they had been eating from my bird feeders!). Most of the branches, though, were too thin for them to get out to the terminal buds, so I expect to see both flowers and leaves concentrated at the ends of tree branches this spring and summer.

As I said, the floral buds on the silver maple just opened and soon, if this warm weather holds, the red maple buds will open revealing the delicate clusters of red and yellow flowers. The tiny pollen grains from these flowers will then be spread mostly by the wind (although honey bees, as I mentioned before, will be visiting some of these flowers). By chance some of the wind-blown pollen will encounter ova in the ovaries of other flowers and accomplish the fertilization phase of the reproductive life cycle. The pollen is produced in prodigious amounts by these trees, and you can easily understand why. The probability of a given pollen grain, randomly dispersed through the atmosphere by the wind finding an appropriate ovum is infinitesimally small!  To insure that fertilization occurs at all, the trees must fill the air with pollen. Human interactions with this pollen mass can generate allergic reactions in sensitized individuals. Hardwood tree pollen, in general, is a major spring allergy trigger. Dripping noses and red eyes, unfortunately, come with the season.

Photo by Dcrjsr, Wikimedia Commons

Once an ovum is fertilized it will develop into the maple tree’s distinctive winged seeds (their “samara”). These “maple keys” will, by early May or so, form great, fluttering clouds as they drop from the trees and become scattered by the wind across lawns and woodlots. A large red maple tree can produce over a million of these seeds each year! Some of these seeds will germinate immediately while others may lay dormant in the soil until the following year. Many of these seeds will be eaten by birds and squirrels. These seeds and their seedlings are topics for a summer essay (and (great news!) summer is not that far away!)

Out in my front yard bird feeders at night there have been some regular visitors throughout the winter. The deer, of course, come in numbers to clean out any corn that hasn’t been eaten by the crows or jays or gray squirrels. They also like to use their noses to tip up the sunflower feeders to get a big mouthful of those (very expensive!) seeds! A possum has been a regular all winter. He digs around in the spilled seed beneath the feeders and always seem confused and frozen in place if I turn the yard light on.

Since January, I have been smelling skunks when I take Izzy out for her morning walk. I haven’t seen a skunk in quite a while, though. They must be coming in very late at night. Two nights ago I saw someone whom I hadn’t seen for months: a raccoon! They are regulars in the summer, but either this raccoon got very hungry hanging out in his hollow tree or the warm night made him think that spring was upon us. Raccoons don’t hibernate, but they do power down in cold weather and sleep in their tree or ground dens slowly metabolizing their stored fat reserves. This one had found some leftover corn which he continued to confidently eat even after I opened the porch door, shone my flashlight on him and said “hello.”

Photo by N. Townsend, Flickr

There have been more bird songs in the mornings and through the afternoons. Cardinals are singing their territories, and titmice are whistling for mates. Mourning doves begin calling well before dawn, and chickadees are joining in. White throated sparrows are still singing as are the Carolina wrens (they have been going on all winter).

Pileated woodpeckers have been pounding away on the spindly black locust tree out in the back of my yard. I also heard one down on Roaring Run last weekend banging away on one of the tall sycamores on the hill side of the trail. So many other bird species benefit from these tree holes! As someone said, if you want bluebirds (and tree swallows, and nuthatches and chickadees) leave some old trees for woodpeckers to work on!

I haven’t seen any snakes yet this year or chipmunks for that matter. Both of these animals are true hibernators and this transient warm spell probably won’t overcome their evolutionary perspective on our variable, late winter weather. Soon, though, very soon!

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Signs of Spring 2: Hardwood Forests

Photo by D. Sillman

We had a mid-February Saturday afternoon that was 63 degrees and full of sunshine. The skies were a deep “Colorado” blue, and the air smelled fresh and alive. Deborah and I went for a walk down on Roaring Run to stretch out our winter legs and look for some signs of spring.

The Roaring Run trail follows the old Main Line Canal route along the northern bank of the Kiskiminetas River. The canal was built in the 1830’s and almost immediately became obsolete because of improvements in railroad technology. The canal was filled in and covered with railroad tracks which were themselves replaced in recent decades by a really excellent hiking and biking trail. On one side of the trail a short slope drops off steeply to the river while the other side a long hillside rises up to a tall, bordering ridge. The hill up to the ridge top is forested with a mix of fast growing tree species that have filled in after repeated clear cuttings. The original trees were cut in the “timber phase” of Pennsylvania forest use and then two or maybe even three regrowth stages were cut in the Pennsylvania “charcoaling phase.” Red maple, yellow birch, yellow poplar, white ash, black cherry and red oak (with a few sycamores and catalpas thrown in) dominate the forest.

Photo by D. Sillman

The first thing I noticed as we started down the trail was an abundance of downed trees and branches.  Tree trunks were sawed and stacked alongside the trail at the ends of leading trails of fresh sawdust that indicated where they had fallen across the trail path. This has been, overall, a mild winter but there have been enough windstorms to severely thin out the trees. Many of the downed trees were poplars, but many of limb piles were red maple branches. Poplars have soft trunk wood and are easily broken by wind. That’s why you only see old, large yellow poplars in sheltered stands of trees or in deep, protected hollows. Red maples (possibly the most abundant tree of the eastern hardwood forest!) have relatively brittle limbs and branches. I pick up fallen branches under my red maples all year round.

The consequence of this thinning, though won’t be seen for another couple of months. With all of the trees still in their leafless winter aspects, the sunlight poured down to the leaf covered forest floor. You could feel the warming of the litter and soil and the stimulation of seed germination and root growth. All this sunlight will start the growth of the early spring wildflowers and other understory plants (these hillsides are covered with blankets of white flowered trillium in April!). Then the tree canopy leaves will unfurl, and the forest floor vegetation will settle into a shady, cool, moist, low energy dynamic for the duration of the summer and early fall.

Photo by D. Sillman

In the canopy spaces made by the fallen trees, though, the sunlight will continue to warm and energize the forest floor. A race among seedlings of maples, poplars, ashes and cherries that have been subsisting in the shadows of the over story trees begins and the fastest seedling to grow, or the one luckiest enough not to be browsed by deer, will quickly take over the open spot in the canopy. The wind pruning lets the forest reestablish itself. It is an opportunity to start a youthful patch of trees that will live well on into the next century.

Just as Deborah strode on ahead on her walk (she walks faster than I do!), a sudden gust of wind broke a medium top branch from one of the sycamores on the river side of the trail. The branch snapped with a loud “bang” and clattered down through the canopy carrying other, smaller limbs with it. The branches landed in a pile right on the river’s edge. They will be carried away when the river swells up with our spring rains. I am glad that it didn’t fall on my head!

Photo by D. Sillman

I didn’t see any birds on my walk. Deborah did see, though, an old oriole’s nest hanging from a limb of a tall poplar tree. The distinctive basket-shaped nest would be hard to spot when the tree was in summer leaf, but today its stood out clearly against bright blue sky and black, bare branches.

Deborah also saw a small bat (a little brown bat?) flying around the bridge that crosses the Roaring Run stream. It is possible that the past two warm days woke up the bat from its hibernation and that he/she will return to his/her cave when night falls. It is more likely, though, that the bat woke up because of the irritation of the white nose fungus and in a half-awake state had burned through its winter fat stores and was now out of its cave and desperately seeking food. We did see some stoneflies out today, but not enough to feed a hungry bat.

A stone wall alongside the trail in between the two-mile trail marker and the bridge is part of an old lock from the Main Line Canal.  In the summer, this is a good place to look for snakes (I have seen garter snakes, black snakes and even copperheads around here in warmer months). Today the early leaves of Dutchman’s Breeches were visible in the crevices between the rocks. A few years ago a troop of Boy Scouts “cleaned up” this part of the trail and did a great deal of damage to the wildflowers that had been growing in the rock wall.  Thinking that were removing “weeds” the scouts pulled up Dutchman’s Breeches and Indian Corn and who knows how many violets and other spring flowers. Sometimes the urge to make things neat and tidy should be resisted!

Near the start of the trail an informational sign talked about the on-going program to control the exotic invasive plant, Japanese knotweed. The sign talked about a two pronged herbicide application that effectively killed the knotweed. There was a picture of a riverbank choked in knotweed and discussion of the benefit to native plants to have this dense, shading invasive removed. Looking up from the sign, though, all I could see was a forest of knotweed. I don’t think that the chemical offensive was at all effective.

Many people were on the trail today and lots of them had their dogs with them. We met a three month old pit bull and several, more mature terriers, beagles and hard to identify mutts (my favorites!). They seemed to enjoy the warmth and sunshine, too.

I will have to have a long talk with Mazie about her “six more weeks of winter” prediction from House Cat Day. Looks like she (and Phil the Groundhog, too) missed this year’s early spring.


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Signs of Spring 1: Good News and Bad News

Photo by D. Sillman


I have been looking everywhere for signs of spring! Although this has not been a terribly hard winter (here in Western Pennsylvania, anyway), everyone is justifiably sick of the cold temperatures and the gray skies. Also, most of us desperately miss the color green and the morning choruses of the waking birds and the evening trilling of the peepers and tree frogs! We are ready for spring to arrive!

My cat Mazie (pictured above) has decided that we will have more winter this year, though. She fled from the front yard to the porch and ran all the way to the basement when we did our fifth annual House Cat Day experiment!

The three of the first four “Signs of Spring” I have seen are not terribly welcome ones. I guess we have to take what we can get! I’ll start with the “nice” one and then get all dark and gloomy.

Honeybee in bird feeder

Photo by D. Sillman

The bees are awake and “afoot!” On a warm afternoon last week a squadron of honeybees converged on my bird feeders in search of anything sweet and edible! I think that the powdery residue of the shelled corn that I have been putting out for the jays, crows, and squirrels drew the bees in (and hopefully gave them something that they could take back to their hive). The photo on the left shows one of the honey bees checking out the sunflower seeds! It is not energetically beneficial for the bees to go out foraging before there are any flowers, but it was nice to see them after all of these bee-less winter months!

Photo by D. Sillman

A second sign of spring was inside my home: over the past few weeks the distinctive aroma of brown marmorated stink bugs has been rising in unexpected places throughout my house. When we were sitting in the living room in the evening, when I was riding my exercise bicycle in the afternoon, when we were getting ready to feed our dog her dinner, all of a sudden our olfactory senses were overwhelmed by the pungent scent of a stink bug (or three, or four). The bugs were stuck away and hiding in all sorts of nooks and crannies (up in fluorescent light fixtures, under dressers, behind books on shelves, in the labyrinth of all of the cans in pantry, in a pair shoes) and were being roused from their winter torpor, I think, by the warmer temperatures and growing day lengths.

What we are seeing is probably the tip of the hibernating horde of stink bugs! A few will come out to check out the weather conditions and then either wander off to die (or get caught in one of my stink bug bottles) or tuck themselves back into one of their hidden hibernaculae.

The ability of these stink bugs to overwinter is remarkable. There is some mortality among the hibernating bugs, but a significant percentage of even the outside hibernators make it through to spring and to their opportunity to mate. Colder temperatures, though, reduce this percentage of survival. Several models of climate change and global warming have included increased survival of stink bugs at higher and higher latitudes with, then, significantly larger spring and summer populations of this potentially destructive pest. When you factor in their ability to find their way into our houses and spend the winter months hibernating in tiny crevices and hideouts all around us the survival rate goes up to near 100% and the northern, “freeze” boundary disappears altogether.

Photo by Dori Wikimedia Commons

My third sign of spring came from a colleague at Penn State. I got an email from Rob Bridges a few weeks ago in which he described watching some crows feeding on a road killed rabbit out in from of his house (Rob and I have many interesting conversations like this!). As he watched, though, the crows were suddenly sent flying by the arrival of a turkey vulture who then proceed to dine on the pressed rabbit.

This surprised me because turkey vultures that live around here in the summer are expected to spend their winters in Florida or Texas. Our cold winter temperatures would not only put a great deal of stress on the vultures but also prevent the generation of the thermal updrafts that they require to sustain their long, daily flights in which they search for food. Turkey vultures also primarily use their sense of smell to find carcasses on which to feed. Cold temperatures will inhibit both the generation and the distribution of these scent lines!

Turkey vultures are also quite gregarious.  They night roost in large, communal groups and usually forage or day roost in smaller groups (called “wakes”). A turkey vulture is seldom seen without companions! Where are the other members of his wake hiding out?

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 Housecat Day!). But, Lower Burrell, PA has an eight week jump on Hinckley! The vultures are back!

Photo by D. Sillman

Finally, a very unwanted Sign of Spring came in on our dog, Izzy: black legged ticks!

I have removed three ticks over the past few days from Izzy. They were adult, female “black legged ticks” (also called “deer ticks,” but most properly called  Ixodes scapularis). These adult forms had been very abundant back in the Fall and some, apparently, have successfully overwintered and are still seeking the blood meal they need to make their eggs.

Pennsylvania is experiencing an ongoing population explosion of black-legged ticks. The reason for this increase is not precisely known. Possibly the increased populations of rodents (especially white-footed mice) particularly in our suburban ecosystems may be providing the ticks with an abundance of small hosts on which to feed. Black-legged ticks, then, in their larval and nymphal life stages are very likely to find a white-footed mouse from which they can take a blood meal. These mice are also significant reservoirs for the bacterium that causes Lyme disease, so the ticks that feed on them have a very high probability of assimilating and then passing on these bacteria.

The true “spring” blacklegged ticks are the eight-legged nymphs that have been overwintering since last summer. These are the “medium sized” deer ticks and very significantly they may be carrying the bacterium that causes Lyme disease. These ticks will feed on a wide range of mammals (from white-footed mice to dogs to cats to deer to humans). Both dogs and humans are susceptible to Lyme and both are experiencing out of control epidemics of the disease!

So, bees, stink bugs, vultures and ticks! Quite a quartet of Spring! I hope to see some crocuses, red maple flowers and flocks of robins and bluebirds soon, too!



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