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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Signs of Winter 11: Oaks and Acorns

Photo by Jamaine Wikimedia Commons

Oak trees use their acorns to “fly” or “stride” (or hop or run) from one habitat to another. I now have a yard and field with twelve young oak trees (a mix of white, northern red, and scarlet oaks) growing in the places where eight of my forty year old spruces once stood (but which were, alas, knocked down in a June 2006 microburst event). The acorns that started these trees were undoubtedly dropped from the branches of the spruces when some careless blue jay or crow tried to talk with their beaks full. The oak seedlings were quite inconspicuous under the dense branches of the spruces but have now grown into solid looking pole trees that are twenty to twenty-five feet tall.

In 1996 my daughter had a fourth grade science project in which she had to identify the trees of her yard and neighborhood. She and I wandered about on our two acres and up and down our street and identified fifteen or twenty different tree species. We saw, though, no oaks at all! Most of the trees we identified were intentionally planted and placed as the surrounding houses were built in the 1950’s and 1960’s, and a few were orchard relics of an even older, farm-related past. Great swaths of lawn was the dominant habitat type all around us, and there were very few “wild” trees to be seen anywhere.

Twenty-one years later, though, the wild oaks abound on the edges of my property thanks to careless birds and also to my personal abhorrence of weed-whackers and any need for tidiness and control in my landscaping!

Photo by D. Mullen Flickr

Let’s think about oak tree flowers and acorn production (and I am going to focus on white oaks as my example oak species): white oaks flower in the spring right about the same time as they leaf out. Here, in Western Pennsylvania, that is mid-April or so. A given tree will have both yellow, staminate flowers arrayed in dense catkins and red, pistillate flowers that are usually singular or in pairs. The staminate flowers mature a week to ten days before the pistillate flowers (a good protection against self-pollination) and in the three days of pollen dissemination winds can carry the tiny pollen grains great distances. If a pistllate flower gets pollinated it will begin to form it acorn. If it does not get pollinated, it will senesce and drop off the tree. It is possible, then, to get a good idea of the success of a year’s pollination efforts by simply observing the abscission or persistence of the white oak’s pistillate flowers during this critical time period of the spring!

Weather conditions, though, greatly influence the timing and success of pollination. Wet weather slows down pollen release, and dry winds and freezing temperatures can greatly inhibit flower development. Ideal acorn development occurs, according to Sharp and Sprague (from their 1967 paper in Ecology), when the weather is warm for the ten days before flowering and then cool for the two or three weeks after flowering.

Thinking about the extremely variable weather of the month of April, these perfect conditions are not likely to occur very frequently! Interestingly, variability in the production of acorns may be an extremely important feature of an oak tree’s overall reproductive strategy!

Photo by Dcjsr Wikimedia Commons

A mature white oak (a tree between 50 and 200 years old) can produce up to 10,000 acorns a year! That same tree, though, may produce no acorns at all in any particular year, and somewhere in between zero and ten thousand in most of the intervening years. Acorn production (also called “mast production”), then, is quite unpredictable from year to year. On average, a good acorn year (also called a “mast year”) occurs only every four to ten years. These mast years, though, are only partially correlated with the weather and with some of those flower survival and pollen formation factors mentioned above. There seems to be some other, more innate biological process going on in the oak tree that helps to regulate the overall potential for the tree to make acorns.

Which gets me to the reason I am writing this post! Back in November, my good friend from California, Larry, sent me an article from the Wall Street Journal. The Journal is not a paper I regularly read, and it is definitely not a paper in which I would expect to find a very interesting article about oak tree reproduction! However, the November 6, 2016 issue had an article entitled “Boom or Bust Breeding Cycle that Helps the Mighty Oak Survive” (by J. C. McGinty) that beautifully described the evolutionary logic employed by oaks that necessitates great yearly fluctuations in acorn production.

D. Sillman

The idea is very straightforward: acorns (especially white oak acorns) are highly desirable food for many species of birds and mammals (in fact, more than 180 species of birds and mammals eat white oak acorns (everything from crows to turkeys to blue jays, and deer to raccoons to a variety of mice!). In non-mast years almost all of the white oak acorns produced are consumed before they can germinate. The only way that an oak tree can slip a few acorns through this consumption filter is to occasionally overwhelm the system with acorns. It is only in mast years, then, that substantial numbers of acorns survive to form oak seedlings!

Last Fall in Pennsylvania we had, according to Marc Abrams (a Penn State professor of forest ecology and physiology) a “super mast year!” Abrams reported a greater mass of acorns on the red oaks around State College than he had ever seen in his thirty years of observations. Deborah and I had noticed this, too, on our local hiking trails here in Western Pennsylvania. In places with abundant oak trees it was actually difficult to walk because of all of the rolling acorns underfoot! I had to go back in my hiking notes to 2006 (ten years ago! A typical mast-year cycle!) to find references to such acorn abundances.

Photo by D. Sillman

So, there will be a lot of winter food for white tailed deer and wild turkey this year! The Journal article also makes reference to another, less welcome species that is expected to benefit from the acorn abundance: the white footed mouse. White footed mice are one of the key biological reservoirs for the bacterium that causes Lyme disease. The mice pick up the bacterium from black legged tick bites and then pass it along to more ticks that subsequebtly feed on their blood. It is expected that with a booming population of white footed mice in our woods and fields, a higher percentage of black legged ticks will be exposed to the Lyme bacterium and thus potentially carry the disease to even more humans. Pennsylvania already leads the nation in the number of Lyme disease cases per year. This new, acorn powered mouse system, though, might drive our old infection numbers into even more astronomical levels!

So, oaks go boom and bust with their acorns and by feeding so many mammals and birds get the benefit of seed transport and dispersion! A couple of my young oaks actually made some acorns this past year! I wonder where they will end up?

 

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Signs of Winter 10: Delicious Microbial Ecosystems

Photo by J. Hamilton

I have to admit something: I love bread. I think that I could give up almost any other food more easily than bread. The very thought of not having bread (for breakfast, lunch and/or dinner) makes the meals feel incomplete and inadequate.

I have kept up with the growing nutritional literature that clearly shows that calories from carbohydrates (all those sugars!) are more likely to contribute to fat deposition (insulin is the mediator of this reaction!). Much of the blame for our obesity epidemic seems to be attributable to excessive carbohydrate ingestion. I do try to limit my sugar consumption from soft drinks (I avoid them), candy and cookies (I try to be disciplined) and prepared foods (is corn syrup in everything?), but bread, really good bread, and especially homemade bread, is something that I will not give up easily.

Both of my kids agree with me (only Deborah has any restraint on bread consumption in our immediate family!). Marian and Joe gave me a bread maker for Christmas, in fact, and I have been working my way through my bread cookbook making Challah, honey bread, Vienna bread, Swiss egg bread, whole wheat bread, and more several times a week. What an amazing invention! I wish that they would come up with a comparable “beer machine” so that I could as easily add homemade ale to my regular diet.

No, come to think of it, it is probably better that beer making is as time consuming and laborious (all of that washing and sanitizing!) as it is.

As part of our new, family bread making tradition, Marian bought three packages of sourdough starter from a company based in San Francisco and gave Joe and I each one for Christmas (and kept one for herself). We decided to each start our sourdough cultures at the same time in our respective corners of America (Seattle, Albuquerque, and Apollo, PA) and then compare the breads that we eventually make.

Photo by M. Hamilton

We all began our starters (which we will call our “sponges” from now on) within a few days of each other. Joe (in Seattle) and I (in Apollo) had an immediate problem with temperature. The mixture of water, bread flour and the provided packet of dried yeast and bacteria spores had to be incubated at 85 degrees! There was nowhere in Joe’s apartment or in our house that was 85 degrees this time of year! The packet instructions, though, suggested that you turn on your oven light and put the sponge container into the closed oven. Joe tried it and I followed suit, and it works!! We’ll figure out how to replace a worn out oven light later (I hope that it is not too expensive!)! All of our sponges, though, were happily bubbling away and giving off whiffs of alcohol and sour yeast. The sourdough, microbial ecosystem was established.

So what all was going on here? Why did we have to “feed” the fermenting brew every day for a week or more? Why was the texture and consistency of the sponge changing so much? What the heck was in that little dry pack of starter?

To answer these questions in reverse: the packet contained up to seven species of wild yeast and up to five species of lactobacilli bacteria (the classic sourdough microbial array!). These yeasts and bacteria have been identified as the “sourdough agents” responsible for the distinctive San Francisco sourdough bread! The yeasts (which are, of course, unicellular fungi that are able to live in both aerobic and anaerobic environments) first break down starches in the flour to mixtures of simple sugars and disaccharides (like sucrose and maltose) and then start to work on the simple sugars and the sucrose making lots of carbon dioxide in the process (all that bubbling!). The bacteria then start working in particular on the maltose (yeast are apparently “maltose intolerant”) and break it down to lactic acid and acetic acid (significantly dropping the pH of the system!) and the process make more carbon dioxide. There are hints of other organic acids in the scent coming off the sponge (not always pleasant odors!), but these scents change and mellow as the days go by (less butyric acid and more acetic acid, I am sure!).

There is an intense battle for space and food resources between the starter yeast and bacteria species and the yeasts and bacteria that were just riding along in the flour (or had just dropped into the system from the surrounding air!). Different locations will make different microbial contributions to the sponge (hence the Hamilton experiment across the country!). The starches of the flour are being rapidly broken down (which explains the sudden liquefaction of the sponge), and this food source needs to be replenished daily (hence the daily “feeding” of the sponge with fresh flour and water). The liquid portion of the sponge, by the way, is called “hooch” (that seems appropriate based on its smell).

Photo by M. Hamilton

The yeasts and the bacteria populations swing wildly up and down, but, eventually, reach an equilibrium and form a relatively stable community. All of this takes an active week or so of feeding and fussing (all at 85 degrees F!), and, then, finally, the sponge is ready to use in bread!

When making bread the added sourdough sponge yeast and bacteria will break down some of the starches in the bread flour and produce the carbon dioxide that acts as the leavening agent to make the bread rise! The sponge will also contribute many of the acids and other exotic flavors from its complex microbial community to give the sourdough its unique flavor. Often regular bread yeast is added to the mix just to make sure that sufficient carbon dioxide of produced to make the brad light and fluffy. Too much added yeast, though, can breakdown the flavors of the sourdough sponge.

I have made two loaves of sourdough bread so far. The complex sourdough flavors were only faintly detectable in the first loaf but much more robust in the second. The texture of both loaves, though, was incredible!

Lactobacilli bacteria like the ones in sourdough are also the major microbial agent in making yogurt! A particular species (Lactobacillus bulgarius (also called “Lactobacillus acidophilis”)) mixed with Streptococcus thermophiles break down the lactose (a disaccharide) in milk generating lactic acid in the process. These acids then denature the milk proteins causing curdling (thickening) of the milk (thus forming yogurt!). The breakdown of the lactose makes the food easier to digest and the acidic environment prevents other bacteria from growing in the yogurt (thus preserving it!). Another great use of bacteria!

I am going to have a slice of bread and some yogurt for breakfast! Go microbial ecology!

 

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Signs of Winter 9: More Birds!

Photo by D. Sillman

Photo by D. Sillman

We are coming up on a very exciting, four-day weekend! (Come to think of it: what four-day weekend is not exciting?) From Friday, February 17 to Monday, February 20, birders and bird enthusiasts from over 130 countries will be participating in the Great Backyard Bird Count (GBBC). The count is sponsored by the Cornell Laboratory of Ornithology, the National Audubon Society and Bird Studies Canada and is intended to be a “citizen scientist” assessment of bird populations from all over the world. Last year 162,052 check lists were submitted by participating counters, 5689 species were identified, and a total of 18,637,974 birds were counted. Pennsylvania had 8705 checklists submitted (second only to California among the U.S. states!), and several regular readers of this blog finished high on the list rankings of both Allegheny and Armstrong Counties! Check out the web site (http://gbbc.birdcount.org/) to see more!

Photo by D. Sillman

Photo by D. Sillman

This world wide count of birds began in 1998, and it 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!

The 2016 GBBC generated some interesting observations:

  1. Three Mexican and Central American thrushes (relatives of our very familiar American robin), the white-throated thrush, the rufous-backed robin, and the clay-colored thrush, were counted along with several other Central American bird species up in the continental United States. The speculation is that these birds are moving northward in response to the warming trend generated by climate change.
  2. Common redpolls (a northern finch species) were seen in regions far to the south both in 2015 and in 2016. The areas of their occurrence, though, were quite different. In 2015, the redpolls were primarily seen in the northeastern states of the U.S., while in 2016 they were seen in the northwestern states of the U.S. The reason for this shift from eastern to more western sites is not clear.
  3. Snowy owls continue to range southward all across the continental U.S. Increased summer prey in their arctic summer ranges (due to warmer temperatures?) apparently has caused a population explosion in this extreme northern species. In the winter, when prey is scarce, many snowy owls (especially young individuals?) have to make long southerly migrations in order to find food and avoid intense, intra-specific competition.
  4. The redwing (a European relative of the American robin) was seen in Nova Scotia and British Columbia. The British Columbian bird was thought to have been pushed over to Canada from Siberia by strong, El Nino powered winds! Another reflection in the GBBC of the impact of climate fluctuations on bird populations!
Photo by D, Daniels Wikimedia Commons

Photo by D, Daniels Wikimedia Commons

Also, the pine siskins which were seen abundantly in 2015 checklists throughout the northern U.S. were only rarely seen in 2016. Possibly the reduced intensity of the 2016 winter allowed these very northern birds to remain in their preferred northern, coniferous habitats.

So what is accomplished by this Great Backyard Bird Count? Tracking the pine siskins is interesting. Tracking the southward eruption of the snowy owls is exciting (check out the website!), and just knowing how many birds are out in our wide ranging habitats is important. But, maybe most important is getting all of these people outside all at once to look at birds! That is the payoff that is priceless!

Photo by D. Sillman

Photo by D. Sillman

The species that I counted for my 2016 Great Backyard Bird Count lists were as common as could be and included all of the top ten “most frequently listed” species from the study. I saw dark-eyed juncos (reported on 63, 110 checklists), northern cardinals (on 62,323 lists), mourning doves (on 49,630 lists), downy woodpeckers (on 47,393 lists), blue jays (on 45,383 lists), American goldfinches (on 43,204 lists), house finches (on 41,667 lists), tufted titmice (on38,130 lists), black-capped chickadees (on 37,923 lists) and the American crow (on 37,277 lists). My birding experience does not range into wild, exotic discoveries. I was very happy to see my cardinals, juncos, blue jays, titmice, chickadees, and crows!

Some years ago I was giving a talk at a conference about Deborah’s and my Virtual Nature Trail and the actual, physical nature trail on our campus that was the inspiration for it. At the end of my presentation I was asked a question, “what is special, or unique about this nature trail?” I sensed an undertone to the question of “why would anyone want to go see this trail?” Usually you come up with answers to questions like this much later, but somehow I found the answer right away: There is nothing particularly unique or “special” about this trail, and this is what made it so important. It is the beauty in the ordinary, as Bill Bryson once put it “the low level ecstasy” of the common species and common terrain that make this site so wonderful. Sitting back and seeing what is around you in nature always elevates and inspires you!

And, to me, this is what makes the Great Backyard Bird Count and the sight of all of those ordinary birds that every day gobble down my sunflower seeds, corn, peanuts and thistle, so amazing.

Photo by D. Sillman

Photo by D. Sillman

Another very interesting idea about birds and bird species was described late last year in a paper published in the journal PLOS ONE (November 23, 2016). Ornithologists at the American Museum of Natural History looked at the morphological and genetic characteristics of a sampling of bird species and determined that conventional methods of defining avian species were greatly underestimating the total number of species! Instead of the currently accepted 9000 or so species of birds, this group proposes that there are, in fact, 18,000 bird species. They came to this conclusion by utilizing an evolutionary species concept rather than the currently applied biological (or ecological) species concept. The evolutionary concept of a species describes distinct lineages of gene flow rather than the ecological occurrence of an interbreeding (or potentially interbreeding) population. One of the co-authors on this paper referred to the biological concept of a species (a traditional definition in most biological educations!) as “an outdated point of view.”

I am happy to be outdated on this subject as long as we can keep talking about birds!

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Signs of Winter 8: House Cat Day #5!

Taz and Friend Photo by D. Sillman

Taz and Friend
Photo by D. Sillman

Four years ago I wrote about Groundhog Day and suggested that we change this early February day-of-prediction to focus not on an animal that is sound asleep in his grass-lined burrow dreaming of gardens to ravage, but rather on an animal with whom we could more naturally base an ecologically or culturally significant day of hope for the coming spring.

I went through the cases for using a number of different species for our new holiday. Robins, for example, are the classical spring arrival species. Also, many robin flocks spend the winter locally in close by refuges. In fact, a flock of robins just dropped into my yard two weeks ago (January 5). They explored the leaf piles while snow accumulated on their heads and backs! Then they departed and I have not seen them since. With their sudden appearances and departures, robins might not be a reliable enough species on which to base our new holiday.

Photo by P. Vivero, Wikimedia Commons

Photo by P. Vivero, Wikimedia Commons

I also suggested bumblebees as an excellent indicator species in recognition of the early emergence of the hibernating queens and their remarkable ability to generate body heat and survive (usually) that initial cold flight of early spring. If we force the queen bumblebees out on early February flights, though, they probably would all freeze to death. Not a very happy thought for a day of celebration!

I also thought about scarlet tanagers as a species representing the long distance migrators that return to our northern habitats after a winter respite in South America. The scarlet tanagers, though, will not be around until April (much too late to get any publicity about the coming spring).

Taking all of this into consideration, I settled on what was, to me anyway, the most logical and most reliable and most available indicator species among us. That species, of course, is the house cat (Felis catus). Our cat, Mazie, is pictured below.

Photo by D. Sillman

Photo by D. Sillman

Cats are the most popular house pet in the United States (the Humane Society estimates that there 74 to 86 million house cats in the U.S. (as compared to “only” 70 to 78 million dogs)). As I wrote in my November 24, 2016 blog (“Our Other Best Friend”) cats have a complex relationship with humans and may be the only animal species that has chosen us as a co-evolutionary partner rather than vice-versa (hence the hypothesis that cats are not really domesticated at all but are wild animals exploiting our habitats and resources!). The resemblance of domesticated cats to their closely related wild species, the focus of many cats on places rather than people, and their perceived aloofness and self-absorption are factors that cause people to have intense feelings (both positive and negative) about cats.

A cat’s inherent love of sunshine and warmth, though, make them a perfect biological agent to help us predict the nearness of the coming warm seasons! And, since they are living in our houses year round, they are available for predictive experimentation!

Photo by D. Sillman

Photo by D. Sillman

Four years ago on February 2, 2013 I took Mazie out into the snow-covered front yard (I tried to take both of my cats, but Taz sensed that something was up and disappeared into one of her magical hiding places somewhere in the house). I put Mazie down in the yard (on a nice dry towel!), and left the front porch door open. If Mazie ran for the porch, then we would have six more weeks of winter. If she stayed on her towel or started walking around in the yard thus avoiding a dash back into the house, then spring was just around the corner.

I was amazed how fast she ran back into the house! But, that year the weather suddenly turned warm by late February. March temperatures set record breaking highs (I even remember a day when it nearly got up to ninety degrees!).  Maybe our predictive model was not articulated correctly.

In 2014 and 2015 I followed the same experimental procedure, and Mazie, as I reported on this blog, responded with equal speed and agility and got back into the house almost before Deborah could take the lens cap off of her camera. In both of these years winter hung on grimly well into March. Mazie’s predictions, then, fit the observed phenomenon.

In 2016, though, Mazie’s response to the front yard was entirely different. She stepped off her towel and explored the front flowerbed, jumped at some little Pardosa spiders that were running around in the grass and seemed to enjoy herself very much. The early onset of spring that this behavior predicted came about! We had a mild, pleasant March and April and eased our way into a warm early summer.  Mazie had delivered in three out four years! She should get a job with The Weather Channel!

We’ll find out on Thursday, February 2 if Mazie’s weather predictive abilities continue to prevail!! She will return to the front yard for our fifth experimental trial. Deborah will have her camera all ready to record the action! I am sure that Mazie will do her best for us all!

Photo by M. Hamilton

Photo by M. Hamilton

By the way, my daughter who lives in Albuquerque also plans to put her cats (Mora and Bella) out on House Cat Day (Mora and and the much missed Binx are pictured to the left). The predictive model is slightly altered down there in warm, sunny New Mexico, though. When her cats go outside into the southwestern sunshine they typically do not come back into the house until it is time for dinner. In early February, the New Mexico spring has already started! In order to make House Cat Day a worldwide event, we may need to adjust the timing model in order to compensate for variations in latitude.

Send on your own experiences and observations!

Happy Winter, everyone! (But, it’s almost time to start thinking about Spring!)

(House Cat Day 2017 is once again dedicated to Taz and Binx. They will be greatly missed forever!)

 

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Signs of Winter 7: Communities, Organisms and Science

Photo by D. Sillman

Photo by D. Sillman

An ecological “community” is the sum of all of the populations (i.e. all of the groupings of each species) living in an ecosystem. When you stand in the middle of an ecosystem you can see many of its species and can even appreciate their interactions and interconnections. There are, however, many organisms that evade casual observation and many kinds of important interactions that pass unnoticed.

The ecosystems here in Western Pennsylvania in which Deborah and I have spent most of our time have ecological communities that are somewhere in the middle of the worldwide continuum of complexity. They are not the bare bones systems of desert islands like we have seen in the Galapagos, nor are they the dense, almost incomprehensible species rich riots of tropical rain forests or coral reefs. Here there is almost but not quite too much to see in a given community, but there is also the luxury of finding new species or recognizing new interconnections whenever you return to a place or whenever you start to look at it in a slightly new way.

A wonderful T. S. Eliot quote comes to mind: “We shall not cease from exploration, and the end of all our exploring will be to arrive where we started and know the place for the first time.”

But what exactly is this thing we call a “community?”

Photo by D. Sillman

Photo by D. Sillman

Back in the early decades of the Twentieth Century there was a lively debate among scientists who were working in the brand new scientific discipline that they called “ecology.” One group led by Frederick Clements described plant communities (associations of plant species occurring together) as distinct and identifiable entities. Clements felt that each species contributed to the community in certain ways and every other species relied on and depended upon the other species in the community. There was a meshing, a synthesis, events full of emergent properties out of which the community became more than the sum of its parts. Clements extended these ideas to then describe how communities change over time (the process of “ecological succession”), and he described the patterns and the steps and the stages of these changes and maintained that ALL plant communities changed in this linear way and that ultimately ALL plant communities developed into stable, “climax” communities.

Clements first relied on a simile when he described his plant communities: these communities were “like” an organism. But, as my first ecology professor back at the University of Texas  put it (and he had known Clements personally), he then began to describe a plant communities as actually being organisms! The level of integration and interaction in a community was likened to the homeostatic events that enable the trillions of individual cells in each one of us to function as a distinct, singular being.

Photo by D. Sillman

Photo by D. Sillman

Now many felt that Clements had gone too far. They felt that his “community as an organism” hypothesis strayed away from science and plunged headlong into mysticism and theology. Henry Gleason was one of the most vocal opponents of Clements’ “community as an organism” idea. Gleason described plant communities as associations made up of independently striving species. He stressed that no two plant communities were exactly the same. Gleason’s ideas at first prevailed, but there is something compelling and attractive, something emotionally appealing to Clements’ more holistic framework, and his ideas regularly resurface in the developing theories of ecology.

Are we living parts of some greater organism? Are all the populations of plants and animals and bacteria and fungi around us functioning as tissues and organs in this great beast of the Earth’s biosphere? If this is science we should be able to come up with some predictions for the outcomes of a set of experiments that should occur of the hypothesis is accurate, and if these predictions don’t occur, we should reject the hypothesis. Scientific speculations are always falsifiable, after all, and many good ideas end up in the trash can of our laboratories.

If this isn’t science, though, then we don’t really have to check the ideas beyond their emotional feels and fits. Does it “feel” right to think of the Earth’s biosphere as an integrated organism? Does that idea (or “belief”) improve your quality of life? Does it make you less anxious or more confident of your place and purpose? If so, then it is quite possibly a start of a philosophy or even a theology.

Photo by D. Sillman

Photo by D. Sillman

It is really important, though, to recognize if we are talking about science or about theology, and it is really easy to let the lines blur between them. I agree with Alice Dreger (“Galileo’s Middle Finger”) that science is not just “another way of knowing” that is comparable with any other theological or philosophical system.  Science is a system not of belief (as Adam Gopnik recently asserted in a book review in the “New Yorker”) but of challenges. Science is a system that harnesses the inherent creativity of the human mind and demands slow, hard work to show that a good idea or explanation is truly possible or supportable (note that I don’t use the word “true.” Truth is too high a bar for science to attain. Truth implies an end point, and science always keeps the possibility alive that if just a little bit more information is gathered, just a slightly different perspective is developed, a scientific explanation could be completely upended).

Science has frequently been perverted by authoritarianism and autocratic declarations, it has been frequently hijacked by strong personalities and clever arguments, and it has been corrupted by dishonest researchers, but it is a system that eventually self-corrects and throws out these short cuts and partial ideas. Science’s history is one of many small steps forward, and occasional wild lurches both backwards and sideways.

So, is an ecological community a living organism or is it “like” a living organism? The line between the two ideas is very thin and very tortuously curved. I find myself jumping back and forth like the twins on the old Certs commercials: “it’s a candy! “It’s a breath mint!” “It’s an organism!” “It’s a complex, homeostatic system with a wide range of emergent properties!”

Science almost always needs more words that will fit on a bumper sticker!

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Signs of Winter 6: One Hundred Words for Snow!

(some information in this post was published in a January 23, 2014 blog)

Photo by E. S. Curtis, Wikimedia Commons

Photo by E. S. Curtis, Wikimedia Commons

Frank Boas was an anthropologist who studied and lived with the Inuit people of northern Canada in the late Nineteenth Century. He is credited (or, sometimes, blamed) for observing that the Inuits have a hundred, words for snow. His logical explanation was that dominating or important components of a culture’s environment must be reflected in the diversity of their language about those factors. And, Inuits are absolutely surrounded by snow!

I don’t know if Inuits really have that many words for snow. I also don’t know if temperate climate dwelling people, as has been alleged, have at least as many words for liquid water (think pond, lake, river, creek, rill, run, puddle, etc). I am convinced, though, that anyone who likes to ski knows quite a number of combinations of adjectives and nouns for their much beloved sliding medium and, most importantly, I am convinced that despite obvious personal inconveniences and driving difficulties, winter is greatly improved when there is snow!

Photo by A. Kljatov, Wikimedia Commons

Photo by A. Kljatov, Wikimedia Commons

Snowflakes form in very cold clouds when a starting “nucleus” (which could be a few water molecules that have randomly formed a small crystal, or a suspended clay or dust particle, or even a pollen grain) collides with a very cold water droplet. This water droplet freezes on contact with the “nucleus” and forms an ice crystal. These crystals then adhere to more water molecules in the cloud to form the larger and larger crystals which eventually become snowflakes. Once these snowflakes reach a certain size they begin to fall down through the atmosphere and can add, depending on the water content of the air masses they are falling through, more and more water molecules to their expanding crystals.

snowtypes4.jpgThe temperature and water content of the clouds and the underlying air determine the eventual size and shape of resulting snowflakes. Two snowflakes forming under identical conditions would, in spite of the old truism, be expected to be identical. The variability of conditions in any given cloud and in the surrounding air masses, though, makes forming identical snowflakes very unlikely. Kenneth Libbrecht at Caltech identifies thirty-five different types of snowflakes (great thanks to Kenneth for allowing the reprinting of his snowflake chart (from snowcyrstals.com)). Each type of snowflake is sculpted by the specific environment in which it originates.

Once on the ground the snowflakes accumulate and weather into a great variety of secondary shapes. There is powder snow (freshly fallen often low moisture snow that has not been compacted), crust snow (hard packed snow often iced together by rain), corn snow (lumpy snow made by freeze and thaw cycles), firn snow (old snow (more than a year old) that is granular but not excessively compacted), slush snow (partially melted snow often with puddles), snirt snow (snow covered with dirt and debris), watermelon snow (red colored snow due to the growth of an algae species), Yukimarimo snow (little balls of frost (seen in Antarctica), and more (maybe a hundred different kinds?)! Snowflakes can even (if they build up deeply enough and persist for long enough) compress themselves into massive systems of glacial ice.

Photo by J. Cotton, Flickr

Photo by J. Cotton, Flickr

The snow can also interact with the soil and surface litter and vegetation on which it falls to form a very interesting interface called the “subnivian space.”  The subnivia is a thin air layer found between the covering snow and the soil surface. It forms especially well when the snow layer becomes established prior to the hard freezing of the soil, and it is especially well established in complexly structured, “natural” soil-litter systems (as opposed to lawns or barren fields). Falling snow gathers on the surfaces of the irregular profile of the leaf litter and forms complex arches and domes over the dead plant materials. Heat from the unfrozen soil and also from the decomposition of the organic molecules in the leaf litter melts the contact snow layer which quickly re-freezes to form thin ice sheets which add to the structural strength and also to the insulating potential of the forming snow pack. A winter with a continuous snow cover will allow a significant and continuous subnivian space to form.

Photo by D. Sillman

Photo by D. Sillman

Within this space (which may be several millimeters to even a couple of centimeters thick) a great variety of living organisms can be found. The micro-climate of the subnivia is sufficiently mild to allow temperature sensitive invertebrates (like beetles, collembola, mites and spiders) to continue their ecological activities of decomposition and predation throughout the winter season. Many small mammals (like voles, shrews and white footed mice) use the insulated subnivian space as shelter against the harsh surface conditions and also as a safe conduit between forage sites and their burrows. Within the subnivian space they are hidden from surface dwelling mammalian and avian predators like red foxes and hawks and owls. These predators can be observed in the winter standing very still on or just above the snow surface using their keen senses of hearing rather than vision to detect these subnivian mammals. Track histories of red foxes in particular reflect the slow, quiet stalking, pausing, and explosive digging through the snow cover as the foxes’ search for their subnivian prey.

It is a rare year that we have a continuous and appreciable enough snow cover to allow the formation of a true subnivia here in the lowlands of Western Pennsylvania. I have seen, though, vole tracks worn in the grass of my front yard converging onto the seed spill area under my bird feeders after our transient snows melt. The voles use the insulating and protective cover of even a few inches of snow to help themselves, like every other species around here, to my dearly purchased black oil sunflower seeds! I hope that they get some of the corn, too!

 

 

 

 

 

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Signs of Winter 5: Remembering a Summer Hike (part 2)

Photo by D. Sillman

Photo by D. Sillman

We return to our parking spot the next day and keep on our return arc back toward Freeport Road. The yellow blazes for the trail are fresh and numerous and  lead us across the lower park road and down a narrow, muddy trail that rises up into a clearing ringed with berry-laden Tartarian honeysuckle bushes. Tartarian honeysuckle is an exotic invasive but its red and orange berries are edible and may be providing some birds with an energy-rich food source.  We cross Freeport Road with little difficulty and turn left down Altermoor Road walking past house after house with their acres of tended lawns.

Photo by D. Sillman

Photo by D. Sillman

After a block and half or so Altermoor Road turns to the north, and there is a double yellow blaze with the top mark off-set to the left indicating that the trail turns left at an old gas line sign. We follow the trail on into the woods and quickly leave the neighborhood behind. The trail is muddy and densely lined with an odd collection of herbaceous plants (which included white avens, burdock, wing stem, blackberries, black raspberries, jewel weed and enchanter’s nightshade). It is like the old field plants from the road edges and fence rows around the neighborhood have oozed their way through the opening of the trail down into the surrounding young woods. Trees are primarily black cherry, white ash and hickory. The trees get larger as we move along the trail and soon, especially when the trail rises up a few feet and becomes substantially less damp, red oak and chestnut oak become more abundant. With the appearance of the oaks, the density of the surrounding vegetation drops off greatly.

Tufted titmice and chickadees buzz over the trail and forage for insects up and down the tree branches. The black cherry trees have abundant, mostly green fruit that is just starting to show some early signs of ripening. A flock of cedar waxwings noisily flutters around the cherry branches and pecks at the, probably, still hard cherries. I have heard that the unripe black cherries are eagerly consumed by many birds and squirrels, and the waxwings seemed to be getting more than their share of this early harvest. I remember reading once about a species of baboon in Africa who were able to digest unripe, green figs. These baboons could swoop into pre-ripened fig trees and clean them out before any competitor (who could only digest the ripe figs) had a chance to get to the fruit. These baboons, according to my sketchy memory, produced powerful polysaccharide digesting enzymes which enabled them to break down the very resistant structural polysaccharides of the green figs. I wonder if the waxwings had similar digestive adaptations that enable them to get such a start of the unripe cherries? It would be a great selective advantage!

The trail takes a downward turn and suddenly becomes wet and muddy once again. The surrounding vegetation has a marshy appearance (skunk cabbage and sedges) and is enveloped in dense patches of multiflora rose. We cross a flowing creek and then head back up the trail. Slowly the ground dries once again.

Photo by D. Sillman

Photo by D. Sillman

Bright orange mushrooms are sprouting from the standing tree trunks, some of the downed wood, and, apparently, from the moist, black ground itself! A number of the black cherry trees have woodpecker holes carved into them. The size and depth of the holes (and the exuberant numbers of them) suggest that they have been made by pileated woodpeckers. Many of these holes would be perfect for cavity-nesting bird species (like bluebirds or tree swallows) to use for their nesting sites. It has been said that anything one does to increase woodpeckers in an ecosystem will also increase bluebirds!

We cross through a gate and enter what is labeled on the trail guide as the “Corral.” Signs caution every one hiking through this section to remember to secure the gates and to refrain from approaching any horses you might encounter. We saw no horses (sadly) and no fresh sign of any horses either. We are very thankful, though, that the owner of this large horse pasture allows hikers to freely cross their property!

Photo by D. Sillman

Photo by D. Sillman

We walk along the rolling pasture trail. Low spots are wet and muddy, and high spots are dry and firm. We cross through several sections of dense woods and see several exit gates uphill off to our left. Our path, though, keeps to the pasture. At once point we break out of a dense, still wooded area into a breezy, open old field. It is good to feel the cool breeze on this warm and increasingly humid day! The old field is rich with plant species. Yarrow, ox-eye daisies, bird’s foot trefoil, curly leafed dock, heal-all, and more fill up the horizontal and vertical spaces of the field.

Some chimney swifts fly overhead, chattering away gobbling up some of the mosquitoes that have been swarming around us (I hope!).

A warbler darts in and out of the dense branches of the thicket along the left side of the trail. I see flashes of yellow on its head, a black throat and chest, and dark sides with white stripes. I write down the field markings and then look it up in the field guide later: it is a black-throated, green warbler! Not especially uncommon, but a first for me! He sings a buzzy, staccato song that falls then rises into a definite “dee” ending. Great bird!

Photo by D. Sillman

Photo by D. Sillman

We leave the woods and walk past a family setting up for a cookout in their backyard.  We follow their driveway down to Alter Road and turn to the left. Alter Road is very quiet, but it is narrow and winding with some scary blind curves. We stay alert and walk quickly so that no on-coming or passing cars can surprise us. We take Alter down to Saxonburg Road and walk in a narrow bike lane (it looked like a bike lane, anyway). Large trucks race past us. The heat and exhaust fumes from the passing vehicles makes me a little lightheaded. We cross under Route 28 and then are soon able to cross the road to reach a broad, gravel shoulder. Just putting a few steps between ourselves and the hot, fume-laden road is a great relief. We see a bike rider pushing off from a crossroad during a traffic lull. He smiles and waves as he glides past us.

We turn left on the road from which the bike had emerged (Donnelville Road) and then after about 100 yards turn left again onto a gated service road that climbs up to a cell phone tower (our next hiking goal!). We pause at the gate and sit down on a soil pile to have a gorp and water break.

Photo by D. Sillman

Photo by D. Sillman

The hike up the cell tower road is steep, long and hot. We have another drink of water at the top and then work our way around the tower and along the gas pipeline. Our path crisscrosses a power line right of way for the next couple of miles, and we go from the cool, but somewhat airless shade of the woods in and out into the breezy, but sunbaked sections of open old fields under and around the tall power lines.

There are large puddles everywhere up here on top of the long ridge. Some

Photo by D. Sillman

Photo by D. Sillman

puddles in are broad low spots generated by vagaries in the soil topography while others are in deeper ruts carved out by vehicles (and ATV’s) using the soft dirt and gravel access roads. There are small cluster of air bubbles floating on many of these puddles. Closer examination shows that the air bubbles are being utilized as refuges by a substantial number of predaceous diving beetles.

There is some ominous wording in the trail guide about the way this section of trail ends. It says: the trail “descends steeply and dramatically down to Burtner Road.” Now you have to know your trail guide author to know what “steeply” and “dramatically” really mean. Some authors are prone to be a bit hysterical and hyperbolic in their use of adjectives and adverbs while others are maddeningly understated in their descriptive vocabulary. We weren’t sure to which stereotype out trail guide author leaned. We know now, though: understated to the extreme.

I am looking at the topo map of this part of the trail. We had come to a significant downward trail section that is pretty steep but still very walkable. We then went down about 80 feet in a sixteenth of a mile and had to negotiate a deep erosion gully on our way down. Out on the trail, I was not sure if this is the described ending section of the trail or not, but feel that it was not too bad.

Photo by D. Sillman

Photo by D. Sillman

In about a half a mile, though, we hit the “drama.” We go down 140 feet in a tenth of a mile and then back up 80 feet in much less than a tenth of a mile. From our perch up on top of the ridge we see our next trail section (which causes us to consider changing our summer hiking plans) and hear a hint of the passing traffic on Burtner Road. We then go down over 200 feet in less than a tenth of a mile often sliding on our rear ends to keep from careening out of control down the slope. The ridge from which we start our potential energy dispersion is 300 feet above the elevation of the road. We had done all of the “down” over almost no linear distance.

We were very happy to get into the car! We also decide to do the rest of this trail some other year!

 

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Signs of Winter 4: Remembering a Summer Hike (part 1)

(I have been saving these next two posts for the winter. Let’s all enjoy the color green for a while!)

Photo by D. Sillman

Photo by D. Sillman

The Rachael Carson Trail starts as a straight uphill climb from Freeport Road on the north edge of Harrison Hills Park. We park across the street, dodge our way across four lanes of traffic, and then walk up the gravel road/driveway that winds up toward a large cell phone tower. The sign announcing the trail is relatively new and unweathered, and the narrow road (or broad driveway?) has only a few signs of damage from the recent heavy rains. The blazes for the trail are yellow, and they are also fresh looking and clearly positioned.

The trail follows three sides of a tall, chain link fence that surrounds the cell phone tower. Signs prohibiting trespassing are prominent all along the fence line. The fence is not electrified but looks as if it could be! We keep the fence to our left and a dense mass of ecotone vegetation (dominated by poison ivy) to our right.

Photo by D. Sillman

Photo by D. Sillman

The trail heads off to the right away from the tower and dips down into a muddy rut. You have to choose to either walk in the mud or brush against the edging vegetation. Again, poison ivy is the dominant species here along with raspberry, blackberry and multiflora rose, so avoiding the urishiol and the thorns seems like a good idea. Boots and socks get soggy quickly.

Very soon, though, we break out of the dense vegetation and climb up onto the dry, open oak forest that runs along the top of the cliffs on this west side of the Allegheny River. The river far below is chocolate brown from all of the recent rain and runoff. It is also running very high and fast. Signs along the trail caution everyone to watch the drop off! We are at eye level with the vultures that frequently soar along the river.

The path follows the contours of the ridge down into gullies that are bottomed with rocky streams and then back up again. The rocks are slippery with mud and silt, and swarms of gnats and (probably) mosquitoes hover over the water.

Photo by D. Sillman

Photo by D. Sillman

Mushrooms are everywhere! Orange and red and yellow and brown, small button shapes and larger “toadstool” shapes, cones and goblets, and great, free-form lumps of tissue. The incredibly wet past month has triggered all of the soil fungi to make their mushrooms all at once!

Indian pipes are up, too. Older pipes have opened up their tops in a flower-like profusion while the newer pipes still have their dangling tight shapes. We hiked along here a week ago and only saw young

Photo by D. Sillman

Photo by D. Sillman

pipes, now we mostly see the opened shapes.

We scare a deer up from a woody hiding spot down off the trail. She goes leaping off through the dense underbrush and disappears down a hollow in series of crashes and snapping branches.

The streams driving down the steep slope to the river have cut deeply into the underlying rock. They tumble in short waterfalls over larger rocks and zig-zag around the standing arrays of smaller ones. The rocks are swept clean of any soil or silt. They are being continuously polished by the flowing water.

Along the trail oak seedlings (mostly chestnut and white oaks) grow in profusion. They are a foot or two tall with apical clusters of huge leaves.

Photo by D. Sillman

Photo by D. Sillman

In places there is an inch or two of flowing water on the trail and we have to step out into and on the surrounding vegetation. We keep a close eye out for poison ivy but have to walk where we can. We cut across the large playground and parking area and re-enter the woods. We walk over the arching, wooden foot bridge and turn right to follow the yellow blazes. After a couple of dozen yards we come to a large, black cherry tree that has fallen across the trail.

The tree has fallen in the last week. We walked this section of the trail the previous Monday and had no impediments. The violent thunderstorms of the intervening weekend probably took it down. The tree is about two feet in diameter and extends far off the trail in both directions. So, there is no choice, we either go over it or turn back. We climbed up over the first part of the tree and get ready to slide down and crawl under the second part when we notice that not only is the tree trunk on which we are perched covered with poison ivy vines but that I am holding onto a “branch” for balance that it actually a woody extension of one of the intertwined poison ivy vines that encase the entire tree. There is nothing to do by go on and we crawl down off the first trunk and under the second.

Photo by D. Sillman

Photo by D. Sillman

There are three more black cherry trees down across the trail ahead and we climb and crawl over them trying to keep from touching our faces with our possibly urishiol covered hands. Deborah walks ahead and gets a covering of itchy spider webs across her face but leaves them there.

We have about a mile more to walk and after some more mud and slipping and sliding (and a downpour of unexpected rain) finally see the car in the parking area.

(UPDATE: neither Deborah nor I got any poison ivy from our above encounter, and I really can’t explain why! Next week: Part 2 of this hike!)

 

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Signs of Winter 3: More Winter Birds

Photo by D. Sillman

Photo by D. Sillman

(some of this information was first published in a January 15, 2014 blog)

Every morning right after taking Izzy for her walk and well before my first cup of coffee I go out to fill my front yard bird feeders. I cannot leave full feeders out at night because all of the seed would be consumed by my voracious herd of white-tailed deer. Each morning I put a large scoop of black-oil sunflower seeds into each of the hopper feeders (usually just enough for a day’s feeding) and throw a couple of handfuls of peanuts and a scoop of shelled corn on the ground beneath them. I usually have to fill the heated birdbath, too (the deer have also taken to drinking out of it at night!). As I walk back into the house I look up in the branches of the tall, black locust tree behind my house and usually see one or two crows watching for their opening to come down and eat the peanuts. They start cawing and bobbing their heads when we make eye contact, and often by the time I get back inside to get the coffee started they are in the front yard, hunched over the peanuts. Soon the gray squirrels arrive to scoop up the corn and do their early morning acrobatics in sunflower seed feeders. Some mornings they even get a few peanuts that the crows have overlooked. The ground is cleared very quickly and then the feeder birds begin to arrive.

Photo by D. Sillman

Photo by D. Sillman

I want to have the feeders full first thing in the morning because the birds have had a long, cold night of intense metabolic heat generation and are in desperate need of re-fueling. Different species come into the feeders in distinct groups although their timings of arrival vary from day to day. Often the cardinals are the first to come in for their breakfast followed by the chickadees and titmice. Blue jays then push their way into the feeder perches and noisily drop down to the ground to take any nuts or corn that have been left behind. Juncos, mourning doves, white- throated, white capped and song sparrows peck around on the ground at the seed spilled from the hanging feeders, and finally the house finches swarm in and feed. Then there is usually a pause and the groups cycle back in all over again.

Photo by K.C.Agar, Flickr

Photo by K.C.Agar, Flickr

Occasionally, downy woodpeckers, red-bellied woodpeckers and northern flickers come into the feeders (and to the suet cakes if I remember to put them out). Our two Carolina wrens (who amazingly sing all winter!) also come into the feeders in between the larger, single species groups along with the white breasted and the rose breasted nuthatches. Every once and awhile some different species, often just a single individual, drops in for a snack, sticks around for a day or two, and then disappears from the yard. A few winters ago a wood thrush stayed around for several weeks. He used his long, insect grabbing bill to crack open sunflower seeds! Last year a golden-crowned kinglet showed up for Christmas (he kept to the surrounding arbor vitae bushes gleaning up and down the branches for insect larvae), and every once and a while a stray robin stops by (usually looking quite cold and confused).

Photo by A. Wolf, Wikimedia Commons

Photo by A. Wolf, Wikimedia Commons

One very interesting behavior that can be observed in the many of the winter birds away from the bounty of the yard feeders is the formation of mixed species flocks. The chickadees, titmice and downy woodpeckers in particular join together into large, complex flocks for the winter. At first glance this flocking behavior would seem to be disadvantageous to all of the species and to all of the individuals concerned. Food is in short supply in the winter, so how could the clustering of many individuals that all eat approximately the same prey items (primarily insect larvae) do anything but decrease the survival of respective species? The answer involves the facilitation of food finding and the reduction in the average individual’s energy devoted to searching for food. In the large mixed flock there is a very high probability that some flock member will find a food source (a cache of larvae under some tree bark for example). Exploitation of food sources by the entire flock with the subsequent high probability that another individual will soon find another food cache “smooths out” the boom and bust food cycle of the winter system, and thus increases the survival of a higher percentage of individuals in the mixed flock. Further, from the perspective of the downy woodpecker, flocking with the very alert and excitable chickadees and titmice also increases their awareness of incoming predators and thus adds to their chances of winter survival.

Another interesting natural behavior that was described by Aldo Leopold (author of the “Sand County Almanac”) is the positive response of chickadees to loud, explosive noises (like shot gun blasts or tree limb breaks). The chickadees swarm toward the sound very energetically (and in a mixed flock carry along the titmice and downy woodpeckers with them).  The breaking of a tree limb or the falling of a tree opens up the woody encasement that may be full of ants, ant larvae or other insect larvae. Drawn to the loud noises, these birds can rapidly exploit a suddenly available food source.

Photo by D. Sillman

Photo by D. Sillman

The main predator that regularly shows up at our yard feeders is the sharp-shinned hawk. The small, male and the larger female sharp-shins swoop across our yard at least once a week. Their success rate at securing their prey is not great, but once a month or so I find a pile of plucked feathers (usually from a dove or a cardinal) under one of their perches along the wooded edges of my field. Soon the female sharp-shin will start her mating calls (an event that Deborah videoed two years ago). I haven’t seen any immature sharp-shins around the yard or field, though, so it seems that their winter, mating “dance” has not been productive.

Photo by D. Sillman

Photo by D. Sillman

Bird songs are one of the most beautiful aspects of nature. Theories have been proposed that the first music made by humans was an attempt to recreate and control the haunting beauty of these natural songs. The fields and woods do seem empty in the winter without the whistles and melodies of our songbirds. We do hear the buzzing of the chickadees, and the rapping of the woodpeckers, the raspy whistles of the white-throated sparrows, and the occasional, rolling trills of the Carolina wrens, but the lack of full chorus singing makes the yards and the woodlots seem empty and barren.

Why don’t most of the birds sing in the winter? The answer lies in the reason for bird songs in the first place. Although many birds do use song as a mechanism of individual recognition and contact, the primary reason for song is advertisement of themselves! The male bird sings to declare his vigor, his individual territory and to attract a mate (or as many mates as possible depending on the species!). Mating is not one of the biological functions of the winter season, so most songs are left unsung until spring.

I guess that a better question might be, why do some birds sing in the winter anyway? I am going to ponder that one for a while.

 

 

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