Signs of Winter #4: Arrival of the Juncos!

Photo by Ken Thomas Wikimedia Commons

Photo by Ken Thomas Wikimedia Commons

When we think of bird migration we usually focus on those species that arrive here in the spring and then depart from here in the fall. These species are utilizing our rich, productive summers and avoiding our cold, food deprived winters. There is, though, a very interesting bird that arrives in our area in the mid- to late fall, thrives in our winters (often supported by our backyard bird feeders!), and then heads back into its northern breeding habitats in the spring. The bird is, of course, the northern junco.

I saw my first northern junco of the fall on October 30. He was poking around at the spilled sunflower seeds under my feeders and looked very much at home among the chickadees, titmice, cardinals and house finches.

The northern junco is small, dark-colored sparrow with a long list of very descriptive common names including “dark-eyed junco,” “slate-colored junco,” “snow bird,” and “winter finch.” The Northern Junco is a very common bird at almost any winter bird feeder throughout the United States. It over-winters in almost all of the lower forty-eight states (and down into northern Mexico) and has an equally broad summer/breeding range across Canada and Alaska. Breeding may also occur in the mountains of the west, throughout New England, and down the Appalachian Mountains into northern Georgia. In Pennsylvania, in addition to winter populations of “bird feeder” northern juncos, Deborah and I have observed dense, summer populations of this species in the mixed hardwood forests of the Allegheny National Forest in the northwest section of Pennsylvania.

The northern junco is five to six and a half inches long and weighs between one half and nine tenths of an ounce. Males are slightly larger than females and are more darkly colored. They have gray hoods and backs, white bellies, and dark tails with distinctive white, lateral tail feathers. They also have short, triangular beaks and dark eyes. Juveniles are brown in color and have finely streaked, white breasts.

Photo by Mdf Wikimedia Commons

Photo by Mdf Wikimedia Commons

Like most sparrows, the northern junco will eat a wide variety of foods. Their beaks are especially well adapted to cracking open even tough seeds (including sunflower seeds at bird feeders and an extensive number of wild plant (“weed”) seeds in their natural habitats). They also readily consume fruit (including wild blue berries, raspberries, and elderberries as they come into season) and many types of arthropods (including caterpillars, ants, flies, spiders, and beetles). They typically feed on the ground and move about both by walking and by hopping (a single hop can cover thirty centimeters). Natural ranges can be quite extensive (a single flock of juncos can feed in an area of ten to twelve acres), while human-modifications of their feeding ranges (i.e. bird feeding stations) can greatly reduce the size of the foraging range and overall rate of movement.

Flocks of fifteen to twenty individuals form in the autumn and winter. These flocks may include several of the sub-species of the northern junco and also several other species of sparrows and even bluebirds. These flocks gather together about thirty minutes before sunrise and disperse about forty-five minutes before sunset each day. Foraging success for each individual is significantly increased when they participate in one of the groups. An individual junco tends to stay in its foraging flock for the entire winter.

Males move into their summer breeding habitats in northern coniferous or mixed hardwood forests before females and mark off their individual breeding territories. A male will sing from the top of a tall tree to claim an area of two to three acres. They then attract the attention of the arriving females by dropping their wings and flaring their tails in order to show off their white, lateral tail feathers. Once a female accepts a male they become quite inseparable and within their territory seldom venture more the fifty feet away from each other.

The female builds the nest all on her own. The nest can be located on the ground or on low, horizontally oriented tree branches. Near human habitations juncos may also build their nests in the crawl spaces underneath buildings, inside the buildings themselves or on window ledges. The nest may be made of a variety of materials. Sometimes it is simply a gathering of pine needles and grass, sometimes it has a foundation of sticks on top of which softer materials are layered. Nests take three to seven days to build and they are seldom re-used.

Northern juncos typically have two clutches of three to five eggs each breeding season although under optimal weather conditions, a third clutch is possible. The first clutch is laid in late spring (mid-April) and the second in mid-summer (mid-July). Eggs are incubated by the female for just under two weeks. Nestlings are actively fed by both parents and are able to fledge after another two weeks or so. Fledglings stay with and are dependent upon the parents for another three weeks. Males are very aggressively territorial during this reproductive period. Both male and female, though, will very vigorously defend their nest and nestlings.

The arrival of the juncos in Western Pennsylvania has both positive and negative implications: a handsome bird has returned to grace our lawns and fields, but now we have to deal with the cold, snowy months of winter!

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Signs of Winter #3: Ecological Premonitions

Photo by IronChris, Wikimedia Commons

Photo by IronChris, Wikimedia Commons

There are many amazing things about nature that are both observable and explainable. One that probably isn’t, though, involves organisms like oak trees and woodpeckers and spiders forecasting, many months ahead of time, the intensity of a coming winter. For this to be observable and explainable one would have to assume that these species (and many more for that matter) somehow perceive clues in the environment that we lumbering (but sentient) bipeds do not. Take the wooly bear caterpillar for example: it is alleged that they take on a darker color if the coming winter is going to be more severe. What would be the trigger for that color change? And, maybe even more significantly, why would they do that? Even if they could perceive some clues that the coming winter was going to be cold and snowy, what advantage would it be to the caterpillar (or to the overwintering pupa of that caterpillar, actually) to have an abundance of black body hairs? There would have to be some selective advantage or the character would never have evolved!

Ten years ago I had an ecology student who wanted to study wooly bear caterpillars. His idea was to collect as many wooly bears as possible and see if their “message” was consistent across the population. He collected one hundred wooly bears over a four week period and determined the size of their black bands. He found that their winter forecast was, at best, random. The early collections seemed to lean toward a mild winter (narrower black bands) and the later collections seemed to lean toward a more severe winter (broader black bands) but the variation in each collection almost completely obscured their overall trends.

We determined two things from this wooly bear study: 1. As wooly bear caterpillars age and grow, they develop more black hairs, and 2. Selective observation of the wooly bear population (only observing a very small number of individuals at any one time) could lead you to conclude whatever you might want about the coming winter.

Selective observation may be the operational idea here!

Photo by D. Sillman

Photo by D. Sillman

There are a number of winter-predictive observations that involve things happening “earlier” than usual. There is the “early” departure of geese and ducks, the “early” migration of the monarch butterflies, and the “early” hiving up of honey bees. The quality of these observations, of course, depends upon prior knowledge of exactly when these events have happened in the past and, therefore, should be happening in the present. This data is not readily accessible.

There are also a number of observations of things being more abundant or more developed than usual. An “excess” abundance of acorns, “thicker than usual” corn husks, “more abundant than usual” late summer frogs, “thicker hair than usual” on the back of a cow’s neck, more mice (or crickets) than “usual” entering your house, and “larger than usual” spider webs being spun out in the garden. Again, the data base of “normal” or “usual” for all of these events just does not, as far as I know, exist, but if you happen to see a large spider web, or happen to hear lots of mice in your kitchen, then you might easily jump to whatever conclusions you want and then feel the need to start stocking up on canned foods!

Squirrels are also used as winter-indicators. They “frantically” gather acorns in anticipation of a coming hard winter. I have never seen a squirrel gathering acorns (or chestnuts, or hickory nuts) in anything other than a “frantic” manner. A leisurely working squirrel is very likely to become a quick lunch for a red-tailed hawk!
There were a couple of nature’s “winter predictors” that might have some validity, though. The “early arrival of snowy owls” might be indicative of the early movement of cold, polar air masses down to lower latitudes. “Foggier than usual” August and a prevalence of autumnal halos around the moon might also indicate the early arrival of colder, northern air masses which foreshadow a longer, more intense winter.

Or not.

My favorite winter-intensity myth stated that when two woodpeckers share a tree the winter will be severe. I am not sure if it matters what kind of woodpeckers might be co-habitating, but I am keeping my eyes open for that one!

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Signs of Winter #2: Spruce Flats Bog

Photo by D. Sillman

Photo by D. Sillman

The visual image and history of the Spruce Flats Bog are important (to the left is a summer picture of the bog). First, like the top of most of Laurel Hill, the overall topography of this site is remarkably flat. Also, like most of the top of Laurel Hill, the rock underlying this site is a thick, hard, water impermeable layer of sandstone that is covered by only a very thin layer of soil. This underlying sandstone spreads out under the Spruce Flat Bog area in a broad, shallow, saucer-shaped pan that tends to accumulate rain water and snow melt. The formation of this depression may have been caused by the weight and movement of a ridge top glacier that formed during the last Ice Age tens of thousands of years ago. The great continental ice sheets of this Ice Age terminated many miles to the north of here, but the locally cold climate they generated and the high altitude of this ridge (2720 feet) may have combined to support an isolated mass of ice. Retreat of the continental ice sheets and the warming of the climate would have melted the ridge glacier leaving behind a broad, shallow lake that then began the slow process of pond succession and transition into increasingly solid land. Simply visualized, the pond slowly filled with vegetation and sediment, and its water tolerant plants were slowly replaced by more truly terrestrial plants that began an incremental march in from the edges into the slowly solidifying center. So, this area of open water became a bog, and then a peaty-soiled wet forest, and then, as larger and larger, more rapidly transpiring trees became established, it eventually became a dry soiled forest in which the rates of water accumulation into the saucer were balanced by the outward (and upward) transpirational loss of water by the standing trees. To have looked at this site in its forest form, the potential for a bog would have been very difficult to see!

In 1908, the virgin hemlock forest on this site (and “hemlocks” were frequently mislabeled as “spruces.” Hence, the very odd name for this bog!) was cut. Following this logging, a fire burned away the slash, the re-grown shrubs and sprouts, and also much of the humus-rich upper soil layers. The site now lacked both the sponge-like organic soil materials and also its ecological “pumps” (the transpiring hemlocks). So, rainfall and snow melt once again began to accumulate as free water in the saucer shaped depression. A shallow pond formed followed by a repeat of sediment and vegetation accumulation to form a bog. The inability of trees to grow on the site and the uninformed opinion of the worthlessness of wetlands led to attempts to drain the bog. Dynamite allegedly was used to try to fracture the underlying sandstone and allow downward flow of the bog water into ground water, but the pond/bog persisted. The donation of the land to the state and the creation of the state park protected this bog (although in other state park areas other bogs have not been so fortunate).

Photo by D. Sillman

Photo by D. Sillman

In the 1950’s pitcher plants (a summer photo of these pitcher plants is to the left) were transplanted into the bog by members of the Botanical Society of Westmoreland County, and other wetland plants (like sundews) were also, undoubtedly, introduced into the site at this time. The bog contains cotton grass, cranberry, blueberry, white cedar, pitcher plants, and round-leaved sundews. Sedges grow profusely across many areas of the bog and Juneberry shrubs line the edges of the boardwalk that connects to the observation platform that was built by the Pennsylvania Conservation Corps and Youth Conservation Corps in 1995 and 1996. Conifers (including white pine, pitch pine, Norway spruce, black pine, and eastern hemlock) have been planted around the circumference of the bog forming a tall, green, wall-like palisade on the high edges of the great depressional saucer. Some of the white pines are extremely sculpted by the strong west to east prevailing winds and have grown into fantastic, “action-shaped” morphologies.

We walk down the flat, level, and evenly graveled path and in ten or fifteen minutes are standing on the boardwalk that extends out over the shallow water and wet soil. Even in the cold air of the fading afternoon I can smell the richness of the bog. The scent, a combination of rich organic muck, water, and hydrogen sulfide, pours over me and triggers a cascade of old (and very good!) memories of coastal wetlands and hours spent mucking and kayaking through them. We have the two golden retrievers on leash so that they don’t go off splashing in the bog muck. Izzy is tired and sticking with us, so we leave her off her leash. She takes a short walk into the edge of the bog but comes back to dry land quickly.

Photo by D. Sillman

Photo by D. Sillman

The brown, dry tops of cotton grass spread out over the surface of the thick, black water. Scattered cedars of various sizes and ages stand like islands in the sea of dry grass. You can picture these little cedar islands slowly expanding as the vegetative debris steadily builds up a peat layer into which more and more rooted plants can grow. We also see sphagnum moss growing in from the edges of the bog. Its slow growth and steady accumulation will be another major player in the inevitable re-transformation of this wetland into a solid, richly organic saucer of soil. Scattered in clumps of cotton grass and sphagnum are the red “pitchers” of last season’s pitcher plants. The chambers of the pitchers are designed to lure and trap insects in an enzyme rich fluid where they will be slowly digested to harvest their body nutrients.

Insectivorous plants of the bog (like the pitcher plants) are evolutionary solutions to one of the fundamental nutrient problems of wetlands specifically and wet soils in general: the lack of nitrogen. Nitrogen is a vital nutrient needed for plant growth. Nitrogen in soil is available to plants either as ammonium ions (NH4+) or as nitrate (NO3-). In very wet soils, oxygen levels are often very low due to the inability of air to penetrate into the water filled soil profile. Anaerobic bacteria in the soil then use nitrates as the final electron acceptor in their energy metabolism instead of oxygen. This bacterial generated reduction of nitrate (which is called “denitrification”) generates nitrogen gas (N2) which then leaves the soil and joins the incredibly abundant nitrogen gas reservoir in the atmosphere. So, when a soil is very wet and anaerobic, it is also almost always deficient in nitrogen. The pitcher plants and also the sundews (which we have seen here in the summer but which are not visible here on the cusp of winter) harvest nitrogen from their ensnared insects to help fuel their growth and reproductive metabolisms

After a long hike in the confines of the woods, standing on the edge of the open expanse of the bog is peaceful and welcoming. The wind, though, is picking up and the temperature is continuing to fall. The dogs lie down on the planks of the boardwalk and leave behind perfect, muddy outlines of their legs and bodies. We are going to have to find somewhere to clean these guys up before we go back to Rob and Michele’s condo in Hidden Valley! We leave the observation platform reluctantly but with even more pace to our walking speed. It is getting dark when we get back to the cars. The soft car seats and the quickly warming heater feel unbelievably good! Definitely a sign of winter!

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Signs of Winter #1: Hiking Wolf Rocks Trail

Photo by D. Sillman

Photo by D. Sillman

Wolf Rocks Trail is in Laurel Summit State Park about five miles east from the Grove Run Trail that we hiked last month. This area, like that around Grove Run, was extensively logged in the late nineteenth and early twentieth centuries. Most of the park roads, in fact, have been built on the rail beds of the logging railroad spurs that connected into the main line of the Pittsburgh, Westmoreland, and Somerset Railroad which ran along the present day Linn Run Road. Remnants of these old rail beds (old rail ties, gravel, etc.) can still be found along some of trails.

It is difficult to visualize the activity and human and mechanical energy that filled this area just over 100 years ago. The primal forests of hemlock, white pine, and mixed hardwoods were cut acre by acre, the downed trees were dragged to the rail sidings by horses and then hauled away to the saw mills in Ligonier. There were piles of logs everywhere. The finished lumber was shipped to Philadelphia to build houses, props were cut and sent deep into the booming coal mines, and the mining companies bought entire towns-worth of lumber. Great piles of tannin rich hemlock bark were stacked along the sidings waiting for loading and shipping to leather tanning factories. Fires from the locomotives and from the boilers in the mills were common. Much of the land was cut, then burned, and then burned again. Only a few plant species could survive the incredible ecological “filter” of this destruction and stress.

Deborah and I met Rob, Michele, Nancy and Deb down on Route 30 and then drove up the rough, dirt and gravel road to the Laurel Summit State Park picnic area. We brought Izzy for another woods adventure and Nancy and Deb brought their golden retrievers, Ripley and Maizey. The three dogs handled each other well and added a great sense of the unexpected to the hike (it is amazing what dogs find when they are in the woods and what they think to do!).

Photo by D. Sillman

Photo by D. Sillman

The first section of the Wolf Rocks Trail is a young forest dominated by red maples, sugar maples, black cherries, yellow birches and red oaks. In the summer the understory is lush and green with ferns. Today, though only a few scattered evergreen wood ferns are still green and standing. All of the other species have succumbed to the seasonal changes and are brown and dry. Witch hazel trees and saplings of the over-story trees form a middle vegetative layer along with sometimes very dense stands of the still green and vibrant mountain laurel. In the deep shade under the laurel there are small patches of snow (now THAT’s a sign of winter!).

The trees on this section of the trail are very uniform in diameter (about 12 inches) and height. This homogeneity in size is characteristic of a re-growth site that was uniformly affected by a large disturbance. The abundance of northern red oak and red maple is also consistent with a forest site that has been massively disturbed. Red oak’s ability to stump sprout and withstand fire, and red maple’s ability to rapidly reproduce and, via their abundant winged seeds (“samara”), colonize newly disturbed sites fit the site history of clear cutting and extensive ecosystem fires. The secondary trees (yellow birch, pin cherry, and black cherry) among the red oaks and red maples are also all very common “early colonizers” of sites after widespread logging and fires.

Photo by D. Sillman

Photo by D. Sillman

As we move along the trail the trees become more widely spaced. The understory between them gets a great deal of sunshine and in the summer is full of a tall and lush undergrowth. Today, great circular expanses of the frost killed ferns open up along the side of the trail. White pines (from very large trees with twenty inch trunk diameters, to saplings, to tiny seedlings) “suddenly” are growing among the maples, yellow birch, and black cherry trees. Have the pines “replaced” the red oaks? Possibly the greater distances between the individual trees in this trail section favors the sun loving pines over the more shade tolerant oaks. The pines are reproducing vigorously here. Pine needles cover the trail surface in a smooth, thick, orange carpet. The scent of the pines is incredibly pleasant.

The trail surface is wet and very broken up by rocks and roots. Its irregularity demands careful attention to each step. The trail has been very heavily used. Its surface is compacted several inches below the surrounding soil levels. Surface water from rainfall probably is directed into this lowered hollow of the trail generating an on-going erosion problem. The extensive root exposure on the trail is a direct reflection of this erosive flow of surface water. Sections of the trail have moss growing directly on the soil surface and on the exposed rocks and roots. A bare, well walked step line winds its way around and through these glowingly green surfaces

Photo by D. Sillman

Photo by D. Sillman

Catbrier (also called “greenbrier”) grows very thickly among the surrounding ferns and out into the edges of the trail. The sharp thorns cut at our pant legs as we walk past. We quickly come to the juncture of the Loop Trail, the Spruce Flats Trail and the Hobblebush Trail. The Hobblebush Trail is labeled “Expert Biking Only.” Can that trail somehow be even rougher and rockier than the trail we have been walking on?

We turn onto the Wolf Rocks Loop trail which runs first to the west and then toward the northwest along the edge of the ridge that overlooks the Linn Run Valley. Through the bare trees we get glimpses of the valley. Wolf Rocks at the end of the trail will give us an unobstructed panorama over the Linn Run and Fish Run valleys and their surrounding hillsides.

American beech dominates the first section of the Loop trail. Under the beech trees are patches of a lycopodium called “ground pine.” Over three million years ago, ancestors of these fern relatives grew as massive, tree-sized plants in the wet, coastal, swamp forests of what would become western Pennsylvania. As these behemoths died, they fell into the poorly oxygenated waters of the swamps and partially decomposed into peat. These peat layers were then sealed away from atmosphere by sediment layers laid down by the rising and falling oceans. These fossilized remains became, over time, the “fossil fuels” of coal, natural gas, and petroleum that have been and continue to be so important in Pennsylvania’s economy.

The three dogs race back and forth between their scattered people walking the trail. Maizey and Izzy come back to check on Rob and I (at the back of the group again!) and then speed on up ahead to see what Ripley might have found (often deep puddles of water and mud that are perfect spots to lie down in!). All three dogs have mud-blackened legs and feet to complement their gorgeous, golden coats. They are also having a great time!
There are more wind-thrown trees on this section of the trail. We are close to the western edge of the ridge and undoubtedly the wind exposure here is greater than at the more sheltered trailhead. The power and consistency of the wind blowing in from the west all across the Laurel Highlands represents a potential energy resource. A number of “wind farms” have been built along the ridges to try to tap into this renewable resource. But, nothing is ever free or completely harmless, and the potential impacts of these wind turbines especially on birds need to be clearly understood before we rush into their widespread construction.

The Loop rejoins the main Wolf Rocks Trail at a junction we name “Jameson’s Point.” We stop and have a quick snack and break. The trail then follows a broad, flat, well walked path out to the rocky overlook. The rocks themselves are great blocks of sandstone that have begun to crack and shift away from the mass of the ridge. Ice wedging, root intrusion, and the slow, steady pull of gravity (not to mention the weights and vibrations of quite a few hiking boots) will slowly power the separation of these rocks from the ridge top. Someday, the rocks will break away and tumble down the slope to make a “rock city” on some level section of the hillside.

Photo by D. Sillman

Photo by D. Sillman

We put the dogs on their leashes as we approached the rocks and promontory. We don’t want them stumbling off of the rocks or sliding down the steep cliff face. On past visits to these rocks we have seen large rattlesnakes among the shrubby vegetation. In fact, in 2006 we saw the biggest timber rattlesnake I have ever seen in Pennsylvania coiled up under a mountain laurel bush. His warning rattle was deep and loud! It was difficult to determine his exact length but he was in a foot diameter coiled mass, repeatedly wound around himself, and his body was the diameter of my forearm. Even allowing for adrenaline induced visual exaggerations, he was impressive! But today, in early November, there are no active rattlesnakes so we climb about and put our hands and feet into crevices that we would surely avoid in warmer weather.

The sun is starting to drop down in the western sky and the temperatures are steadily falling. We zip up our coats more tightly and speed up our pace a bit as we walk the main trail back to the parking area. Red and sugar maples, red oak, black cherry, and sassafras dominate the forest. Cat brier and mountain laurel fill in the understory along with an impressive number of mostly red maple seedlings. There is a park-like feeling to the forest: widely spread trees surrounded by a uniform understory. Could the rocky soil be one of the causes of the great spaces between the trees? Along one long section of the trail the path was elevated on packed up soil and crossed several covered cross-logs that spanned sections of boggy soil that was loaded with sphagnum moss. Possibly this was an extension of the nearby Spruce Flats Bog.

We get back to the cars after a little more than three hours of hiking. We are tired, a bit footsore, and cold but decide that we need to keep going so that we can see the Spruce Flats Bog before the sun completely sets.
(continued next week!)

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Signs of Fall 11: Robins and Ring-necked Snakes

Photo by D. Sillman

Photo by D. Sillman

I hadn’t seen (or heard) a robin (good old Turdus migratorius) in several weeks. Over the early weeks of the Fall small flocks had passed over our hilltop on their south and west trajectories. Every once and a while one or two had dropped down from their flight paths and paused here in Apollo to snack on some local earthworms or grab some wild grapes, but there had been no robins for quite a while. It was exciting, then, last Saturday morning when I went out early to fill the front yard bird feeders and was greeted by a loud, unmistakably “robin” extended cackle. It took me several minutes to find the singer: it was a dark black robin with a bright red breast perched up on the almost leafless branches of my red maple tree. A Newfoundland robin!!

Robins spend their springs and summers as mated pairs with very loose flock connections. In the fall and winter, though, they form large flocks that travel locally from one feeding area to another. Many of these flocks even migrate long distances to spend the winter in milder, southern climes. The driving force that moves these flocks is food. In the late summer robins “disappear” from many places here in Western Pennsylvania much to the concern of local bird watchers. These “gone robins,” though, have just vacated one spot to concentrate themselves in some other locale that has more abundant food supplies. People living in these robin-blessed sites wonder at the population explosion going on around them and are concerned by the out-of-control expressions of nature. Deborah and I were driving out in Burrell Township (Armstrong County, PA) late one July a few years ago and were stunned by the thousands and thousands of robins that were hopping around on the ground and perching on almost every free tree branch. The noise they made and the mess they created on every surface with their droppings (is this where their genus name comes from?) were astounding!

It is interesting that although the American robin is one of the most common, most abundant, and most recognized birds in North America its migration patterns are not at all well described. I think that the lack of patterns in their year to year migrations at the onset of winter and then at the advent of spring is due to their dependence not on temperature or weather patterns or geomagnetic sensory systems (things that would be predictable and generate fairly hardwired responses) but instead it is because they follow their food supplies wherever the vagaries of the previous season generate scattered spots of abundance.

American robins are found all over North America. They summer and breed in Canada and Alaska, spend the entire year and breed all across the continental United States, and winter down to southern Mexico and even just a little further south into Central America. The mid-February “arrival” of the robins here in Western Pennsylvania is major sign of spring but probably represents just the ebb and flow of locally overwintering populations transiently leaving their sheltered (and probably fruit filled!) hollows and valleys on short forays out into suburban landscapes to look for earthworms in thawing acres of yard grasses.

I am familiar with three of the seven subspecies of T. migratorius. The subspecies here in Western Pennsylvania is the classic (or “nominative”) form of the American robin. It is widely distributed across the northern United States and Canada all the way north to the very edge of the tundra. The “Newfoundland” subspecies (whom I think that I saw up in my tree last Saturday) has darker black back feathers and redder breast feathers than its nominative subspecies. It may also be (in my opinion anyway, although I could find no reference that agrees with this!) slightly larger than our “usual,” nominative robin. These “Newfoundland” robins may simply represent a color form that is out on one extreme of the species normal color distribution. “Black backed” robins can be seen almost any time of year through the bird’s North American distribution. But this dark, intense coloration does seem to predominate in the robins from Canada’s northeastern coast. The third subspecies is the “Oklahoma” robin. This robin’s back feathers are more gray than black, and it has a pale, reddish orange breast. They look dusty and dry (as is fitting the dust-bowl center of their distribution). When I visited my parents in Tulsa these are the robins I would watch ranging across the suburban lawn-scape as they searched in the coarse grasses for worms.

Photo by David Hoffman (Flickr)

Photo by David Hoffman (Flickr)

Changing the subject to snakes! My good friend Carl Meyerhuber called me last weekend to report a sighting down on the Roaring Run Trail. Near the Canal Street parking lot Carl spotted an immature ring-necked snake crawling slowly across the trail. It seems very late (and it has been very cold!) for these delicate snakes to be out and about. It was a good thing that Carl was there to make sure that this slowly crawling, well chilled young snake made it all the way across the trail!  Last summer I wrote about ring-necked snakes and said that in spite of the DER’s declaration that they are one of the five most common snakes in Pennsylvania I had never seen one. They are shy and nocturnal and hard to find. I hope that this little immature ring-neck found a suitable place to hibernate down in the vegetation beside the Kiski River. I will look around for him next summer!

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Signs of Fall #10: Where do the frogs go in winter?

Northern green frog (photo by Contrbaroness. Wikimedia Commons)

Northern green frog (photo by Contrbaroness. Wikimedia Commons)

A few weeks ago Jane Viti, one of my teaching colleagues, asked me what was going to happen to the two frogs that had been living in her small, backyard pond all summer. As we talked about her frogs’ appearance, behavior, and songs I decided that they must be Northern green frogs (Lithobates clamitans melanota), and since her pond is quite shallow and expected to freeze solid over the winter, and also because it is surrounded by a very dense growth of myrtle, I speculated that the green frogs (which can either hibernate underwater or underground) would leave the soon-to-be-solid pond and dig a hibernaculum in the soil under the protective cover of the myrtle. But where these frogs sit out the winter was just the beginning of this story. Frogs are ectothermic (they rely on the heat of their environment for their body heat) and would seem quite vulnerable to freezing solid in the very cold winters of Western Pennsylvania even if they were underground or underwater. How could they survive this extreme thermal trauma?

In my Cell Biology class I talk about changes that can be seen in cell membranes in both amphibians (like the green frog) and reptiles (like turtles and snakes) as seasonal temperatures begin to fall. An enzyme is stimulated that begins to add double bonds to the fatty acids of the cell membrane phospholipids. This “desaturase” enzyme makes the altered fatty acids more crooked and thus less able to stick together. This reduces the freezing point (which usually referred to as the “melting point” for some reason) of the cellular membrane and keeps the membrane “fluid” and functional at lower and lower temperatures. Also, amphibians add cholesterol to their cell membranes, and these steroids further keep the fatty acids from clumping together even at decreasing temperatures.

These changes help to keep our frog active at temperatures that are lower than optimal, but eventually temperatures start to approach the freezing point of water, and the frog is at risk of cell and tissue damage from the freezing of the water in its blood and cytoplasm.

Frostbite on human toes (Photo by Dr. S Falz-Colleque Wikimedia Commons)

Frostbite on human toes (Photo by Dr. S Falz-Colleque Wikimedia Commons)

Let’s take a second and think about people. When skin is exposed too long to freezing temperatures cells are destroyed and “frostbite” occurs. Why do the cells die? First, the blood flow into the cold body part is curtailed in order to prevent excessive body heat loss (humans are endothermic organisms who use the heat from their metabolic activities to generate their body heat and there is only so much heat energy to go around!). The lack of blood flow into the tissue means that oxygen is no longer being delivered and cell death from lack of oxygen may occur. Also, and maybe of a more immediate concern, the lack of warm blood entering the tissue means that the fluids in the tissue and in its cells may start to freeze. Usually the interstitial fluid around the cells freezes first and these ice crystals actually start pulling water out of the inside of the cells. For a while this dehydration event may actually hold off cytoplasmic freezing, but eventually the cell will be irreversibly damaged (i.e. “killed”) by either excessive dehydration or by the inevitable freezing of its cytoplasm.

But, let’s get back to our frogs: before the frogs are exposed to freezing temperatures they undergo many physiological changes in addition to the cell membrane changes I listed above. Their livers start synthesizing and releasing large quantities of glucose (“sugar”) into their blood streams. These sugars are absorbed by the cells of the body causing the cytoplasm to become thick and syrupy and increasingly hypertonic to the surrouding interstitial fluids. Also the frog releases special proteins called Protein Ice Nucleases (or “PIN’s”) into their blood stream. These proteins will stimulate freezing of the water in the blood stream which will then inhibit the potentially lethal freezing of the water of the cytoplasm inside the cells! When the frogs are finally exposed to truly freezing temperatures the skin and then the rest of the body freezes solid (they are like little rock statues of frogs!), but the freezing is primarily confined to the blood and to fluids around the cells! The forming ice crystals in the interstitial fluid draw water out of the cells (just like in human frostbite) but the high levels of sugar inside the cells not only act as a natural antifreeze for the cell but also hang onto enough water so that the cells don’t dehydrate to the point of death!

Gray tree frog (photo by L.A.Dawson. Wikimedia Commons)

Gray tree frog (photo by L.A.Dawson. Wikimedia Commons)

Terrestrial frogs (like the American toad (Bufo americanus), the wood frog (Rana sylvatica), the spring peeper (Hyla crucifer), the gray tree frog (Hyla versicolor) and the northern green frog when it decides to hibernate on land) basically let themselves freeze solid in their soil hideouts. Wood frogs and tree frogs don’t even go down into the soil but just bury themselves in piles of leaves and ride out the months of freezing temperatures. During warm spells these terrestrial hibernators may even thaw out and move around, but they will typically then re-freeze and settle back into their winter slumbers. I noted in several spring and summer blogs this year the very large number of gray wood frogs in the trees around my field and yard. I wonder if all of the leaves that I have been letting pile up under my trees (because of my selective leaf-raking policies) provided these great creatures with sufficient winter habitat to favor the growth of their population?

Aquatic frogs (like the leopard frog (Rana pipens) and the American bullfrog (Lithobates catesbeianus) and the northern green frog when it decides to overwinter in a body of water) spend the winter if not frozen then nearly so in the still liquid environment of their ponds or pools. They do not bury themselves in the muds of these systems because they must continue to pick up oxygen from the surrounding water through their skin. Sometimes they sink to the bottom of their pools or ponds (they are quite solid and have no air in their lungs) but they must keep contact with the oxygen-rich water in order to survive. They also may swim about a bit when they warm up during lulls in the winter cold. Aquatic frogs can survive freezing solid in ice, but I don’t know how long they can live that way. The lack of oxygen would surely be fatal if the ice-encasement persisted for too many weeks.

So, on the next cold Fall night as you sit in your warm house wrapped in an afghan or a sweater, give a thought to the little frozen frogs outside who are waiting for their personal Spring thaws to come.

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Signs of Fall #9: Grove Run Trail (part 2), Striped Maples and More Rocks

Photo by D. Sillman

Photo by D. Sillman

(Portions of this blog posting are taken from my hiking essay about Grove Run Trail (on the “Between Stones and Trees” web site))  (Continued from last week)

We crossed the narrow wooden bridge over Grove Run. The stream bed was filled with rocks and fallen trees. Some of the rocks had been deeply grooved by the water flows, but there was no flowing water today.

Across the bridge we climbed steadily up the slope on the opposite side of the deep hollow and headed, in general, to the east. The trail followed a small tributary of Grove Run back up the ridge. This side of the hollow faced the northern sky. In this more shaded environment, American beech saplings and pole trees became increasingly abundant. Beeches should grow especially well in this ravine. The cool, moist conditions are ideal to nurture this slowly growing species, and the near immunity the beech seedlings have against deer browsing will greatly favor its persistence.

Photo by D. Sillman

Photo by D. Sillman

The trail surface was covered with rocks that seem to get larger and larger as we hike up the ridge. We had to pay close attention to each footfall and were forced to stop when we wanted to look around or try to take in the beautiful scenery and day. The walking was hard, and Rob and I agreed that we were glad that we were wearing boots and had hiking sticks. Deborah was in tennis shoes and never uses a stick. She and Michele were also probably a half a mile ahead of Rob and I by now. As I stumbled along looking to my footing I wondered how they were going along so rapidly! Different hiking techniques, I guess.

There were even more downed trees along this section of the trail than in the previous one. There were great stacks of fallen tree trunks piled up on the slopes and scattered down into the deep recesses along the stream. There were extensive areas of open canopy generated by newly fallen trees and abundant zones of sunlight that illuminated the forest floor. The “sun spots” were especially filled with yellow poplar and red maple seedlings.

We turned left and walked due north up a side hollow crossing several small, dry stream beds. We hike up and up on long switchbacks that were edged by briers and nettles. In one section of the switchback trail someone has cleared away most of the path rocks and lined them up neatly along the left side of the trail. Suddenly, it was very easy to walk! The twisting, jarring strain on the ankles, knees, and back with each footfall was gone! Our walking pace picked up. It was possible to look around while walking without fear of missteps. The trail was clear for about a quarter of a mile and then reverted back to its un-managed state. The memory of the cleared trail, though, actually slowed us down as we twisted and stepped up through the continuing rocky footpath.

Photo by D. Sillman

Photo by D. Sillman

The trail surface and most of the surrounding boulders are covered with moss. Everything was green and soft looking and must spend a great deal of its growing season in a wet state. The “up” continued and we passed into an increasingly dry forest dominated by oaks. Chestnut oaks, often very large specimens, fill in the surrounding woods inter-mixed with red, black, and also white oaks.

At the top of one of the switchbacks there was a trail register and a sitting log. We had caught up to Deborah and Michele and stopped to have a water and gorp break. Izzy ate four dog biscuits and drank two Sierra cups of water. A group of teenagers came up the trail from the opposite direction. They were staying in the Linn Run cabins and were out for a stroll. They didn’t look nearly as tired as we felt! They petted Izzy (once she stopped growling at them) and headed on down into the ravine.

Photo by D. Sillman

Photo by D. Sillman

Most of the trees on the ridge top were striped maple. This is a tree species of some poor reputation among foresters. Their idea, of course, of a “poor” tree is heavily influenced by the economics of that tree’s wood. Striped maple is not a tree from which any lumber or wood products could be easily made. Whatever the future potential of this tree is, though, along this ridge it was generating a rich habitat that in the summer at least is full of birds!

Striped maple is also called “moosewood” in places, I assume, that have the luxury of having moose. It is a small tree or large shrub that thrives in cool, moist, but well drained sites. It is found throughout the northeastern United States and across southern Canada. It makes up part of the understory vegetation in a wide variety of forest types.

Striped maple can live in the deep shade of a forest for many decades in a slow growing, suppressed state. Over these decades, in spite of a very high mortality rate in its first year seedlings (9 out of 10 seedling die in their first year of life), very large numbers of individuals can accumulate in the forest system.

Canopy disruption allows increased light to reach this understory triggering a vigorous growth response in these suppressed striped maples often to the great disadvantage of other, less abundant seedlings. Forests that have striped maple making up 30% or more of its total seedlings typically will generate after clear cutting nearly pure striped maple stands. These ridge forests, then, must have had dense undergrowths of striped maple that were released when the larger trees were cut or burned.

Deer browse heavily on striped maple. Rabbits, porcupine, and moose (hence the “moosewood” name!) also readily eat it. Beaver will even take striped maple if their preferred aspens are not available. The very large number of individual trees that build up in a stand, though, and their rapid potential growth rates upon release from shade suppression, enable this species, unlike many of its less abundant or less robust competitors, to thrive in areas even with very high deer populations.

Striped maple flowers in May or June and has a very interesting “gender” story. Most striped maple individuals are either “male” or “female” and, thus, only set either pollen synthesizing flowers or ova synthesizing flowers. But, from year to year, an individual tree can either be male or female. Environmental variables are thought to determine the yearly gender of a particular tree.

In a stand of striped maples there are always many more female trees than male trees, and these female trees, undoubtedly due to the extreme energetic demands of seed production, are much less vigorous than the males. In fact, in one study 65% of the female striped maple on site died by the end of the growing season.

The seeds in winged samaras are wind dispersed in October or November and may germinate the next growing season or, possibly, the season after that. Birds (including ruffed grouse) and many types of small rodents eat striped maple samaras, but, again, overwhelming numbers insures the survival of more than enough seeds to fuel the explosive growth of seedlings in the forest understory.

We crossed the broad, open Quarry Trail (part of the snowmobile trail system that crisscrosses the Laurel Highlands) and continued on the Grove Run Trail. The red blazes were set very far apart and in places the trail was so covered with rock that it was difficult to see the path. We focus on the blazes and keep on the trail.

Years ago, Deborah and I were caught in a large thunderstorm up on this section of the trail. Lightning and thunder, torrential rain, and hale pounded on us for over an hour. Today, thankfully, the skies stayed clear and blue. It was hard enough walking on these rock paths without having them coated with water and ice!

Photo by D. Sillman

Photo by D. Sillman

The remaining trail was all side-hill cuts into a very steep slope. The pull to the downside of the slope really strained our knees and ankles. You felt like you could go tumbling down the slope with even a tiny stumble. To our right was the valley of Linn Run and all around us were stands of beautiful oaks and red maples and great expanses of ferns.

We had been hiking for two and a half hours. The end of the trail should be close but everything seemed to stretch out to longer distances that we expected. At one point the trail even turned back uphill! That didn’t seem right (or fair) but we stuck to the red blazes and pushed on. Deborah and Michele were far ahead of Rob and me and even told other hikers heading up toward us to say “hello” and ask if we “needed a rescue party?” (what great sense of humor, eh?). One woman with a young, bouncing golden retriever asked me “are you Izzy’s owner? She’s so cute!” They must have had a pleasant encounter.

We stretched out the last mile and finally got a glimpse of the Grove Run parking area. Deborah and Michele were sitting with Izzy around the blister beetle fire ring. Deborah has used her scarf for an Izzy leash (the actual leash was in my pocket). Rob and I had the car keys, too. We were also carrying the extra water and all of the trail snacks. We sat down and, eventually, agree to share (we have a sense of humor, too!).

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Signs of Fall #8: Grove Run Trail (part 1), Blister Beetles and Rocks

Photo by D. Sillman

Photo by D. Sillman

(To read more about the Grove Run Trail check out my “Between Stones and Trees” hiking web site))

A couple of weeks ago on a beautiful Saturday morning Deborah and I met Rob and Michele Bridges down in Lynn Run Sate Park for a hike. The woods around Linn Run are a second (or, maybe, even a third or a fourth!) growth forest that date back to the first decade of the Twentieth Century. This was one of the first tracts of land purchased by the State of Pennsylvania (in 1909) in its efforts to reclaim and protect potential forest lands in the Ohio River watershed. When the state bought the land (much to the derision of the local inhabitants), it was a scrubby, tree-less tract dominated by ferns and briars and was almost completely devoid of wildlife or beauty. Not only had the woods been clear-cut by logging companies, but extensive fires (often caused by sparks thrown by the logging railroads) had repeatedly burned off the early successional recovery stages. It was a pretty miserable place!

The passage of time, though, has been kind to this area. With our region’s abundant rainfall and diverse seed reservoirs, a century of robust re-growth of the forest ecosystem followed in spite of the thin, rocky soils and continued sequences of insults and stresses.

Linn Run is shallow, rocky stream. It has a fast pace and lots of splash and foam and now has an abundance of trout and other fish. The forest that fills in the spaces around the narrow road that follows the run is lush and moist with the spray from the creek. Ferns and mosses grow in great abundance along the streamside. Hemlocks, yellow birches, and red maples crowd the edges of the creek and hang their dense branches over the water frequently generating a continuous tree tunnel over the path of the creek. It is a shady, cool place even on the hottest summer day. The hills and ridges around Linn Run through which our hiking trail will pass vary in elevation from 1300 to 2800 feet above sea level. Many of the trails climb up steep slopes in long switchbacks that are carved directly into the hillsides. All of these trails are covered in by layers of cobble-sized rocks that are a great challenge for a hiker’s feet and ankles!

Deborah and I parked in the picnic area of Grove Run (a small tributary of Linn Run) and sat beside a large fire ring to wait for Rob and Michele. Our dog, Izzy, was with us and was very excited to be away from home (or maybe she was terrified at being away from her familiar territory, it’s hard to tell with her sometimes!). She ran from scent to scent in the picnic area adding her scent to the olfactory symphony until she ran dry. She also growled at every large dog (and they were all larger than her!) that walked by. She was full of energy that amazingly did not flag throughout the long, rocky hike that we are about to start.

Photo by D. Sillman

Photo by D. Sillman

Deborah and I watched a male and a female blister beetle walking around in the cleared area around the fire ring. The blue coloration of these beetles announces their presence and also their potential toxicity to any potential predator. This type of warning coloration is called “aposematism,” and it benefits both the beetles (who are able to avoid being eaten) and predators (who avoid getting blasted with the caustic cantharidin secretions produced by the beetle). The physiological steps by which the cantharidin is synthesized and violently released make blister beetles great biological curiosities. They are often used as examples of the unexpected outcomes of evolutionary selection.

The two beetles were mating. The much larger female dragged the attached male around the fire ring. A second male blister beetle showed up but was out of luck for this encounter. This was late in the year for these beetles to be mating. July is usually the peak time for reproduction because the beetle’s eggs and larvae have to have several months to go through all the required developmental changes needed to get them ready to overwinter. The female blister beetle can produce up to six clusters of fifty to three hundred eggs and will deposit these egg masses in the ground or under rocks. A week and half to three weeks later the eggs hatch into first instar larvae which then seek out grasshopper egg cases. The larvae voraciously feed on the grasshopper eggs and go through increasingly larger and more sessile stages until they reach their fifth larval instar. The fat, almost legless fifth instar “grubs” then dig down into the soil where they molt into the sixth instar stage. The sixth instars overwinter and sometimes actually stay in their subterranean hideouts for up to two years! Usually, though, these sixth instars pupate in the spring and then emerge as adults in the late spring or early summer.

Photo by D. Sillman

Photo by D. Sillman

Rob and Michele arrived so we tore ourselves away from the dancing blister beetles and headed off on the old logging road that makes the start of the Grove Run Trail. The lushness of both the undergrowth and the canopy trees is striking. Many tall yellow poplars, red oaks, black oaks, sugar maples, red maples, black cherries, and scattered basswoods, cottonwoods, and American beeches fill up the spaces in the forest.

In 2008 (when I wrote the hiking essay about this trail) there were abundant American chestnut seedlings in the understory of this first section of the woods. I took that as a hopeful sign that some individuals of this formerly abundant tree might be eking out an existence in these ecosystems. I looked carefully to see if the seedlings have survived and grown, but they were no longer here. They must have succumbed to the lethal fungus that causes chestnut blight. The yellow poplars that were growing with them, though, were flourishing.

Photo by D. Sillman

Photo by D. Sillman

On the trail, there is a grace and spacing of the trees that seems almost managed and park-like. This openness is the dominant feature of the trail for many hundreds of yards. As a consequence of this spacing abundant sunlight reaches the forest floor and a rich growth of plants is seen in between the trees. Stinging nettle, cat briar, hay-scented fern, interrupted fern, sensitive fern, Christmas fern, jewelweed, partridgeberry, and extensive patches of blue cohosh grow densely along the trail and out into the surrounding forest. Seedlings of yellow poplar, American beech, red maple, and striped maple grow in clusters among the ground plants and form a dense, green “sea” in between the rich mixture of mature trees. Witch hazel, spice bush, and dogwood generate a scattered understory layer, and near several of the oaks are odd, brown, pine-cone-like patches of squawroot.

The trees are very uniform in diameter (and, therefore, I infer, they are very uniform in age). At the start of the trail trunk diameters of over a foot were common, but soon diameters of significantly less than a foot became the norm. These younger trees generate a “pole forest” that runs up the surrounding hillsides and down the short slopes to the stream. Along the way, there are a few very large, widely dispersed red oaks. These trees might have either survived the early logging or, at the very least, the initial rounds of fire that leveled the recovering forest.

Photo by D. Sillman

Photo by D. Sillman

There are many downed trees and fallen branches along the trail. Large trees, often wind-thrown with huge, still attached root balls lay in regular lines mostly perpendicular to the path. Some of these fallen trees are old and are covered with mosses, lichens, fungi, and even stands of robustly growing tree seedlings. Others of the fallen trees have bare, intact bark and look like they might have come down quite recently. Most of the fallen trees are yellow poplars with a much smaller number of oaks. Most of the seedlings, though, growing on and around these fallen trees are yellow poplars. The shallow, rocky soil of this ridge undoubtedly was the cause these very numerous wind throws. The cycle of canopy disruption, light influx, and the consequential growth of seedlings favors the very rapidly growing, sun-loving yellow poplars over the oaks. It is possible that this “dynamic equilibrium” of wind throw disturbance and re-growth will result in a persisting, yellow poplar “climax community.”

On past hikes of the Grove Run Trail we have seen abundant birds. In particular many species of warblers were active in the dense forest understory vegetation. Today, though, there are no birds. We are far too late in the season for them. We heard what might have been a grouse chucking in the distance, but no warblers, no woodpeckers, and no towhees sang us along the trail. There were not even any crows raising commotions up in the trees!

The trail followed the curve of the hollow back into deeper and deeper forest. As we hiked up away from Grove Run, the trees grew closer and closer together. The forest and the trail got darker and quieter. The breeze faded away and the undergrowth supported more and more ferns. There are some very large yellow poplars here and increasingly abundant basswoods and red maples. There are also more downed trees that are surrounded by dense growths of yellow poplar and striped maple seedlings. We climbed along the slope on a laboriously carved side-slope trail that was cut all the way down into the underlying rock. There were many rocks and fallen trees all up the sides of the ravine. The uneven trail surface and the necessity of climbing over fallen tree trunks became more and more exaggerated as we go along! THIS was a hard 4 miles!

Michele and Deborah and Izzy walked out ahead of Rob and I. Soon we no longer could see or even hear them. The forest was dense and quiet and surprisingly dry. The surrounding creeks and rills were quiet and have hardly any trickles of water flowing in them. The trail was marked with red blazes. There were older, blue blazes, too, often on downed trees and sometimes painted over with a slap of red

Downed logs have been sawed and pushed off the path, and, very significantly, the stinging nettle and greenbrier has been cut back from the narrow path to make a three or four foot wide swath through the woods. Warm weather, to me, demands hiking shorts (and it was seventy degrees at the peak of our hike!), but the abundance of greenbrier and nettle on this trail might make one consider wearing long pants.

(continued next week!)

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Signs of Fall #7: Falling Leaves and Compost

Photo by D. Sillman

Photo by D. Sillman

I am waiting for the leaves to start to fall from my trees. It is an event that occurs at the same time each year (sometime after Columbus Day and before Halloween) but it always seems to be late in coming. I am not sure why I am always so eager to get on with the Fall, it just means that winter is closing in on us and that the color green is going away for five months!

There are so many “truths” and “myths” about tree leaves and what you need to do with them after they fall. One lawn product company stated on their web site that you need to rake up and dispose of these leaves or else “you will get rats in your yard.” Yeah, right. One of my neighbors piles his leaves in a great mass on top of his cleaned out garden and sets them on fire (or tries to set them on fire, anyway). The resulting smudgy, smoky mess smolders for hours and hours and triggers asthma in everyone for blocks around. One of my other neighbors runs her riding mower over and over her yard to scoop any stray leaves. I am not sure what she does with the mower bag’s contents. Another neighbor runs his leaf blower from August to November pushing his leaves to somewhere out of sight. His hearing must be destroyed by the din of that blower!

Photo by D. Sillman

Photo by D. Sillman

I usually rake up my leaves into several large, strategically located piles around my yard and leave them to nourish the worms and beetles and other invertebrates that will shred and grind them up into food for fungi and bacteria. In the old days my kids and I would jump in the leaves and further accelerate their fragmentation. Now I just rely on the worms to do the job with less noise and vigor (and much less fun, too!). Through the next spring and summer birds (especially the robins and the cardinals) peck at and dig around in the leaf piles looking for insect larvae and earthworms. These leaf piles are a great source of nutrition for these hunters and gleaners. By the time the next fall rolls around, the piles are remarkably reduced in size and are ready to be renewed by the freshly raked up leaves. One pile down in my orchard was kept in this yearly equilibrium for over twenty years. The rich, humus that accumulated at the bottom of the pile eventually was raked up and added to the soil of my tomato patch.

In a forest, the fallen leaves spread out in a thin layer over a broad area. Often earthworms start working on these leaves right away, pulling them into their middens and burrows, grinding them up with their muscular mouth-parts and gizzards, mixing them up with ingested soil, and defecating them out in nutrient rich, erosion resistant pellets. In soils without earthworms, numerous arthropods of many sizes begin to slowly chew away the leaf materials making a fine powder of organic residues enriched with bacteria. Both the worms and the arthropods are setting the table for the bacterial and fungi that then steadily work away at the less resistant molecules in the leaves. Like in my leaf piles, by the time the next fall comes around what’s left of the old leaves serves as the base for the new and the decomposition process grinds on.

Photo by D. Sillman

Photo by D. Sillman

Another fate of some of the leaves that fall in my yard is my household compost bin and pile. I collect a couple of trashcans of dry, freshly fallen red maple and apple leaves each fall and store them over the winter in my garage. When I charge up my composting bin in the spring, I throw in a good amount of the dry leaves to serve as a carbon source for the brewing compost and to give the dense, wet kitchen materials (usually dominated by coffee grounds!) some structure and air spaces. After some weeks in the bin (with regular turning and weekly additions of fresh kitchen materials) I shovel out some of the compost and transfer it to my nearby compost pile. Then I add some more leaves to the bin. By the end of the summer I have a rich pile of compost ready to be used in my garden or Deborah’s flower beds.

My leaf piles decompose more slowly than the managed compost piles primarily because of an innate nutrient imbalance in systems made up simply of leaves. There is too much carbon on these piles and not enough nitrogen. In the compost bin and pile the kitchen materials (especially all of those coffee grounds!) need the extra carbon of the leaves to balance out their decomposition. On the forest floor the richness of the chewing and shredding and burying organisms add nitrogen to the leaf materials via their feces and accelerate and balance the decomposition of leaves.

Natural decomposition is best thought of as an ensemble effort of an entire community of organisms where the products of one group of species becomes foods of another group of species until the food energy in the decomposing leaves is exhausted and only humus is left.

An old friend and mentor of mine, Daniel Dindal, summarized this community concept of composting into a very visual diagram that he called the “Food Web of a Compost Pile.” Please look over this marvelous work of art and science!

Drawing by D.L.Dindal

Drawing by D.L.Dindal

Up on campus we have started a composting system for the materials generated in the Café. We have three fence-sided compost bins into which we are putting kitchen and post-use “waste” materials. We are monitoring the rates and directions of the composting process, and I have three students who are conducting experiments on various stages of the composting system. Hopefully, in the spring we will have some rich compost to add to the flower beds and tree plantings around campus.

 

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Signs of Spring 6: Return of the Stink Bugs!

Photo by D.Sillman

Photo by D.Sillman

When I sit at my writing desk I spend as much time as possible looking out the window at the ongoing events in my backyard. A few days ago my view of a blue jay digging around in my compost pile (he was looking for, finding and eating fragments of egg shells!) was interrupted by the arrival of an organism that I haven’t seen since the end of June: the brown marmorated stink bug (which is frequently referred to as “BSMB”)!
One of these exotic invasive stink bugs attached itself onto the outside of my window screen and was walking around in a tight circle. When I looked back up a minute or so later, there were seven of them slow dancing around each other. They have been increasing in numbers ever since.

These stink bugs have spent the summer out in the surrounding vegetation (especially in my grape vines and apple trees, I am sure). They are the progeny of those stink bugs that survived their winter hibernations and managed to mate this past spring. Each mated female could have laid three hundred eggs which would have quickly hatched into the first of five immature, instar stages. These growing immature stink bugs spent the next two months feeding and growing and hiding out in the vegetation until they molted into their adult forms. They then started to look for a safe place to spend the upcoming winter.

Bill O’Hara (Dee’s husband) caught thousands of adult BMSB’s last fall. He used one liter, plastic, screw-top bottles with some soap solution in the bottom and took advantage of the typical escape behavior of the stink bug (they drop straight down when disturbed!) to induce them to fall into the bottle and the killing soap. Deborah and I had tried to be tolerant of the BMSB’s but their numbers finally overwhelmed even our ecological sensibilities. We used the “O’Hara method” this past spring as thousands of stink bugs emerged from their winter hibernaculae inside and around our house. We filled up several bottles a week with dead and dying stink bugs. When we had house guests we gave everyone their own stink bug bottle so that they could contribute to the correction of this exotic species invasion! We were the perfect hosts!

D. Lance Wikimedia Commons

D. Lance Wikimedia Commons

As I mentioned last year, the brown, marmorated stink bug (scientific name: Halyomorpha halys) is a relatively new sign of fall here in Western Pennsylvania. It is a native of northeast Asia (Japan, Korea, and China) and, apparently, is just as annoying there as it is here! Its use of human habitations as hibernation refuges, and its ability to communicate via pheromones and then aggregate in great numbers in some selected house, barn, porch, garage, or any other stink-bug-determined-suitable building makes their presence both in their native and also in their invasive regions impossible to ignore.

It is thought that this insect was first released into the United States in Allentown, PA in 1996. It apparently traveled from northeast Asia in a shipping container that was delivered either to the port of Philadelphia or Elizabeth, New Jersey and then trucked to Allentown. Five years later this new, alien, invasive species was recognized and identified by entomologists at Cornell University, but by then large populations were established throughout eastern Pennsylvania, New Jersey and New York. This insect has now spread to thirty-five states primarily in the eastern United States. It has very large populations in Pennsylvania, Maryland, Virginia, New York, New Jersey, Massachusetts, Delaware, Ohio, and North and South Carolina. It has also spread to California and Oregon allegedly in a car driven by a person traveling from Pennsylvania to California in 2005.

Here in Western Pennsylvania our first, massive fall outbreak of brown marmorated stink bugs was in 2010. Two of my students since then have gotten interested in the species and have done some research into their biology and ecology and even conducted some experiments to determine the species’ habitat selection preferences. I had hoped that their research would result in an effective stink bug trap, but we’re still working on that!

There is a consortium of university and government researchers who are looking into the basic ecology and biology of the brown marmorated stink bug. Their goal is to come up with effective control measures to stem this growing biological invasion. The group (called “Stop BMSB”) is funded by the US Dept. of Agriculture and includes fifty researchers from ten universities (including Penn State!). They are even conducting a “citizen’s science” survey this fall to try to determine some of the ecological and behavioral features of this bug. Their “2014 Great Stink Bug Count” asks homeowners to go out around their houses every day to determine the numbers and locations of any stink bugs that are present. If you are interested in participating, the URL for the group is www.stopbmsb.org. Maybe they can figure out what that better stink bug trap should be!

So far, the stink bugs are only on the outside of the house, but they will start to slip in soon. We are saving up screw top bottles. Drop by anytime for a lesson in the O’Hara technique!

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