Ecologist's Notebook

The content of this blog is created by Dr. William Hamilton, Assistant Professor of Biology, and Ms. Deborah Sillman, Senior Instructor of Biology, at Penn State New Kensington.

The contents of this site are licensed under this Creative Commons license. 

 

If you would like to read more, please visit:

The Virtual Nature Trail at Penn State New Kensington

Between Stones and Trees: An Ecologist Hikes Western Pennsylvania

In a gap between finals and rain showers Deborah and I went down to the Roaring Run Trail for a late morning bike ride and walk. There were very few people on the trail and, so, lots of "real" things to see.

I had to keep my eyes on the trail ahead of me as I pedaled along because there were dozens and dozens of large North American millipedes (Narceus americanus) crossing the trail. These millipedes thrive in cool, moist forests that are full of leaf and woody debris. They are important components of the decomposer web by which carbon in plant materials are cycled into soil organic matter and nutrients are recycled for new plant growth. They are large but quite harmless to people. They can, however, secrete a yellow liquid when disturbed that can stain your fingers. These millipedes are eaten by many birds, amphibians and reptiles, and they are a particularly favorite food of shrews. I managed not to run any of them over, but there had been some millipedes beforehand that were not so lucky.

The tent caterpillars were thick especially on the various kinds of cherry trees along the trail. They are an inevitable sign of late spring that is not as beautiful as some we have talked about previously, but they are the principal food of one of the glorious birds in our area: The Baltimore Oriole. As I wrote in a blog exactly one year ago today:

    "The oriole males are vying with each other for prime breeding territories and are getting ready for the anticipated arrival of the females. Baltimore orioles (and this species is distinct from Bullock's oriole so recent attempts to lump both species together as the "northern oriole" are not valid) spent their winters in southern Mexico and Central America and then in the spring spread themselves out across their breeding territories in the United States from North Dakota to Maine and Oklahoma to the Carolinas."

Further down the trail a male wood thrush perched on a branch at the edge of the hillside woods and flicked his tail at me as I biked past. His rufous colored head feathers and sharply streaked white breast were breathtakingly beautiful. These males have, like the orioles, just arrived from Mexico and Central America and are contesting with each other for breeding territories as they wait for the arrivals of the females.

I continued down the trail toward the town of Edmon when I heard the distinctive "chip-brrrr" call of the male scarlet tanager. I stopped my bike and looked up into the tall, spindly trees along the riverbank. I could see three birds as gray blurs against the bright, back-lit sky. Finally one of them flew to a point where I could see his color: bright red. These three male tanagers were also busily involved in a pre-mating contest. They had just flown in from Peru or Bolivia and were marking off and arguing about the twenty-five acres of woodlands they each require for a successful mating nest.

Indigo buntings flew through the tangled branches in the thickets near the Roaring Run creek crossing. A pileated woodpecker called and pounded on trees back near the main parking area. There were great birds everywhere!

Some of the early spring wildflowers (including the trillium) are still blooming along the trail. There are also new waves of flowers coming in. Fire pink, in particular, has taken over almost every crumbling slope along the newer parts of the trail. Its bright red petals stand out sharply against the bare, black soil of the slopes.  Fire pink was the flower that Deborah and I saw every day of our Baker Trail hike two years ago. As we hiked north we followed its blooming phases all the way to the Allegheny Forest.
 
I am still waiting to see the grosbeaks and the towhees, but spring is steadily moving into summer.

It would be very hard not to have noticed Spring racing in all around us over these past two weeks of unseasonably warm temperatures. Though we often have late March days that warm up close or into the 80's, for us to have so many days in a row with those temperatures (record highs were being set repeatedly throughout the northeast and northern mid-west) is something quite historic!

So what signs are we seeing in all of this "March-Summer?"

The hillsides took on a reddish haze as the very abundant red maples opened their flower buds (the red maples in my yard flowered on March 15, just like last year). This is the time of year to really appreciate how this once very uncommon tree of the northeastern primal forests has now become one of the most numerically abundant in our present day, human-modified forests.  The red maple flowers, though, are quickly fading and falling and are rapidly being replaced by opening leaf buds.

In the woodlands along the roads you see a growing glow of green in the understory vegetation and in the edges of the wooded "ecotones." Much of this green is being generated by the early leafing out of multiflora rose, a very abundant and invasive alien species that is doing a great deal of harm to native plant species in our forest and field ecosystems. Again, this is the time of the year to observe the extensive distribution of this plant and to reflect on the havoc humans have wrought on the ecosystems around us.

The willows along the Kiski River have been leafing out and greening up for a couple of weeks now. The raspberry canes on the edges of my field have just begun to pop out their leaves, and the slippery elms at the bottom of my field are doing the same. Green is becoming a richer component of our surroundings! (now if we can just keep the grass from growing a little while longer!)

But, it is yellow that is the true color of Spring. The daffodils and the forsythias are positively glowing around the yards and fields and down in the hollows. The colt's foot have been blooming for several weeks along the roadsides, and dandelions have even opened up on the edges of my yard.

Waiting for the spring warblers and other tropical migrants to return!  
More to come!

I went for a walk yesterday along the Roaring Run Trail in Apollo, which follows the Kiski River for quite a ways.  After a week of weirdly warm temperatures for mid-March I was not surprised (well, I was a little surprised) to see the array of wildflowers that were blooming.  Many of these often hold off to early April in a more typical year.
Here are a few examples (and you can click to see a larger image):

Bloodroot and Spring Beauty                 Great Chickweed












Yellow Corydalis                                 Dutchman's Breeches            

The flower buds on my red maples are swollen and ready to pop open. Last year these trees flowered on March 15, and it looks like they are right on schedule for that date this year. This morning I watched a red squirrel and then a much larger gray squirrel shinnying out on the thin, terminal branches of the maples to bite off the nutrient rich buds. The squirrels are getting a much appreciated, I am sure, fresh meal, and are also very effectively pruning the flowers out to the very delicate, very terminal branches of the trees.

My cat showed me another sign of spring yesterday afternoon. She was walking in tiny, mincing steps across the floor of the kitchen. Her body was tense and focused and her nose was almost touching the surface of the floor. She was stalking a tiny ant that had just made its late winter/early spring emergence from its overwintering nest probably out in one of our flower beds or under the concrete pieces of our sidewalks. These little ants (often called "sugar ants" but, probably more accurately called "pavement ants") are alien, invasive species from Europe that came to North America in the 17th and 18th Centuries in off-loaded ship ballast. They are interesting to watch (both for cats and biologists), but they can get too numerous and too persistent in their exploration of our floors, tables, and kitchen counters. Last year Deborah spread cinnamon at the ant entrances around our kitchen window and door and had very good success in discouraging their access to the house.
 
Arriving birds: A blackbird showed up this week around my front yard bird feeder. A few blackbirds come in every year and their arrival starts an annual field guide and internet search for what kind of blackbird it is. This one is too small for a grackle, not colored like a cowbird, and hasn't any bright red/orange shoulder epaulets of the red-winged blackbird.  I settled on the "rusty blackbird," but its eyes don't seem quite white enough for that. I will keep watching and thinking about it. Robins are abundant and common now. The male goldfinches are showing bright yellow colors. The male and female sharp-shinned hawks are perching noisily up in the black locust trees. There are flocks of bluebirds with incredibly showy males up in the local woods and also on campus. I haven't heard any more screech owls lately, but it is fun to listen for them. The tropical migrants (the grosbeaks and tanagers and the warblers) and the more local migrants (like the towhees) should all be showing up very soon.
 

Almost exactly two years ago I bought a bat house kit from the Organization for Bat Conservation and after a fairly painless assembly and painting process attached it 15 feet up the trunk of a tall spruce tree about 20 feet from my house. I oriented the bat house to catch as much of the morning sun as possible and hoped that it would be a well received resource for the local bat community. April and May 2010, though came and went without any bats showing up at my house. And, that's what happened in 2011, too. Both summers I heard bats flying past among my trees and over my deck through the early night hours gobbling up mosquitoes and other night-flying insects, but the bat house, for whatever reason, did not attract them.

I was hoping for a colony of pregnant females to come and set up a nursery roost there. A lactating female will consume over 100% of its 5 to 14 gram body weight each night in insects. They can eat up to 600 insects per hour, and a million bats will eat, according to the Wisconsin Bat Monitoring Program, 694 tons of insects in a year! That's a lot of mosquitoes that won't be able to bite us!

The bat I was hoping to welcome to my house is the little brown bat. This is the most common bat in Pennsylvania and has abundant hibernating sites nearby (caves and old coal mines). I have seen this species roosting under eaves of local outbuildings and up in the attics of several of our neighbors' houses. One summer a small group of little brown bats (probably males) even utilized the narrow spaces of the picnic pavilion roof supports out by the Campus Nature Trail for their day roost. This species does not appear to be picky about choosing its roosts, except when it came to my bat house!

I am looking out the window above my desk and am stunned by the browns and greens of my yard. There is no white to be seen, no snow.

I have friends who seem positively grateful that we have had so little snow this winter, but I am not one of them. I lived through too many "brown winters" in Texas to not be aware of the aesthetic beauty of a fresh snowfall. But, there are also some significant ecological benefits of snow.

For example, snow is an excellent insulator. A layer of snow will prevent the soil beneath it from freezing too deeply to the great benefit of the roots of many perennial plants. Also, the snow layer will buffer against the repetitive cycles of a soil's freezing and thawing that can "frost heave" shallow rooting plants right up out of the ground. The snow cover also generates an important crawl space and refuge for insects and small mammals just above the soil surface. This "subnivian space" is important for many winter active species and is described in an essay out on our Virtual Nature Trail.

The snow cover further benefits plants in two very significant ways. It represents a water reservoir that very slowly and very effectively delivers soil moisture to the early growing plants of the spring. The snow also contains a surprising amount of plant useable nitrogen that has been gathered from the atmosphere during the snowfalls. As the snow melts in the spring, this nitrogen is immediately available to the early sprouting plants and is very important in their growth.

So, snow Is a hassle sometimes. Our cars get stuck in it, shovelfuls get heavy and so on, but our gardens, yards, and wild places greatly benefit from its presence.
  
On a more "spring-like" topic: this morning I heard and this afternoon I saw my first robins of the season. These warm sunny days are drawing the flocks out of their relatively close winter hideouts and are stimulating them to spread out across the wet, earthworm rich yards and fields. This afternoon there were about a dozen robins spread out across my neighbor's yard. They cackled to each other as they hopped about one eye glued to the soil surface in front of them. It was not a good day to be an earthworm!

It did feel like spring while I was watching them!

Yesterday afternoon the sun warmed up my south-facing porch and the latest "sign of spring" emerged. Dozens of dark spotted, orange "ladybugs" crawled out from under the siding and warmed themselves in the welcome sunshine. These "ladybugs" (who are neither all female nor "bugs") are more appropriately called "ladybird beetles."  They are widely recognized as effective bio-control agents against aphids and scale insects and are one of the relatively few types of insects that overwinter as adults. Back in the late days of autumn these beetles found their ways into the tiny, protected spaces under the porch siding (and inside the garage and inside the house and under the loose bark of trees, etc.) and have been sleeping away the winter.

Most insects overwinter as cold resistant, relatively inactive eggs or pupae, but there are some distinct advantages along with some potentially fatal disadvantages to adult hibernation. The big advantage is that the spring emerging adult is all set to immediately respond to a warming trend and then go and disperse, gather food resources, and mate (eggs and pupae have a lot of growing to do before they are ready to go out and similarly "seize their days"). The overwintering adults, then, have first access to the abundant resources of the awakening spring world. Potential disadvantages include the hibernating adult life stage's vulnerability to both predation (all winter many birds like the chickadee constantly work their beaks into any tiny space looking for hibernating insects) and metabolic exhaustion while they are in their hibernaculae (stored body energy must be used to keep the large, complex adult form alive even in its quiescent state). Further, the adult may emerge too early in the season and get fatally caught out in the open in the sudden return of winter conditions.

So it's a balance between the competition for being first and the safety of waiting until a seasonal "all clear" has been sounded. The ladybird beetles have evolved the strategy of being first.

One of the first signs of spring that break through the short days and long, cold nights of January is the unmistakable and overwhelming olfactory blast of skunk. Male skunks have started to wander about at night in search of females. They cruise through yards and grab snacks under birdfeeders or in easily overturned trash cans. They also stray onto area roadways and represent a high proportion of fresh road kills.

Many animals are initiating their mating behaviors. Gray squirrels are chasing each other up and down the maple trees in my back yard. I saw one actually climbing along on the underside of a high, vertical limb in an attempt to sneak up on the object of his affection. The young from these matings will be the "winter born" litter that we will watch grow throughout the summer.  If food is abundant enough the squirrels will have a second "summer born" litter in July that will mature just in time for next fall's acorn season.

I have gone out at night and listened for great horned owls, but I have yet to find one. I always look across the black outlines of the upper tree branches hoping to see their silhouettes against the pale, cloudy sky.  Great horned owls start calling to their mates as early as late October and are one of the earliest mating avian species in North America. Mating typically occurs in January or February with the owlets hatching in the late winter or early spring. Nesting sites are whatever is available: old crow or hawk nests, squirrel nests or tree holes, caves, or even human-made shelters. These owls may be taking advantage of the wandering skunks, too. They are one of the few predators that are willing to take skunks as prey.

Another significant predator of skunks are coyotes, and we are also at a time of great activity for them. Like the skunks, the coyotes are wandering about looking for mates. People should be cautioned to keep pet cats and dogs in at night to keep them from being eaten by the active coyotes. House cats are a perfectly sized prey species for a coyote.  I saw a coyote one night two weeks ago crossing an open field in Plum and another one some months ago out in a similar habitat in Kiski Township. They are abundant in almost every rural and urban region of the country. They are close by, active, and work very hard at not to being seen by people.

So some thoughts and sights of spring! Love is in the air. So, when do we get some snow?