April 26, 2016 at 6:02 am (geology)
Tags: continental glacier, gneiss, Lake Michigan lobe, St. James Farm
by Carl Strang
St. James Farm Forest Preserve has a scattering of stones, large and small, in its forests and open areas. Some of these are chunks of local Silurian dolomite bedrock that were gouged out by the most recent continental glacier. Others are glacial erratics, stones likewise left by the glacier but picked up by it where the bedrock was different. These generally source back to Canada. Though much of the glacier’s Lake Michigan Lobe route followed that lake bed, the bedrock there is a soft shale that the ice ground to clay, with occasional surviving pieces up to a couple inches across, but nothing that could be called a boulder.
Recently my eye was caught by a trailside erratic split by the temperature changes that the seasons bring.
This appears to be a rock type known as gneiss, which started out as granite but was subjected to stresses that altered its structure into a banded pattern. Such bedrock is common around the east end of Lake Superior, where our glacial lobe exited Canada.
There was no indication that the rock had been struck by anything to create the break. Freezing and thawing were sufficient. I photographed the rock and left it as is. A week later, passing that way again, I saw that someone had replaced the fragment.
Gravity works, and the pieces were fitted precisely, so a human agent is indicated.
So, what motivation are we tracking here? Was it simply a matter of orderliness? Or, did someone want to make sure that the fragment did not become someone’s souvenir? Or, was this putting-back-together an act of kindness to the rock? I am reminded of one of the most widespread traditional stories west of the Mississippi River, with every Native American tribe having at least one version, in which an animated rock teaches Coyote (or his trickster equivalent, depending on the version) a lesson of respect.
April 23, 2016 at 6:06 am (birds)
Tags: Canada goose, Cooper's hawk, eastern bluebird, eastern phoebe, great horned owl, hooded merganser, nest, northern cardinal, red-tailed hawk, song sparrow, St. James Farm, yellow-rumped warbler
by Carl Strang
Soon the first wave of birds that overwintered in the tropics will reach northern Illinois. April has brought a transition from wintry weather to the warmth, plant growth and insects that make the trip worthwhile for the many species whose ancestors were content with tropical conditions.
For most of the month we see birds that are year-round residents or are newly arrived from their wintering grounds in the southern states. They have to deal with the season’s variability, though. Early in April a cold spell brought a thin snowfall. There still were insects to be found, but they were on or close to the ground. A selection of species foraged on the banks of the stream at St. James Farm Forest Preserve.
These included an eastern bluebird that abandoned his practice of hunting from tree branches, and shifted to hopping around in the open.
The preserve’s first yellow-rumped warbler of the year also searched for prey there, though such bank foraging is a common practice for that versatile species.
Even an eastern phoebe was forced to a ground-foraging interval.
On other days, getting set for the nesting season was a priority.
Cooper’s hawks occasionally called in wooded areas, considering whether to nest at St. James Farm.
Song sparrows sang as they began to sort out their territories.
Cardinals have been singing since January, as they are the songbirds most sensitive to day length change.
Pairs of hooded mergansers hung out on ponds where there are nest boxes.
The preserve’s red-tailed hawks completed their nest and were good to go.
A second pair of geese chose St. James Farm for nesting, but their site is a risky ridge beside the stream, with water on each side but reachable from either end by a coyote.
April 21 was warm enough that the great horned owl young did not need brooding. This was my first look, and I could not be certain there was more than one baby.
And now, with the warm days forecast ahead, the big push of migrants soon will diversify the preserve’s avian picture.
April 21, 2016 at 5:34 am (singing insects)
Tags: Chortophaga viridifasciata, green-striped grasshopper
by Carl Strang
There have been several early season warm periods this year, allowing the greening of food plants and the higher temperatures that support invertebrate growth. I have anticipated that this might be a relatively early year for the first sound displays by green-striped grasshoppers, and that expectation was realized on Monday when I heard the fluttering buzz of a flying male, and got a glimpse of him as he landed.
Male green-striped grasshopper photographed in an earlier year.
This was the second-earliest date in 11 years of observations, and was 15 days ahead of the median first display date. As you walk though areas with unmowed grassy growth, listen for a soft buzzing sound. This is the controlled rattling of wings by a grasshopper at the end of a display flight. With some luck you may catch the insect’s motion and get a look at one.
April 4, 2016 at 6:21 am (birds, botany, mammals, plant-eating insects, reptiles and amphibians)
Tags: Acer saccharinum, barred owl, brown-headed cowbird, bullfrog, cabbage white, Canada goose, Claytonia virginica, golden-crowned kinglet, great horned owl, green-winged teal, hooded merganser, killdeer, midland brown snake, midland painted turtle, mourning cloak, northern flicker, Nymphalis antiopa, Pelochrista, Pieris rapae, pileated woodpecker, preserve monitoring, sandhill crane, silver maple, spring beauty, St. James Farm, western chorus frog, whitetail deer, wood duck
by Carl Strang
Weather in March at St. James Farm Forest Preserve was variable, but on the whole was relatively warm with frequent rainy periods. At the beginning of the month there was a little lingering snow on the ground, and ponds were frozen, but all of this quickly was gone.
I used my old GPS unit to map my survey routes and to locate positions of previously discovered cavity trees that might harbor a great horned owl nest. One of these indeed proved to hold the nest, and the female still was present on March 25, late enough to indicate that hatched young were being brooded. Two attempts to find displaying woodcocks were unsuccessful, but during the first evening visit on March 17 I heard what I thought was a short call by a barred owl in the eastern portion of the preserve. Scott Meister reported hearing the species in the forest one evening the following week. No pileated woodpecker observations in March, but recent observations in preserves to the north along the West Branch suggest that the bird or birds seen here earlier may be wandering widely. Canada geese were down to small groups and pairs early in the month. By March 31 a nest was under incubation on the small island in the pond below the former house site.
Canada goose incubating on March 31.
Many killdeers were displaying in the restoration project area around the stream early in the month, but these were down to just a few individuals by month’s end. Bird activity generally increased as the season progressed, with the first cowbirds arriving March 8, a pair of hooded mergansers and 2 pairs of wood ducks present in the pond in the NW corner of the preserve for much of the month, sandhill crane flocks frequently passing overhead, a northern flicker and the first golden-crowned kinglets appearing on March 14, tree swallows on March 25, and two pairs of green-winged teals in the restored stream on March 26.
This hooded merganser pair may nest in one of the wood duck boxes at the northwest pond.
A shed antler found on March 17 in the forest near Winfield Road matched the buck photographed in the same area on November 1.
Someone found an old deer skull and propped it against a trailside tree.
The first snake observed on the preserve was a midland brown snake on March 29. That same day several painted turtles were sunning in the eastern pond.
Western chorus frogs began singing on March 11, and ultimately displayed in three locations. The largest number were in the fringes of the eastern pond, and many also were in two temporary ponds in the meadow north of the entrance drive. Numbers of bullfrogs, large and small, had emerged by March 21.
One of the March 21 bullfrogs.
The first butterfly of the year was a mourning cloak observed on March 21. A cabbage white appeared on March 29. The former overwinters in the adult form, the latter as a pupa. Several small brown moths were active on the forest floor on March 31. One was photographed and appears to be a tortricid, close to several similar species of Pelochrista or perhaps Eucosma.
A possible Pelochrista
Silver maples were blooming by March 11, and spring beauties by March 31.
Spring beauties were the first native herbaceous wildflowers to bloom at St. James Farm in 2016.
Restoration clearing of the forest was completed by mid-March, and a new set of stakes presumably marking the new trail route was placed in the final week.