Field & Street | Field & Street | Chicago Reader

Field & Street 

Sign up for our newsletters Subscribe

After months of effort, Bill Valentine and I have finally finalized a final report on the nesting birds of Somme Woods, 1992. I had the help of a computer, but Bill compiled his part by paging through a stack of spiral-bound notebooks and rearranging three months' worth of sightings into a species-by-species account, using no weapon stronger than a ballpoint pen.

Somme Woods is a Cook County forest preserve in Northbrook where work has been continuing for the past 15 years on a restoration project that aims at recreating the native prairie and oak savanna vegetation that grew there prior to European settlement. Our surveys of nesting birds are designed, among other things, to help us measure the effect of the restoration work on bird populations.

Our final report says that we confirmed nesting by 30 species of birds at Somme in 1992. And we had another ten that we could classify as probable nesters, for a total of 40. Last year, our confirmed and probable lists totaled 31. Of the additions, seven were species present last year that we couldn't confirm until this year. Two, the blue-gray gnatcatcher and the wood thrush, were new this year.

The contenders in the category of Most Common Bird, were the American robin, red-winged blackbird, song sparrow, and gray catbird. The catbirds and song sparrows were tied at 20 pairs apiece. The robins and redwings more or less overwhelmed our counting ability. Robins are present in noticeable numbers virtually everywhere on the preserve. They nest in dense woods, in open oak groves, and in isolated trees out on the prairie. I found five nests in late April and another six in June. Bill located 15 others of various dates. Redwinged blackbirds make things difficult for counters by being polygynous. A single singing male may be presiding over three females, each with her separate nest. We can say with reasonable assurance that both of these species are more common than catbirds and song sparrows, but we can't provide any solid numbers.

Three pairs of brown thrashers--close relatives of catbirds--nested this year. The males favor trees or very tall shrubs for singing perches, and their territories were all along the edges of our patches of woods. Catbirds often live in low brush well away from trees. The males sing from hidden perches inside the thicket.

Somme Woods ought to be paradise for woodpeckers. As part of the effort to restore the native prairie and savanna vegetation, large numbers of invasive trees have been girdled. The girdling kills the trees but leaves them standing. These standing dead trees are loaded with both beetle grubs and nesting sites.

We had three species this year. One, or possibly two, pairs of hairy woodpeckers nested in our woods. A nest was attacked by starlings on May 6, but either they tried again or another pair moved in, because on June 19, Bill discovered a new nest. He could hear nestlings calling from inside the nest hole.

We were able to confirm six pairs of nesting downy woodpeckers, and we may have had more.

Our most common woodpecker was the northern flicker, with 12 pairs confirmed. We found nests in many situations: in dense woods along the river, in old oak groves, and in standing dead trees surrounded by prairie. The flicker would have been an ideal bird for the oak savannas that covered a substantial amount of presettlement Illinois. These birds nest in trees, but they often feed on the ground. Like robins, they are highly attracted to newly burned land. The bare land offers insects little cover, and that creates a bonanza for the birds.

The most common hole-nesting birds other than woodpeckers were black-capped chickadees, with 15 nests confirmed, and house wrens, with an estimated nine pairs. We found chickadee nests in dense woods, at the edge of an oak grove, and in a clump of dead trees surrounded by prairie. House wrens appeared in many of the same sorts of places. The most important factor for the wrens--aside from a suitable nest tree--was a dense understory of brush.

One of our new species, the blue-gray gnatcatcher, nested in a hawthorn shrub at the edge of an area where clusters of standing dead trees were surrounded by young trees or tall shrubs. The understory was dense brush in some parts--dogwood resprouts and briars--and grassy in other parts.

The wood thrushes nested in dense woods in the western half of the preserve. This species was one of 11 Neotropical migrants nesting at Somme. Ornithologists are worried about the futures of almost all the birds that nest in North America but spend their winters in Mexico, the Caribbean, and Central and South America. Major loss of habitat on the wintering ground, combined with loss of nesting territory here, has created alarming declines in many species.

Aside from the wood thrush, Somme's Neotropical migrants include one vireo, (the red-eyed), three wood warblers (common yellowthroat and yellow- and blue-winged warblers), three flycatchers (eastern kingbird, great-crested flycatcher, and eastern wood-pewee), the northern oriole, the indigo bunting, and the rose-breasted grosbeak. Some gray catbirds and blue-gray gnatcatchers migrate to the tropics, but some also winter in the southern United States.

Yellow warblers were the most common wood warblers at Somme. We figure that nine or ten pairs nested. We had seven pairs of yellowthroats and only one blue-winged warbler. We estimate six pairs of northern orioles nested. Red-eyed vireos made the list because we had at least three males singing, for two weeks or more in various patches of woods.

The great-crested was our most common flycatcher, with as many as five pairs. We found one nest at the edge of the large oak grove we call Vestal Grove. We had two singing male wood-pewees, one in Vestal Grove and one in denser woods along the river. The lone pair of kingbirds nested in tall trees at the edge of our largest prairie.

We had several sightings of a singing male willow flycatcher, but it never stayed in one place long enough to suggest that it was settling down. The favored habitat seemed to be low shrubs bordering wet areas. One such spot is along the stretch of low, wet ground we call Middle Swale.

We've got lots of bright-colored finches. With 16 nesting pairs, northern cardinals finished right behind the leaders in the abundance race. This is another species that likes brush. It nests in wooded areas where there is a brushy understory, along woodland edges, and in patches of brush some distance from trees.

We confirmed one nesting pair of rose-breasted grosbeaks and have two others fisted as probable. We could have as many as 11 pairs of indigo buntings and probably somewhat more pairs of American goldfinches. The buntings build their nests in low brush, but the males like to sing from the tops of the tallest trees, so they tend to concentrate along woodland edges. Goldfinches seem to like small hawthorns--down to three or four feet tall--and other upright shrubs. We find their nests in such situations, either at woodland edges or where isolated shrubs are well out on the prairie.

We also had one singing male rufous-sided towhee and one singing male field sparrow, both in a savanna landscape of grasses and scattered trees.

Another seed-eater, the mourning dove, was represented by at least six pairs at Somme. I am not happy with that number. I think there were more mourning doves than that. I am hoping that this year we will get a better handle on their numbers.

Cedar waxwings are a nomadic species. They travel in flocks and they often nest in concentrations that approach the density of colonies. This year, one of those concentrations showed up at Somme. In an area of standing dead trees and flourishing brush, we found five nests in an area less than 150 meters square.

We found five crows' nests at Somme last year. And our estimates suggest that as many as 15 pairs of blue jays nested.

We had a few sightings of Eastern bluebird in 1992, including one of a pair together that allows us to list this species as a probable nester. However, I don't think they actually did nest.

Brown-headed cowbirds are very common at Somme. Cowbirds are brood parasites. They lay their eggs in the nests of other species, the unwitting foster parents with the job of raising cowbird young. Thus for, we have evidence at Somme of cowbirds laying their eggs in the nests of yellow warblers, indigo buntings, gray catbirds, and red-winged blackbirds. I expect to be adding species to this list in future years.

We had two raptors. Red-tailed hawks again occupied the nest they had used in 1991. They fledged one young bird in '91, but this year they were unsuccessful. They abandoned the nest in early May. The American kestrel was present last year, but this year Bev Hansen and Bill saw a pair copulating, and that lets us list it as a probable nester.

Six male woodcocks were displaying during early spring evenings, and we found one nest--with three eggs--of this species. A mallard hatched 14 young in the pond we call the Prairie Pothole. Common grackles were around and may have nested on the preserve. And we had three clusters of starling nests. This alien is ideally adapted to savanna conditions, so, like it or not, we can expect it to be a part of our savanna restorations.

With 1992 at last out of the way, I can start getting ready for 1993. The woodcocks will be displaying at Somme just a month from now.

Comments

Subscribe to this thread:

Add a comment

More by Jerry Sullivan

  • Vote Kestrel!

    Neither waxwing, nor kingbird, the best candidate for official bird of Chicago is right under our noses.
    • Oct 7, 1999
  • Field & Street

    • Feb 4, 1999
  • Field & Street

    • Jan 7, 1999
  • More »

Agenda Teaser

Performing Arts
Guards at the Taj Steppenwolf Theatre
June 13
Performing Arts
June 21

Tabbed Event Search

Popular Stories