The birds are beginning to settle down at Somme Woods. Somme is the Cook County forest preserve in Northbrook where I have been working with three other volunteers on a survey of nesting birds.
We have always had the much-despised European starling, an alien species, nesting at Somme, but this year starlings are moving into parts of the preserve where they had not nested before. Starlings are hole nesters, and one of the reasons bird lovers don’t like having them around is that they are very aggressive in going after choice nest sites, often driving away native birds. So far this year we know of one pair of flickers evicted from a nest hole by starlings, and Bill Valentine and Bev Hansen, two fellow volunteers, saw starlings driving our only known pair of hairy woodpeckers out of their nesting hole.
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May brings the final wave of our nesting population. The migrants that wintered in the tropics arrive just as the opening leaves trigger the hatching of spring’s first crop of caterpillars. We now have house wrens singing furiously. I have heard the wheezy, flatulent, two-note song of the blue-winged warbler. Yellow warblers and yellowthroats are singing in the brush, indigo buntings from the treetops. A wood pewee is once again singing from the lower branches of the oaks in Vestal Grove. Northern orioles are building nests.
Later in the season the robins will build higher up in the trees. But the first nests of the year are built before the leaves emerge–we found our first on April 22–and standing trees provide almost no cover. The birds–and this seems typical of many species–build their nests well before they are ready to lay eggs. The nest may sit empty for a week or two before laying begins.
Kestrels are not much bigger than robins, so they cannot take the larger birds that peregrines specialize in–chickadees and goldfinches are as big as they can handle. They also eat mice and other small mammals and lots of insects.
Nighthawks don’t really build a nest. They just find a piece of ground that is to their liking and lay their eggs on it. During the day they sit very still, and their mottled brown plumage camouflages them very effectively.
