Give birds enough time, and they will show you their nests. In years past I couldn’t fully appreciate this truth because I didn’t know how to approach the birds, how to persuade them to reveal their secrets. Looking back I realize that what I thought of as nest hunting was really mostly random wandering and aimless staring. I may have thought I was searching diligently, but mostly I was standing around hoping a bird would walk by carrying a nest. My results showed it. When I tried to survey nesting birds at Somme Woods in Northbrook last year, the few nests I did find were pure accidents. Mostly I confirmed nesting by sighting awkward little stubby-tailed fledglings. Since they obviously couldn’t fly very far, I could conclude that their former nests must be somewhere nearby.
I was there to learn about Scott Robinson’s studies of the nesting success of neotropical migrant forest-interior birds. That string of adjectives specifies that we are talking about birds that nest in southern Illinois, spend their winters in the tropics, and live not along the edges but in the deep shade in the heart of the forest. Prominent species include wood thrushes, hooded warblers, cerulean warblers, scarlet and summer tanagers, and Kentucky warblers.
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If you find a male, watch him. He will move around his territory, singing from different song perches. Noting the location of those perches, you can get a rough idea of the shape of the territory. Somewhere in that territory is a female and a nest–unless the male hasn’t found a mate and is singing to attract one.
My first find was a northern oriole. This one was a gimme. I looked up into a treetop and saw a male northern oriole. I glanced into the tree next to his, and there was the nest hanging on a branch about 20 feet up.
But I watched and listened and sat still until the male landed on one of his singing perches with a caterpillar in his beak. This was the break I needed. I watched him fly into a narrow strip of trees and brush and then walked to a place about 20 yards from the strip and sat down to watch. Presently he flew up from the base of a tall tree. I figured he had just fed the female on the nest, and since I didn’t have a very clear idea of where he had been down in the brush around the tree, I waited. After about 15 minutes he was back. I saw him emerge from the brush a few yards from the tree. I walked over and started to search. The vegetation was resprouts of buckthorn and other shrubs that had been cut by work crews from the North Branch Prairie Project. The resprouts were only about knee-high, but they were quite dense. I saw a flash of movement in the brush. It was the female leaving the nest. Just under the crown of leaves of a buckthorn sprout, I saw a few brown dead leaves. I remembered that the field guides said that blue-winged warblers use dead leaves as a foundation for their nests. I parted the crown of live leaves, and there was the nest. Three tiny eggs no more than three-fourths of an inch long were inside. I took a good look at them and then got the hell out so the birds could get back to their parental duties. I danced down the trail back to my car.
