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.
My inability to find nests fed my deepest anxiety: that I am an impostor. Certainly a big-time environmental/nature columnist shouldn’t need a week to find a miserable robin’s nest. I affected an air of confidence, but I knew nest finding was like whistling with your fingers in your mouth or computer programming, a skill you either picked up in childhood or never got at all.
But that was before the day I found the frame of an Acadian flycatcher’s nest slung between the tines of a tree fork and watched the female adding stems to a foundation that looked as flimsy as a spider web. And that was before the day the Carolina wren with a grass stem in her beak crawled into a hole in the side of a hummock of moss and revealed where her nest would be.
I saw these things in the Shawnee National Forest near Jonesboro in deepest southern Illinois. The birds live in Trail O’ Tears State Forest and the LaRue-Pine Hills Ecological Area, both within the boundaries of the Shawnee and both among the largest remaining blocks of forest in Illinois.
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.
Dr. Robinson has a small army of graduate students–along with a few undergraduates–scouring the woods every day. They search for nests, and many of them are very good at it. Robinson sent me out three different days with three different guides. Doug Robinson, Lonny Morse, and Rob Olendorf are all graduate students at Champaign who did learn to find nests when they were kids, and their work was wonderfully enlightening.
Forests are especially hard places to do nesting studies. The birds are spread out. You can’t see far. Some of the most important species nest high in the canopy. But Robinson’s army is piling up the data in spite of these obstacles, collecting information on cowbird parasitism, predation, year-to-year population levels, habitat choice, and the numbers of fledged young that return to their native woods the following spring.
All this starts with finding nests, a job that isn’t easy, even for the experts. The average rate for nest finding among Robinson’s skilled workers is one nest for every two hours in the field. It’s a job that takes a fairly advanced level of patience. You have to sit for long periods waiting for something to happen, and you have no guarantee that anything will.
In most cases the male is the starting point in the search. He is singing, often from an exposed perch, so he is easy to find. But once you find him, you may think that you haven’t really found much. Males sing on their territory, but in most species they stay about as far from their nest as they can manage.
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.
Once you have figured out the approximate shape and location of the territory, the real waiting begins. If the bird’s territory is uniform habitat, all woods or all grassland, you can start a very slow stroll through it looking for some sign of the female. If it is a mixture, if it includes both woods and prairie, you look only in the parts where your particular quarry is likely to be. Most birds with a mixture of woods and prairie in their territory are edge species, and you can find them gathered within a few yards either way of the boundary where forest meets prairie.
When you have figured these things out, you find a likely observation post and sit down to wait. You are waiting for some kind of break, for a clue that will help you get closer to the nest. The clue may be the female with a grass stem in her beak. It may be the male with a caterpillar in his beak taking food to the female on the nest. It may be both parents carrying food to young in the nest. It may be the female taking a break from incubating eggs and moving around the territory feeding. In many species the males accompany the females on these outings.
Working on this year’s edition of my Somme Woods breeding bird survey, I have tried to apply what I learned in the Shawnee–and to my surprise, it has worked. After eight visits spread over two weeks I have found 35 nests belonging to 17 different species.
This sudden leap into competence is totally amazing. The veil has been lifted. The most secret aspects of these birds’ lives have been suddenly revealed to me. In this one small corner of the world I know more or less what is going on. And that is a claim I cannot make about any other part of my life.
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.
And then a hard one. Close to an hour spent mostly on hands and knees studying a thicket that eventually got me my first song sparrow nest. My first catbird nest came while I was searching for a second song sparrow nest. I’ve found five red-winged blackbird nests. These are easy. The males are so eager and noisy in their defense of the nest that they lead you right to it. I found my first yellow warbler nest after watching a pair of the birds flying together around their territory for about 20 minutes. She mainly led the way, and every time she flew to a new branch, he would follow. I lost sight of them briefly, but by and by he appeared on a bare branch in a tall snag. He seemed to have a caterpillar, or something like it, in his beak. He dropped straight down into the dense thicket of shrubs at the base of the snag. When I went to that place, I found the nest. It had three yellow warbler eggs and one brown-headed cowbird egg left for the warblers to care for.
Sitting down and shutting up turns out to be the secret of nest finding. It’s a learnable skill. You don’t need to remain motionless for an hour at a time, but you shouldn’t move without good reason, and you should move slowly and quietly. Stay reasonably quiet and still for an hour, and nature will start to show you things. I was sitting watching a blue-winged warbler, hoping to locate its nest, when a pair of bluebirds began inspecting an old woodpecker hole in a tree stub 30 yards away. A house wren flew up singing, contesting their control of this nesting hole. He stormed about the place for several minutes, while the bluebirds sat, silent and unmoving, between him and the hole, showing what animals that are really good at holding still can accomplish. Out of the corner of my eye I saw a chickadee slipping through a tiny hole into a nesting cavity in a tree stub no more than a foot tall.
While watching a pair of yellow warblers feeding together, I saw a northern oriole perched in a tree above me and in the next tree his mate about to enter her nest. Watching an indigo bunting, I saw a field sparrow carrying blades of grass to a tangle of low shrubs.
The blue-winged warbler was the best so far. I spent over two hours hanging around one little patch of ground watching and listening to the male, but I knew that my chances of finding the nest were slim. Blue-wings nest down in the brush where things are dense, and their nests are only three or four inches across.
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.