When a tuliptree that endangered my landlords house was taken down recently, my landlady found a nest among the fallen branches and brought it to me for identification, as she and her husband often do when they find such natural treasures.
The nest was empty, but likely not because of the fall. At this time of year, most songbirds here are through with reproduction. Although I was determined to try to find more bird nests this year, to get better at identification, My nest-ID skills are minimal, so as usual, I turned to my go-to book for that task, “A Field Guide to Birds’ Nests in the United States East of the Mississippi River,” a Peterson Field Guide.
The nest offered a lot of interesting clues, starting with its size and shape: small (about 2 inches across), with thin walls, deeply cup-shaped and hung from the fork of the branch. That last clue was the one that stood out — while many birds attach their nests to the top of limbs, few hang them from limbs. With these clues in mind, I went straight to the songbird section of the guide.
There I looked for the other more-obvious clues the found nest offered: The outside was covered with what looked like bits of white paper, with white strands securing the nest to the branch, along with strips of bark. Touching the white stuff, I found it sticky, helping to confirm my first guess, that it was spider silk, but globs of some other white substance was mixed in.
Finding a photo and description of a nest in the guide that matched the one in hand, I deduced the found nest was that of a red-eyed vireo. Although other vireo species build somewhat similar nests, their nests have thicker walls. And I had been observing several red-eyed vireos in the vicinity for most of the breeding season but had observed only one other species in the same genus, a warbling vireo that stopped by briefly one day and then moved on.
Going back to the question of what the white globs in what I was now sure was spider silk, the Peterson guide does include paper among the possible construction materials for the red-eyed vireo’s nest. But the guide also says the nest is “covered on the outside with spider webbing” and “decorated externally with lichens.” AllAboutBirds.org adds that the female, who builds the nest, “glues the materials (some of which are provided by the male) together and to the branch fork with spider-web adhesive, occasionally supplemented with spider egg cases and sticky plant fibers.”
Red-eyed vireos nest in a variety of deciduous trees, including tuliptrees, so its original location also fit. I had no idea how far up this nest had been before the branch it was on was cut off, but the Peterson guide says they are usually built about 15 feet up. Although I hadn’t noticed any vireos in this specific tree, I hadn’t spent much time observing it. Adults rarely vocalize or hunt near their nests, to avoid drawing a predator’s attention to it, so I would likely not have noticed any nesting there without careful surveillance. Throughout the breeding season, I had observed at least one red-eyed vireo several times a day in the copse near my deck, which is only a few yards from the tree.
The nest also could have been built in a previous year, although it looked new. In looking at other photos of red-eyed vireo nests online, I found they varied quite a bit, but the basic materials and location matched the one in question, so I’m comfortable with its identification.
Identifying the nest led identifying a cracked, empty eggshell that had been found a few yards from the tree several years ago. The photo and description of red-eyed vireo eggs in the Peterson guide matched the notes and photos I had taken of the eggshell at the time: tiny (three-quarters inch long by a half inch wide), with unevenly distributed small, brown spots. The same pair of vireos that built the nest could have produced the egg. I hoped they had successfully raised a brood and would return next year to raise another.
© 2019 Pam Owen