Closer look at my phoebe babies
Almost two weeks after hatching, the four nestlings in my eastern phoebe brood have pretty much filled up their nest and seem to be in danger of falling over the side. I say “my” phoebes because, like most people living in the country, I usually have a pair of phoebes nesting somewhere under the eaves of the house.
Seeing them every day, from the time they start arriving in the spring until they leave for the winter, and watching them raise their families, it’s easy to develop a proprietary interest, and I’m not alone. I often talk with other phoebe landlords about our respective phoebe families— where they choose to nest, the development of their young, and their loud, seemingly incessant “fee-bee” call that trumps the alarm clock in waking us up at dawn.
Having figured out as a species long ago that we and our structures offer protection from the weather and predators as well as provide invertebrate prey that is also attracted to buildings, phoebes have formed an unofficial alliance with us. While many prey animals have learned to pay attention to predators watching them and flee or freeze, as appropriate, phoebes generally adjust to our presence and even our stares, especially if we don’t bother them. I could walk within a foot of the security light over which one pair had nested without disturbing the mom on the nest, even when I stared at and talked to her.
However, when the current phoebe mom sees me looking at her, she immediately dives down out of the nest and takes the typical vertical “u” turn when coming to or leaving the nest, lessening their profile against the sky and otherwise trying to slip by any predators in the area. Males don’t bother with such deception, going back and forth in a straight line, perhaps because they don’t spend time at the nest except to feed the young and therefore are much less likely to attract a predator’s attention.
The eastern phoebe ( Sayornis phoebe) is in the Tyrant Flycatcher bird family, which preys mostly on flying insects. Normally the phoebes provide endless shows of aerial acrobatics – flying straight up helicopter style or bee-lining straight ahead to grab some unsuspecting insect out of the air. However, when their young hatch out, their hunting tactics shift, as I learned from a great series of books on bird behavior, the Stokes Nature Guides’ three-volume set, “A Guide to Bird Behavior.” When they have young to feed, phoebe parents start diving after prey on the ground. Why? It must have something to do with the type of insects they want to feed their babies, but I haven’t been able to find an explanation, even in the Stokes guides.
One of the greatest threats phoebes face in reproducing are mites that infest the nest and drive the young out. I’ve seen two clutches meet this unhappy fate, so I always clear away the current phoebe nest once the babies have fledged. It may take the mom some effort to build another one, but the brood she’ll put into it represents a much more significant investment in time and energy. Phoebe females often build more nests than they’re going to use anyway.
The other main threat to phoebes’ reproductive success is cowbirds, whose own strategy is to lay one large egg in a smaller species’ nest. The cowbird baby is larger and grows faster than the hosts’ babies, and eventually either shoves them out of the nest or just outcompetes for the food the adults bring, leaving the babies to starve. It’s estimated, depending on the source of the data, that from 25 to 75 percent of phoebe nests are parasitized this way.
Phoebes typically nest on any structure jutting out under eaves of a building or is otherwise sheltered. Their nests are “well constructed of weeds, grasses, fibers, mud [and] covered with mosses, lined with finer grasses and hair,” according to Peterson’s “A Field Guide to Birds’ Nests.” An experienced female phoebe will usually construct the nest to make the rim level, no matter what it’s perched on. My female phoebe picked a fan outtake, which is slanted, and built a nest that is a bit shallow and follows the slant rather than being level at the rim. This may indicate she is less experienced, or just not very good at nest building.
The phoebe parents typically use my laundry or telephone lines to scope out their prey, undoubtedly because the wires offer an unobstructed view of the house, yard, and surrounding forest edge, where they prefer to hunt. A tall, double-hooked plant hanger I stuck in my compost pile above several huge volunteer squash plants has now become a favorite perch as well. I hung a large ship’s-bell windchime from one hook and a hummingbird feeder from the other.
The phoebes spend a lot of time perching on the bow of the taller hook, launching themselves from time to time at bugs working the squash blossoms and compost heap below. The arrangement benefits both of us—fewer bugs to eat the squash, so more squash for me, and the phoebes get easy access to food for their young. The hummers and phoebes mostly ignore each other, so everyone should be happy.
The current phoebe brood is likely the second one for this pair this year, who could have up to three. The nestlings should leave the nest in the next week but continue to stay close and be fed by the parents for several more weeks. According to the Stokes guide, the male ends up doing most of the feeding at this point while the female gets started on the next brood. If fledglings don’t leave the area within three weeks, the parents will likely drive them off.
Check out the slideshow on the author’s blog at wildideasintheblueridge.blogspot.com.