The nesting season is in full swing, and with it comes some pretty interesting reports. From birds using funky material for a nest to choosing an odd location, there never seems to be a shortage of novel (at least to me) behaviors reported to Maine Audubon each year.

One interesting case comes from reader Elisabeth Webster in Bowdoinham, who has been hosting eastern phoebes nesting on the porch for the past nine summers. Eastern phoebes are especially well known for nesting on man-made structures, especially the edges of porches or underneath bridges; kiosks and gazebos are also commonly used. Their muddy bottomed, moss rimmed and stick-lined nests are fairly distinct, but the eventual mess from well-fed babies are what most hosts contend with. The unique thing about these phoebes this year was that they built two nests.

It isn’t uncommon for a bird to start building multiple nests, often testing different sites before finding the one that will be most suitable. Some species, like male Northern House Wrens, will move into an area and make as many nests as possible to claim the spots until a female shows up. These wrens are cavity nesters and will fill any hole they find with a bunch of sticks, often called a “dummy nest.” Then, when a female arrives, she’ll pick which site to use, and together they construct the actual nest she’ll lay eggs in. With phoebes, only the female builds the nest, so the location and construction are all up to her.

During this wet spring we’ve had, it seems many early nest attempts were abandoned and birds started over. What is very uncommon about these phoebes is that they built two nests, and then laid eggs in both. Phoebes can nest in pretty close proximity to each other, but the reader carefully watched these nests and noticed it was just the one female incubating at both nests. This was a first for me.

Digging around in the literature, I did find a similar occurrence from 1962 in New Haven, Connecticut, written up in The Wilson Bulletin (September 1968) of a phoebe using two nests. This bird was nesting under a bridge and built two nests on either side of a junction of girders. Phoebes typically lay five eggs in a single clutch, and the observers noted three eggs in one nest and two in the other. Over the course of a couple of weeks, the incubating female would spend time on both nests, ultimately favoring the one with three eggs. Eventually, the nest with two eggs failed, while two of the three eggs in the nest getting more attention did hatch. The authors hypothesized that the bird might have accidentally been using the two sites because of confusion by the similarities based on the orientation of their approach. The girders looked so similar, so if the bird was approaching from the north, it would end up at one nest, and from the south, it’d find the other.

These Maine phoebe nests, on the other hand, are only a couple feet away from each other, but both are built in the same orientation at different corners where a rafter and top plate come together. The phoebe has split the clutch, with two eggs in one nest and three in the other. We are often told we decrease our risk by diversifying, and “not putting all of our eggs in one basket” but unfortunately for these phoebes, that won’t be the best method of fledging all their young. A single nest requires so much time incubating that splitting that effort, sadly, is almost certain to fail.

At this Bowdoinham site, the female stopped sitting on eggs in one nest, and the eggs in the other nest have hatched and are being fed.

We’ve still got a couple months of nesting left this season. Some species will be starting a second brood soon, while many seem to be delayed with the cold and wet spring we had. Keep those birds in mind whether you are walking the beach (watch out for nesting piping plovers) or doing yard work. Delay mowing fields until late July if you can to help nesting grassland birds, and we can all shop around for native plants to make sure birds are finding the right food they need to feed their young.

Have you got a nature or wildlife question of your own? It doesn’t have to be about birds! Email questions to [email protected] and visit www.maineaudubon.org to learn more about birding, native plants, and programs and events focusing on Maine wildlife and habitat. Maine Audubon Staff Naturalist Doug Hitchcox and other naturalists lead free bird walks on Thursday mornings starting at 7 a.m., at Maine Audubon’s Gilsland Farm Audubon Sanctuary in Falmouth.