Great Crested Flycatcher

The Great Crested Flycatcher is the only flycatcher in New Hampshire that nests in cavities. These are usually old woodpecker holes or natural knotholes, but the species will also use nest boxes if they are available. Across most of their range, Great Crested Flycatchers often incorporate shed snake skins into their nests. Naturalists have long proposed that this was a mechanism to deter predators. A study in Florida found that flying squirrels were less likely to enter boxes with snake skins, and that small mammal predation was lower on eggs in artificial nests under similar circumstances. Great Crested Flycatchers also regularly include strips of plastic in their nests, so it’s also possible that they’re simply attracted to long, flat, translucent objects. 

Snakeskins or not, nests contain 4-8 eggs typically laid by the end of May. These are incubated for two weeks, and the chicks fledge two weeks later. They are tended by their parents for another three weeks, by which point it is almost time for migration. Great Crested Flycatchers are one of the first nesting species to leave in the fall and are hard to find after the end of August. Most spend the winter in Mexico and Central America, but they are also regular in southern Florida at this time. 

Population trends for this species are mixed. Overall, they appear stable across the Northeast, but there are some areas with recent slight declines. In contrast there’s a tendency for increases in the southern United States. A similar pattern (declines in the north and increasing or stable populations in the south) is seen in several other species of aerial insectivores. The causes of differences are uncertain but include geographic variation in threats such as insect declines and climate change.