A Blue-gray Gnatcatcher tends its nest in Arkansas. Both sexes cooperate in building the neat, open nest, which takes up to two weeks to build. The nest is 2–3-inch wide and is held together and attached to a branch with spider webbing and decorated with lichen. Because it is supported from below, this kind of nest is referred to as a statant cup. The nest’s high walls are built in flexible layers. The main structural layer is built of fibrous materials like plant stems, bark strips, and grasses, all held together by spiderweb or caterpillar silk. Inner layers become progressively finer, and the roughly 1.5-inch-wide cup is lined with plant down, paper, cocoons, hair, or feathers. The outside is covered with webbing or silk decorated with bits of lichen or bark flakes.
Bird parents have many responsibilities. Aside from sitting on their eggs or feeding the chicks, they must also keep their young safe from predators and parasitism. In the case of the Blue-gray Gnatcatcher, pairs spend nearly two weeks constructing their nest and then covering it in lichens, only to completely dismantle and reassemble it elsewhere if a threat to the young appears. Gnatcatcher parents may relocate their nest up to seven times in one breeding season!
This video accompanies Chapter 11, Breeding Biology of Birds, Handbook of Bird Biology, 3rd Edition from the Cornell Lab of Ornithology and Wiley Publishing.
Recorded by Timothy Barksdale, Macaulay Library