Birds of Brooklyn: Tree Swallow
The fall migration of the tree swallow is one of the most spectacular birding events in the NYC area. As they pass through, the birds cover the outer beaches of Brooklyn, Queens, and both Nassau and Suffolk Counties, where flocks of 10,000 or more birds are not unusual. Smaller flocks fly over BBG and Prospect Park, especially over the lake.
The tree swallow is a small bird with an iridescent blue back and a white belly. It eats insects primarily but will also take some berries; along the coast, it will eat bayberries (sometimes called myrtle berries). Tree swallows usually arrive in our area during the early part of April. They immediately set up housekeeping in cavities in trees, or more often these days, man-made bird boxes.
Tree swallows start their nest with a few layers of grass and then finish it off with a layer of feathers, usually white ones. By the middle of May, a pair will usually have five pure white eggs, which the female incubates for about two weeks. When the babies hatch, they are fed by both parents for almost three weeks, until they fledge. Getting the young tree swallows out of the nest can sometimes be a hard job. The parents will fly by the nesting cavity waving juicy insects in their beaks to encourage the nestlings to pursue them. As they mature, the young tree swallows spend time in flying practice and on learning to capture food and care for themselves.
More: Read about another phenomenal fall migration in Birds of Brooklyn: Yellow-Rumped Warbler
By September, the adults and youngsters are ready to migrate south, where food can be found during the winter months. When the winds of fall start to push into our area from the Northwest, they carry all the adults and juveniles who have bred here and north of us toward the coastline, creating a fabulous display of migrating birds. You might see a river of birds along our coastline in late September or October.