Jul 14 2009
Yellow warblers are in Pennsylvania only 10 weeks and in that time they claim territory, build a nest, lay eggs, incubate, hatch eggs, feed young, guide their young to independence and begin to molt. And now in mid-July they’re leaving for home.
A yellow warbler’s annual time budget is amazing. Six months of the year, from October through March, these tiny yellow birds live in Central and South America, as far north as the Yucatan, as far south as Amazonian Brazil, Bolivia and central Peru. They spend four months of the year migrating – about two months each way – and only about two months on their breeding grounds in North America from Alaska to North Carolina. No wonder their breeding season is frantic!
The females are the ones on a tight schedule. The males arrive at the breeding grounds 10 days ahead of the ladies and spend that time staking out their territories. When the ladies arrive they find a mate within one day of arrival. Imagine choosing that fast!
I think they have no time to be picky. The females do all the early work alone. They build the nest, lay the eggs and do all the incubation. By the time the females have been on their breeding grounds for 24 days they have nestlings begging for food. Both parents feed the babies and in 8-10 more days the young have fledged.
Cowbirds cause delays. If a cowbird lays an egg in a yellow warbler’s nest, the female warbler recognizes the problem and builds a new nest on top of the old one, burying the cowbird egg so that she can start over. Other than that she’s in a rush.
Right now she and her mate are getting the kids ready and packing to leave (figuratively speaking). Yellow warbler fall migration peaks around July 31 at Presque Isle State Park, even earlier at Powdermill.
This is a bird in a hurry to get home.
(photo by Chuck Tague)