Scientists have discovered that several species of western hummingbirds, some from as far away as Alaska, are coming through the East in fast-growing numbers every autumn, sometimes months after ruby-throated hummingbirds that nest here have flown south – often not appearing until the snowflakes have started to fly.
What's more, researchers who are studying these rugged travelers say you can help by keeping your hummingbird feeders filled through at least Thanksgiving, and contacting them if you attract a hummingbird.
We're seeing the development of a new migration route and wintering area for these birds right before our eyes, but we need the public's help to better understand what's happening, said Scott Weidensaul of Schuylkill County, one of six federally licensed hummingbird banders in Pennsylvania, all of whom are collaborating to learn more about these far-traveling migrants.
Hummingbirds that appear here in autumn are usually a species known as the rufous hummingbirds, which nests in the Pacific Northwest and Alaska, and which normally migrates to Mexico for the winter, Weidensaul said.
In recent years, he said, increasing numbers of rufous hummingbirds have been appearing in the East, usually showing up in Pennsylvania in October and November. One has appeared in the Mountain Top area this year.
What usually happens is that after all the ruby-throats are gone, someone notices a single hummer still at the feeder, and they assume it's one that forgot to migrate, according to Bob Mulvihill of Pittsburgh, one of the cooperating ornithologists.
But birds don't ‘forget' to migrate – chances are it's a rufous hummer that's already traveled thousands of miles to get here, and which looks enough like a ruby-throat that correct identification requires that the bird be caught and carefully measured by a licensed bird bander experienced with hummingbirds.
The wayward hummingbirds probably have a genetic mutation affecting their migratory orientation, sending them southeast instead of due south, Mulvihill said – which in these days of milder climates and an abundance of feeders and natural food, works out fine for them.
Last fall, dozens of rufous hummingbirds were sighted at feeders across Pennsylvania – five of them in Northampton County alone, three of which remained throughout the winter.
Leaving up a feeder will not prevent any bird, including hummingbirds, from migrating, Weidensaul said – the migration instinct is just too powerful.
What we're seeing are hummers that use feeders in Pennsylvania as way stations on continent-spanning migrations. They may stay only a day, or they may linger for months, but the vast majority finally leave by late December or early January to spend the rest of the winter much farther south, on the Gulf Coast, he said.
You can help by keeping a hummingbird feeder (filled with a solution of one part plain white sugar and four parts water), until at least Thanksgiving, Pulcinella and his colleagues say.
If you see a hummingbird of any kind at your feeder after Oct. 15, you can contact any of the six banders in the state, one of whom will come to your home, harmlessly trap, band and release the hummer.
It could be that your colorful visitor will help unlock the secrets that these trans-continental travelers carry with them in their tiny, iridescent bodies.
Scott Weidensaul, Schuylkill County: firstname.lastname@example.org
Bob Mulvihill, Allegheny County: email@example.com
Nick Pulcinella, Chester County: firstname.lastname@example.org
Sandy Lockerman, Dauphin County: email@example.com
Wayne Laubscher, Clinton County: firstname.lastname@example.org
Ember Jandebeur, Lackawanna County: email@example.com