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Hummingbird Research
Traditionally, only one species of hummingbird – the ruby-throated – was found East of the Great Plains, departing each September to winter in the tropics. But in recent years, growing numbers of western hummingbirds of almost a dozen species have been appearing in the East and Southeast, usually showing up in autumn and winter. Scott Weidensaul is part of a continental network of dozens of hummingbird banders trying to document and understand this emerging phenomenon.
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Each autumn and early winter, Weidensaul traps and bands vagrant western hummingbirds in the mid-Atlantic region, primarily in eastern Pennsylvania. Most of the western hummers being reported there are rufous hummingbirds (Selasphorus rufus), which breeds from the northern Rockies and Pacific Northwest to southcentral Alaska, and which ordinarily winter in central Mexico. Smaller numbers of the almost identical Allen's hummingbird (S. sasin) of California, as well as calliope, broad-tailed, black-chinned and Anna's hummingbirds, are also reported regularly from the region.
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A female rufous hummingbird, banded in Dauphin County, Pa. in October 2005. Western hummingbirds like this one have become increasingly common in the East every fall and winter. |
One hypothesis is that these hummingbirds suffer, in effect, from bad software; because for most birds migration is a genetically encoded behavior, those born with mutations to those genes may not orient correctly, and may go in directions they aren't supposed to go. This may explain why small numbers of western hummingbirds have always appeared in the East from time to time. Although they are remarkably hardy in cold (even sub-zero) temperatures, most probably never survived the winter, especially in presettlement times.
However, changes in the landscape, and the ever-warmer winters of the past century, may be combining to make the East and especially the Southeast perfectly hospitable to these birds. Those that survive and return to their breeding grounds are, in all likelihood, passing on their once-unfavorable genes to new generations. Banding studies in the East suggest the number of wintering hummingbirds is increasing dramatically, and that we may be seeing the rapid evolution of a new migratory route and wintering area for these birds.
Although most Eastern homeowners take down their hummingbird feeders when the last rubythroats depart in August or September, these western species don't usually appear until much later in the fall – October or November, sometimes as late as December, in the latitude of Pennsylvania. For that reason, it's a good idea to leave at least one feeder up and filled through at least Thanksgiving – and to contact a bander (below) if you have a hummingbird in autumn.
These hummingbirds do not need to be "rescued," as they sometimes are by well-meaning but misguided people who think it is better to keep them in captivity, or ship them south. This is illegal as well as unwise. The hummingbirds are healthy and well-adapted to their new situation; enjoy them, but please don't interfere.
Weidensaul is affiliated with the Hummer/Bird Study Group, based in Alabama, which has been a leader in studying this emerging phenomenon. HBSG banders are active in most states in the East, Midwest and South. If you live in this region and have a hummingbird that you believe is not a rubythroat coming to your flowers or yard, or if you have a hummingbird of any sort after Oct. 15 in Pennsylvania, get in touch with Weidensaul or one of the other HBSG banders listed here.
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They will come to your home, capture and band the hummingbird, and then immediately release it to continue its migration. The information gleaned from such research is vital for understanding how these hummingbird populations are changing.
(Homeowners are often fooled by hummingbird moths, a type of day-flying sphinx moth that looks remarkably like a hummingbird, hovering at flowers to drink. Some species are even rusty orange in color, like a male rufous hummingbird.)
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A hummingbird moth
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