Nancy L. Newfield has been watching hummingbirds at her Louisiana home and lots of other places since 1975. Nancy lost her amateur status years ago, and now writes and lectures on hummers. She is co-author of Hummingbird Gardens, reviewed elsewhere on this site. Nancy is also a licensed hummingbird bander and a recognized authority on hummingbird distribution, behavior, and taxonomy.
The Long GoodbyeSeptember is a bittersweet month for many hummingbirders, numbers of individuals at feeders is at a peak. Gardens resemble avian war zones. Chitters and twitters fill the air. What could be more fun!
Yet all too soon, the birds will be on their way south, going to tropical climes where the food supply is everlasting. The signal to migrate is inborn, regulated by changes in hormonal levels, which are caused by changes in the length of daylight hours, which in turn cause increased appetite - a simplified version of a complex biochemical reaction.
Yet, some hummers are exempt from migration. The Anna's Hummingbird of the Pacific Coast and southern Arizona is not bound by the seasonal urgency that affects most of its North American kin. Neither is the Costa's Hummingbird of southern California and Arizona nor the sedentary subspecies of the Allen's Hummingbird that stays year 'round on the Channel Islands and the Palos Verdes Peninsula of southern California.
These birds have somehow evolved along with their special flowers. They have no need to desert their natal regions in search of a more favorable climate. The climate is favorable for them to reside in the same general area year round. Native flora nurtured by winter rains provide a bountiful nectar supply that supports a nesting season that is out of sync with traditional northeastern concepts. In these places, there is no goodbye.
But, hordes of Ruby-throats, Black-chins, Rufous, Broad-tails and others are indeed moving south. Actually, for Ruby-throats, at least, some males depart as early as early July. The first migrating male Rufous reach southern Arizona from their Pacific Northwestern home range by early July as well. Members of the migratory race of the Allen's will have crossed the border even before then.
In the Rocky Mountains, nearly all hummers will have departed by Labor Day. The same holds true for the northernmost reaches of the Ruby-throat's breeding range. But for most of the eastern U.S., the pace of migration quickens by September. Liberation from parental chores enables males to move out while females are still incubating the progeny of their brief union. Females for their part must wait until young are independent, but they, too, move on as the days begin to shorten. The youngsters, still mastering flight skills and food finding, tarry a bit longer. Yet, their inate signal creates an almost palpable urgency. They must leave and they must put on fat to fuel the rigorous journey.
The time span during which the southward migration takes place is prolonged for a good reason. That way, no natural disaster, even one as widespread as a hurricane, can affect the entire population. Only a small portion of the migrating birds is in one place at one time.
Ruby-throats would seem to be most vulnerable for they are the only species that must cross the broad expanse of the Gulf of Mexico. Other species follow an overland route that is nonetheless hazardous. Though wildflower bloom may be at a peak, it can be extremely variable according to the amount of rainfall that has watered these arid regions in the previous weeks. Even in a wet year, there is never enough nectar for all. Inevitably, some individuals fail to find sufficient food and others become exhausted. These birds can fall prey to any number of predators that await.
Considering the rigors of the journey, it seems a wonder that any hummers survive to return in the spring. Yet, amazingly, sufficient numbers beat the odds. So, for most hummingbirders, the time has come to say "'Goodbye," though perhaps "¡Adios, hasta luego!" is more appropriate and more satisfying.
Copyright © 1996
Nancy L. Newfield