Migrations are the seasonal movements of animals between their summer breeding grounds and their winter habitats. Other than leaves turning to gold, red and orange, I can think of nothing in nature that signals the change of seasons more clearly or remarkably.
As recently as last week, I was speaking with birders in both Franklin and Clinton counties who still have hummingbirds visiting their feeders. Both were inquiring as to whether their feeders should be left up. The thinking is that all hummingbirds should be southbound by now, and that removing the feeders will encourage stragglers to get a move on.
Worldwide, there are more than 300 species of hummingbirds, all in the western hemisphere. The ruby throated hummingbird (Archilochus colubris) is the only species found in eastern North America. They are solitary creatures, neither living nor migrating in flocks.
And, since it’s believed that all hummingbird migration is prompted by decreasing daylight and not by changes in temperature or food availability, removing feeders will not encourage them to leave. Because they need to fatten up if they are going to survive the journey south, there is no reason not to go on feeding them. In fact, several sources recommend leaving feeders up until two weeks after the last hummingbird is seen feeding.
In order to sustain enough energy to support their elevated metabolisms, hummingbirds must consume nectar, either from suitable flowers or from sugar-water solutions in feeders. Like all living creatures, they also need protein. While they do receive some from pollen that gets stuck to their tongues and bills, in order to get the amount necessary to remain healthy, an adult hummingbird must eat several dozen insects daily.
They are adept at snatching insects out of the air or from spider webs, off of leaves and flowers, and out of holes left in trees by sapsuckers. Before heading south, hummingbirds will often gorge themselves on insects to put on the layer of fat needed to nourish them through the journey.
There is little available research about hummingbird migration, and for good reason. To study migration, you need to band large numbers of birds, but hummingbirds are nearly impossible to catch. For starters, they’re able to fly at speeds up to 60 miles an hour. They can rotate their wings in a complete circle, so they’re able to fly in any direction — up, down, sideways, backwards — and to change direction instantly or maintain a stationary position in mid-air. They can fly upside-down and perform rollover maneuvers if attacked by another bird.
Even if you were able to band a large group of hummingbirds, what do you think the odds are of locating and recapturing those birds once they’re thousands of miles away? To the best of my knowledge, a ruby throated hummingbird has never been banded at a summer nesting site and recaptured in its overwintering grounds, or vice-versa. In fact, as far as I can tell, of the ruby throated hummingbirds that have been captured and banded, only a few have ever been recaptured. And most of those were recaptured within 10 miles of the original banding site.
The second option for studying migration involves attaching transmitters to birds. A transmitter small enough to attach to a bird weighing 3.5 grams or less does not exist.
Males typically start their migration before females, and late departures are not uncommon among immature birds. Often, due to illness or injury, a bird will be unable to leave on schedule. A recovering hummingbird preparing for a 2,000-mile journey will appreciate any source of nectar it can find, especially as flowers become scarce. It’s also likely a hummingbird at your feeder now is a bird that has arrived from Canada and is just passing through.
Bird migrations are often spread out over prolonged periods so hurricanes or other catastrophic weather events or natural disasters will not annihilate the entire species. Whatever the reason, you can be sure that a hummingbird coming to your feeder late in the season will appreciate the nourishment.
One last thought, as much as I get a kick out of the idea that hummingbirds will hitch a ride on the backs of other, larger migrating birds like geese, there’s not a shred of evidence to support this quirky, albeit imaginative and eccentric, notion.
Richard L. Gast, Extension program educator II, Horticulture, Natural Resources, Energy; agriculture programs assistant, Cornell Cooperative Extension of Franklin County, 355 West Main St., Suite 150, Malone, 12953. Call 483-7403, fax 483-6214 or email email@example.com.