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.