Hummingbirds, despite their small stature, undertake remarkable migrations across vast distances each year. These tiny birds, some weighing less than a penny, embark on journeys spanning hundreds or even thousands of miles. Their annual movement is a natural phenomenon that highlights the incredible endurance and navigational abilities inherent in these feathered travelers.
Typical Fall Migration Timelines
Hummingbirds generally begin their fall migration southward from August through October. Ruby-throated hummingbirds, common in eastern North America, often peak in early September, though some start in late August. They gather in areas like Florida, Louisiana, and the South Texas coast during September and October, preparing for the final leg of their journey, which can include a significant flight over the Gulf of Mexico.
Migration timing varies by species and location. Rufous hummingbirds in western North America may begin their southward movement as early as July, traveling down the Rocky Mountains. Northern hummingbirds typically depart earlier than those in southern areas. Adult males often initiate migration, followed by adult females, and then juveniles, a staggered departure that may help reduce competition for dwindling resources.
Environmental Triggers for Departure
The primary cues for fall migration are a combination of environmental factors. Decreasing daylight hours, known as photoperiod, play a significant role as a biological trigger, initiating hormonal changes within the birds. This internal signal prompts them to prepare for the long flight ahead, regardless of immediate weather conditions.
Cooler temperatures also contribute to the migratory urge, signaling the approach of less hospitable conditions. A diminishing supply of natural food sources, such as nectar from flowering plants and insects, serves as another environmental cue. These combined signals, rather than a single factor, prompt hummingbirds to embark on their journey south. Human-provided feeders do not prevent migration, as departure is driven by these innate biological and environmental triggers.
Pre-Migration Preparations
Before migration, hummingbirds undergo significant physiological and behavioral changes. This preparatory phase involves a dramatic increase in food consumption, scientifically termed hyperphagia. During this time, they spend more time than usual feeding on nectar and consuming insects to build up their energy reserves.
A rapid accumulation of fat reserves is a key part of this preparation. Hummingbirds can gain substantial weight, typically increasing their body mass by 25-40% before migration. For example, a Ruby-throated hummingbird might double its weight from 3 to over 6 grams. This stored fat is an efficient fuel source, providing more than twice the energy of carbohydrates or proteins, and also producing water to prevent dehydration during flight.
Assisting Migrating Hummingbirds
Supporting migrating hummingbirds involves providing reliable resources. Maintaining clean feeders with fresh nectar is one effective way to help these birds refuel. Clean feeders every one to three days, depending on temperature, using a solution of one part refined white sugar to four parts water, and avoiding red dyes which can be harmful.
Planting late-blooming, nectar-rich flowers offers a natural food source for passing hummingbirds. Species like Salvia, Cardinal Flowers, Bee Balm, Mexican bush sage, and Mimbres figwort provide valuable sustenance. Avoid premature removal of feeders to ensure late migrants have access to food. Keep feeders up for at least two weeks after the last hummingbird sighting in your area.