These tiny birds will lower their body temperature by almost 50 degrees and slow their metabolism in torpor. By fluffing their contour feathers (piloerection), the hummingbirds trap warm air and reduce the number of calories they need to survive the cold.ĭuring cold nights, hummingbirds may enter a sleep-like state called torpor to conserve energy. Hummingbirds do not have down feathers to help insulate them from the cold. As a bonus, metabolizing fat releases twice as much water as carbohydrates or protein, preventing dehydration. There is twice as much energy available to migrating hummingbirds in fat than carbohydrates (nectar) or protein (insects). The protein from the insects will build muscle, while the insects’ fat becomes stored energy for the hummingbirds’ migration. The menu includes nectar needed to fuel the feeding frenzy and nutrient-rich insects to “bulk up” for migration.
In the weeks before migration begins, hummingbirds go on a feeding frenzy called hyperphagia. By early August, male hummingbirds begin migrating south, weeks ahead of the females and hatch-year birds. The male will repeat his performance for the next female to enter his territory. All parenting becomes the responsibility of the female.
If it works, they will mate, and the female will leave to start her brood. When a female enters the territory, he will perform an aerobatic pendulum display flight to impress her. By November, successful migrants are in the tropics, spending their days visiting flowers, eating small insects, and beginning their winter molt.Ī male ruby-throated hummingbird aggressively defends his territory from other male hummers. The trip to the wintering grounds begins in earnest in August and continues through October. The remainder of the summer, hummingbirds build a fat reserve that will fuel their fall migration. Young hummingbirds fledge in July, and a second brood is typical. Courtship, mating, and nest building take place in May.įemales incubate and feed hatchlings through June. The spring migration progresses slowly in March and April as hummingbirds follow the blooming of flowers northward. By the end of February, a migratory restlessness called “ Zugunruhe” sets in.
In January through February, they feed on flower nectar and insects while completing their winter molt. Ruby-throated hummingbirds spend the winter in the tropical warmth of the gulf coast, Florida, Mexico, and Central America. Gulf Coast, Florida, Mexico, and Central America
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