Hummingbirds are captivating creatures that bring vibrancy to New York’s warmer months. These tiny birds, primarily the Ruby-throated Hummingbird, are known for their rapid wingbeats and hovering flight. As summer transitions to fall, many New Yorkers observe a decrease in hummingbird activity, prompting curiosity about their seasonal disappearance. This annual departure is a migratory journey, driven by environmental cues and requiring extensive preparation.
Typical Departure Schedule
Hummingbirds begin their southward migration from New York in late summer, with activity decreasing through early fall. While timing varies year by year, many start their journey in August and September. Peak numbers of Ruby-throated Hummingbirds are observed in early September in New York as they prepare for migration.
Adult males are the first to depart, by the end of August. Females and younger birds, hatched during the breeding season, follow later. By October, the vast majority of hummingbirds have left New York for their wintering grounds in Central America and Mexico. Some individuals may linger into late October, considered stragglers.
Environmental Triggers for Migration
Hummingbird migration is primarily initiated by environmental cues, not simply by cold weather or an immediate lack of food. A significant trigger is decreasing day length, also known as photoperiod. As days grow shorter in late summer and early fall, these changes signal to the hummingbirds that it is time to begin their journey south.
While not the primary trigger, dropping temperatures and diminishing food sources also play a role in reinforcing the migratory instinct. As autumn advances, nectar-producing flowers become less abundant, and insect populations decrease. These environmental signals work in concert to prompt the birds to undertake their long-distance migration to warmer climates with more reliable food supplies.
Pre-Migration Preparations
Before embarking on their migratory journey, hummingbirds undergo significant physiological and behavioral changes. They enter a period of intense feeding, known as hyperphagia, consuming large quantities of nectar and small insects. This increased caloric intake allows them to rapidly build fat reserves, which serve as their primary fuel source for the long flight.
Hummingbirds can gain 25-40% of their body weight, with some even doubling it, before migration. This fat is stored efficiently in various parts of their body, including around organs and along their flanks. Stored fat provides more than twice the energy per gram compared to carbohydrates or protein and also produces water, which helps prevent dehydration during sustained flight. This preparation is important, as some Ruby-throated Hummingbirds undertake non-stop flights of up to 500 miles across the Gulf of Mexico, a journey that can take 18-22 hours.