Ruby-throated hummingbirds are the only hummingbird species that breed east of the Mississippi River. They spend the summer across much of the eastern United States and Canada, with the core breeding range centered around the Great Lakes. When autumn arrives, ruby-throats embark on a strenuous migration south to their wintering grounds in Central America and Mexico.
Fall Migration Overview
Ruby-throated hummingbirds begin migrating south in August or September. The precise timing depends on a number of factors, including food availability, weather conditions, and their internal clocks. The southward migration occurs over a period of 6-8 weeks. Most ruby-throats leave the northern parts of their breeding range by early October. The birds continue moving south throughout the autumn months, with the last stragglers departing the southernmost states by November.
Ruby-throats migrate alone, not in flocks. They fly during the day, stopping each night to rest and refuel. Their small size makes them vulnerable to bad weather, so they carefully watch weather patterns and will delay migration if winds are unfavorable. If weather permits, ruby-throats may fly 20+ hours nonstop over open water, pausing just briefly to feed at flowers along the way. It’s an arduous trip that requires immense energy reserves.
Wintering Range in Mexico and Central America
The majority of ruby-throated hummingbirds that breed in eastern North America spend the winter in southern Mexico and Central America. A few key details about their wintering grounds:
- Southern Mexico is a major wintering area, especially along the Pacific and Gulf Coasts.
- Belize, Guatemala, Honduras, Nicaragua, Costa Rica, and Panama also host huge numbers of wintering ruby-throats.
- Preferred habitat is open areas with plenty of flowering plants and small trees where they can perch.
- Many winter in lower mountain valleys between 1,000-4,000 feet in elevation.
- A small number may overwinter as far south as western Panama.
Ruby-throats are widespread throughout these tropical wintering regions, inhabiting fields, residential areas, parks, and forest edges that provide adequate nectar supplies. Flowers like Salvia, Heliconia, and various fruit trees flourish in the subtropical climate and sustain the wintering hummingbirds.
Populations on the Gulf Coast and in Florida
A portion of the ruby-throated hummingbird population winters along the U.S. Gulf Coast, particularly in Florida and coastal Texas. These areas host resident populations of ruby-throats year-round instead of having them migrate south into Mexico or Central America. However, the Gulf Coast population appears to be distinct from the interior eastern North American breeding population. Banding studies show little crossover between the groups. The interior population migrates across the Gulf of Mexico while the coastal group stays put along the shoreline.
Spring Migration Back North
Ruby-throats begin moving north again in February and March. Their spring migration mirrors the southbound route in reverse. The earliest arrivals reach the U.S. Gulf Coast states in February. By mid-March, they are returning to their breeding areas across the Southeast and Mid-Atlantic regions. The northernmost breeding grounds are reoccupied in May as the birds continue moving north through April and early May.
As with the fall migration, weather conditions influence the timing and pace of the spring return. Ruby-throats cannot make much headway during periods of cold temperatures, rain, or strong headwinds. Ideally, they migrate on warm days with winds blowing from the south. The journey north covers the same immense distances as the autumn trip, requiring the tiny birds to fly up to 500 miles nonstop across the Gulf of Mexico. It’s an incredible feat of endurance.
Differences Between Fall and Spring Migrations
While the overall migration routes are the same in spring and fall, there are some key differences between the seasonal journeys:
- The fall migration is more prolonged, lasting 6-8 weeks compared to 4-6 weeks in spring.
- More Ruby-throats migrate close along the Atlantic coast in fall but cross the Gulf of Mexico in spring.
- The pace quickens in spring so they can reach the breeding grounds and establish territories.
- Most older adult males migrate first in spring, followed by adult females and young birds.
- Young birds migrating for the first time often get delayed by bad weather.
Tracking Ruby-throat Migration
Ornithologists have been banding Ruby-throated Hummingbirds for decades to track migration patterns. More recently, tiny geolocator tags have allowed very precise monitoring of individual hummingbirds throughout the annual cycle. This technology is revealing new details about timing, routes, stopover sites, and variability among birds. Banding and tagging programs continue to expand our knowledge about the migratory cycle of Ruby-throated Hummingbirds.
Incredible Migrators
Weighing just 3-4 grams, ruby-throated hummingbirds are the smallest migratory bird in North America. Their 5,000 mile annual round-trip journey is an incredible feat of endurance for such tiny athletes. Their persistence allows us to enjoy ruby-throats through the summer, then welcome them back home each spring after their extraordinary migration.
