Every year, hummingbirds make an incredible migration covering thousands of miles from their breeding grounds in the United States and Canada to their winter homes in Mexico and Central America. This fall migration is driven by the need to find food and survive the cold winter months in the north. Understanding the fall migration patterns of hummingbirds provides fascinating insight into the biology and behavior of these small but mighty birds.
When does hummingbird migration start?
Hummingbirds begin their fall migration at different times depending on the species and local conditions, but early August through late September is the key period. The ruby-throated hummingbird is one of the first to migrate, starting in July and August. Rufous hummingbirds migrate in August and early September. Allen’s and Anna’s hummingbirds are some of the last to migrate, leaving their breeding grounds as late as October.
The timing of migration depends on a number of factors. As days get shorter and temperatures drop in late summer, flower availability declines, signaling to hummingbirds that it’s time to move on. Cold snaps and a lack of food may prompt earlier migration. Individual hummingbirds also play a role, with older males tending to migrate before females and young birds.
Where do the hummingbirds migrate from and to?
The majority of hummingbirds that breed in the United States and Canada migrate south to Mexico and Central America for the winter. Here are the main migration routes and wintering sites for common hummingbird species:
- Ruby-throated hummingbirds breed across eastern North America and migrate to southern Mexico, Central America, and Florida.
- Rufous hummingbirds breed in northwestern North America and migrate through western states like Idaho and Nevada to winter along the Pacific coast of Mexico.
- Allen’s and Anna’s hummingbirds nest in California and the Pacific Northwest then migrate south to Mexico’s Baja California peninsula and southern California and Arizona in the U.S.
- Costa’s hummingbirds breed in the southwestern deserts and winter in Mexico’s Baja California.
- Black-chinned hummingbirds nest throughout the western United States and migrate to Mexico for winter.
A few hummingbird species, like the buff-bellied hummingbird and calliope hummingbird, migrate all the way from the United States and Canada to Panama and Costa Rica for the winter.
How do hummingbirds know when to migrate?
Hummingbirds migrate in response to changes in daylight, temperature, and food availability rather than relying on a set internal clock. As days shorten in late summer, flowering plants begin to wane, signaling to hummingbirds that it’s time to move south where nectar-producing flowers are still abundant.
In addition to external cues, hummingbirds appear to use magnetic fields to help guide their migration. Scientists have discovered deposits of magnetic material called magnetite in the head and neck of hummingbirds. They believe hummingbirds may use an internal compass based on the Earth’s magnetic field to help orient themselves during migration.
What is the migratory route for hummingbirds?
Hummingbirds follow established migratory routes or flyways on their northbound and southbound journeys. These routes are shaped by geographical features like mountains and coastlines. Here are some of the main hummingbird migration flyways in North America:
- Atlantic flyway – Along the Atlantic coast for species like ruby-throated hummingbirds migrating between eastern Canada/U.S. and Central America/Mexico.
- Mississippi flyway – Follows the Mississippi River corridor for Anna’s and rufous hummingbirds.
- Central flyway – Through the Central Plains for calliope hummingbirds and others migrating north and south through the central U.S.
- Pacific flyway – Along the Pacific coast for Allen’s, rufous, and other western hummingbirds migrating to wintering grounds in Mexico.
Narrow corridors like mountain passes and isthmuses are also important migration routes, especially in Mexico and Central America. For example, some ruby-throated hummingbirds funnel through the 12-mile wide Talamanca Mountains in Costa Rica.
How many miles do hummingbirds migrate?
The total migratory journey varies by species, but most hummingbirds travel hundreds to thousands of miles between their breeding and wintering grounds. Some of the most extreme hummingbird migrations include:
- Ruby-throated hummingbirds may log over 2,000 miles traveling between Canada and Central America.
- Rufous hummingbirds fly up to 3,900 miles one-way between Alaska and Mexico.
- Tiny calliope hummingbirds fly approximately 2,600 miles each fall and spring between the northwestern U.S. and Mexico.
- Costa’s hummingbirds migrate over 1,500 miles between the southwestern U.S. and northwest Mexico.
The smallest hummingbirds really do make some of the most incredible and lengthy migrations in the bird world relative to their tiny size.
How fast and high do hummingbirds migrate?
During migration, hummingbirds fly during the day when conditions are optimal and rest at night. They can cover an astonishing 20-40 miles per hour and fly at altitudes generally ranging from a few hundred feet up to 12,000 feet.
However, weather radar data suggest hummingbirds may fly considerably higher during migration. One study detected probable hummingbird movements at heights up to 21,000 feet in the skies over the Gulf of Mexico!
Faster wind speeds at higher altitudes may allow hummingbirds to conserve energy during long ocean crossings. Altitudes from 5,000 to 10,000 feet probably balance the physiological demands of high-elevation flight against favorable winds for small birds.
How do hummingbirds physically prepare for migration?
Hummingbirds undergo several changes to prepare for the physical demands of migration:
- Fueling up – In the weeks before migrating, hummingbirds feed intensively and store additional fat reserves to provide energy for the journey.
- Weight gain – Some hummingbirds may nearly double their weight before migrating by building up fat stores.
- Feather maintenance – Molting and replacement of worn feathers occurs in late summer to improve flight performance.
- Organ changes – Some organs like the heart, liver, and flight muscles temporarily enlarge to accommodate higher metabolic demands.
With their lightweight bodies and supercharged metabolism, hummingbirds are uniquely adapted for the sustained vigorous exercise of long-distance migration.
What are the hazards faced by migrating hummingbirds?
Hummingbirds face many challenges and threats during migration, including:
- Lack of food sources – Finding adequate nectar to fuel migration can be difficult, especially during ocean crossings.
- Inclement weather – Storms, high winds, and precipitation can force hummingbirds down and possibly lead to exhaustion or death.
- Predators – Peregrine falcons, shrikes, and other birds prey on hummingbirds during migration.
- Artificial lighting – Light pollution may disorient hummingbirds and draw them off course at night.
- Habitat loss – Development has disrupted some traditional migration stopover sites.
Research using tiny tracking devices attached to migrating hummingbirds will provide more insight into the threats they face during migration.
Do hummingbirds migrate alone or in flocks?
Hummingbirds are solitary migrants for the most part and do not fly in coordinated flocks like many songbirds. However, major geographical barriers like the Gulf of Mexico do lead to concentrations of individual birds along migration corridors at the same time.
At key stopover spots, dozens or even hundreds of hummingbirds from the same species may congregate in a small area to rest and refuel. But they remain on their own schedule, each bird navigating and timing its own migration.
How do hummingbirds cross major barriers like the Gulf of Mexico?
Non-stop water crossings over long distances like the Gulf of Mexico and Caribbean Sea represent major obstacles for migrating hummingbirds. A round trip migrant like the ruby-throated hummingbird may cross the 500-mile wide Gulf up to three separate times every year.
To accomplish this feat, hummingbirds build up substantial fat reserves and make the crossing in a single overnight flight. On windy nights, they likely ascend to higher altitudes where faster winds help propel them across water. Staying over land as much as possible by island hopping also helps reduce open water crossings.
Do all hummingbirds migrate or do some species stay put?
Whether a hummingbird migrates, makes small local movements, or stays resident year-round depends on the species and habitat:
- Long-distance migrants – Most breeding hummingbirds in the U.S. and Canada migrate south, including ruby-throated, rufous, calliope, and others.
- Short-distance migrants – Some species like Anna’s hummingbird may only migrate short distances to warmer winter areas in the same general region.
- Year-round residence – Tropical species like the white-necked jacobin live in suitable habitat and don’t migrate.
In mild coastal areas, Anna’s and Allen’s hummingbirds establishing non-migratory populations farther north than their traditional range. Climate change may drive range shifts and reduce migration distances for some species.
What are the key threats and challenges facing migrating hummingbirds?
Some of the major threats and conservation challenges for migrating hummingbirds include:
- Habitat loss – Development has eliminated many stopover sites hummingbirds rely on during migration.
- Pesticides – Chemicals reduce insect prey and contaminate nectar sources hummingbirds need to fuel migration.
- Climate change – Mismatched timing between migration and flower blooming may make finding food harder.
- Window collisions – Hummingbirds frequently collide with buildings and homes during migration.
- Light pollution – Artificial lights can disorient hummingbird migrants and draw them off course.
Protecting a chain of stopover habitats and maintaining native nectar sources and insect populations are key to successful hummingbird migration across North America.
How does weather and climate impact hummingbird migration?
Weather patterns and climatic conditions have a significant influence on the timing, duration, and path of hummingbird migration each year:
- Warm weather and abundant flowers may delay fall departure and extend breeding seasons.
- Cold snaps and early frosts promote earlier fall migration.
- Strong headwinds may slow migration speed and extend travel time.
- Favorable tailwinds can accelerate migration, especially at higher altitudes.
- Drought may force hummingbirds to move on when flowers dry up faster.
- Heavy rain or storms may ground hummingbirds for longer refueling periods.
Over the long term, climate change also threatens to disrupt the synchrony between timing of hummingbird migration and flower availability along their route, which may severely impact some species.
Conclusion
The fall migration allows hummingbirds to escape declining food in the north and survive cold winters. But it’s also an epic and perilous journey for these tiny birds. Hummingbirds traverse thousands of miles, flying by day and resting by night, as they return to winter homes in Mexico and Central America. Along this arduous trip, they face many threats and challenges in locating enough food and overcoming obstacles like the Gulf of Mexico. This amazing migration undertaken by some of the world’s smallest birds highlights the power and resilience of nature. Understanding and protecting the habitats hummingbirds rely on across North America is crucial to ensure these aerial jewels continue their extraordinary seasonal journeys for generations to come.