Hummingbirds are remarkable little birds that capture the imagination with their diminutive size, iridescent plumage, and remarkable ability to hover in midair as they nectar at flowers. These tiny dynamos beat their wings up to 80 times per second, allowing them to fly forwards, backwards, upside down, and to precisely hold their position while lapping nectar through their long, specially adapted tongues.
Though small, hummingbirds are mighty travelers. Most hummingbirds that breed in the United States and Canada migrate south in the fall to spend the winter in Mexico, Central America, and the Caribbean Islands. The Ruby-throated Hummingbird is the most common species seen in Tennessee, and it makes one of the most incredible migratory journeys in the animal kingdom in relation to its tiny body size.
Where Do Ruby-throated Hummingbirds that Breed in Tennessee Go for the Winter?
Nearly all of the Ruby-throated Hummingbirds that nest in Tennessee migrate across the Gulf of Mexico in the fall to reach their wintering grounds in southern Mexico, Central America, or the Caribbean Islands. Their migration is timed precisely; most leave Tennessee by mid-September.
This feat is made even more impressive when you consider that a Ruby-throated Hummingbird weighs only about 3-4 grams, or about the weight of a penny. For their size, their migration across a 500-600 mile wide Gulf is equivalent to a person swimming across the Atlantic Ocean!
Fall Migration Route
In August and September, Ruby-throats start congregating and feeding extensively in Tennessee, Gulf Coast states, and southern Atlantic coast states to build up fat reserves for their long migration. By mid-September, most Ruby-throated Hummingbirds have left Tennessee and started migrating south.
The southbound migration route takes Tennessee’s Ruby-throats first to the coast of the Gulf of Mexico in Alabama, Mississippi, Louisiana, or Texas. Some migrate across land south through Mexico, but most make the incredible nonstop, 18-24 hour flight across the Gulf of Mexico to Yucatan Peninsula.
From there, they spread out over their Mexican and Central American wintering grounds, with most wintering in southern Mexico and Guatemala. A smaller number continue to Panama and Costa Rica.
Wintering Areas
During the winter months of December to March, Tennessee’s Ruby-throated Hummingbirds are residing in tropical broadleaf forests, Citrus orchard groves, and gardens from southern Mexico to Panama. The three most common wintering countries are:
- Southern Mexico
- Guatemala
- Costa Rica
In winter, Ruby-throated Hummingbirds aggressively defend small territories with plentiful flowers and insect food. The availability of food strongly limits their population size in winter, with each bird needing a territory with adequate food.
What is the Ruby-throated Hummingbird’s Spring Migration Route and Timing?
Starting in February, Ruby-throated Hummingbirds begin migrating north through Mexico and along the Gulf Coast to return to their breeding grounds across eastern North America. Most wintering in Mexico start arriving back in Tennessee by mid-April. Here is a summary of their spring migration timing and route:
Early Spring Migration
- February to March – The first Ruby-throats start leaving Mexico, Guatemala and northern Central America and migrate north through Mexico.
- Late March – Earliest returnees start arriving along Gulf Coast of Louisiana, Mississippi, Alabama and Florida.
Mid Spring Migration
- April – Large numbers move north through the Gulf States and up Atlantic Coast.
- Mid April – Ruby-throats start arriving back in Tennessee.
Late Spring Migration
- Late April to early May – Peak spring migration across the Southeast U.S.
- May – Final birds arrive in northern breeding areas in the U.S. and Canada.
In early spring, the returning birds are focused on reaching their breeding grounds as early as possible and claiming the best nesting territories. The males arrive first, followed by the females about a week or two later.
What Triggers Hummingbird Migration and How do They Navigate?
What cues tell the hummingbirds when it’s time to migrate? And how do these tiny birds find their way on migrations of hundreds or thousands of miles?
Migration Triggers
Research shows that a combination of factors trigger hummingbird migration in spring and fall:
- Seasonal daylight changes – Increasing day length in spring and decreasing day length in fall triggers hormones that stimulate migratory restlessness and urge to move north or south.
- Availability of flowers and food – Lack of flowers and food spurs southward migration in fall. Abundance of flowers helps stimulate northward migration in spring.
- Weather patterns – Southward movement in fall is often correlated with the passage of cold fronts that bring north winds. Northbound migration in spring is often timed with warm southern winds.
Navigation
Hummingbirds appear to use several types of navigational cues to find their way on migration:
- Sun compass – Ability to orient direction based on the position of the sun.
- Stars – Migrating hummingbirds use stars for orientation on clear nights.
- Visual landmarks – Recognize and follow geographic landmarks like coastlines, mountains, rivers, etc.
- Magnetic fields – Some evidence migrating hummingbirds may sense the Earth’s magnetic field for direction.
Remarkably, some experienced adult hummingbirds seem able to navigate back to the exact location of their previous year’s breeding or wintering grounds, suggesting they have excellent spatial memories to guide them over long distances.
What are the Dangers Hummingbirds Face During Migration?
Hummingbirds undergo grueling journeys each fall and spring. Their small size makes them vulnerable, and many perils await them along the way:
- Food shortages – Lack of nectar or insect food can lead to starvation.
- Exhaustion and starvation – On long overwater crosses or when facing headwinds, they can become exhausted and depleted of energy, forcing them down into the sea.
- Weather – Storms, high winds, rain/cold temperatures can take a heavy toll.
- Predators – Birds of prey attempt to snatch them in midair.
- Building collisions – Windows, towers, and other structures claim many during migration.
Research estimates roughly 50% of hummingbirds die in their first year. Much of this high mortality occurs during migration when young birds are undertaking the journey for the first time.
How You Can Help Hummingbirds Migrating Through Your Area
Here are some tips to help support migrating hummingbirds on their incredible journeys:
Fall Migration
- Keep feeders up and freshly stocked through September as they build energy reserves for migration.
- Plant native nectar flowers that bloom late summer through fall.
- Supply water for drinking and bathing.
- Let flowering weeds like Spanish Needles grow for food.
- Reduce use of pesticides which kill insect food.
Spring Migration
- Put up feeders and stock nectar in early April for returning birds.
- Ensure abundant native nectar plants are available.
- Provide water.
- Keep cats indoors – a big danger for migrating birds.
With a little planning, you can make your yard an essential migratory stopover and fueling station for hummingbirds heading to or from their breeding and wintering grounds.
Key Statistics on Ruby-throated Hummingbird Migration
Here are some key facts and statistics that summarize the migration of Ruby-throated Hummingbirds that nest in Tennessee:
| Fall Migration | |
| Timing | Most leave Tennessee by mid-September |
| Route | Southeast to the Gulf Coast, then most fly across the Gulf of Mexico to Mexico/Central America |
| Distance | 4,000 – 5,000 miles round trip for birds wintering in Costa Rica or Panama |
| Winter Range | Mexico, Guatemala, Costa Rica, Panama |
| Spring Migration | |
| Timing | Most arrive back in Tennessee in mid April |
| Route | North through Mexico and Gulf Coast states |
| Early Arrivals | Males arrive in Tennessee about 1-2 weeks before females |
Fascinating Facts About Ruby-throated Hummingbird Migration
- Their migration is timed with bloom of flowers all along their migration route to ensure enough food.
- Some fly low over Gulf of Mexico near oil rigs to rest and feed during overwater crossing.
- Young hatchlings migrating in the fall make the round trip journey solo without parental guidance.
- Birdsbanded in east Tennessee have been recovered inBelize, Honduras,and Panama in winter.
- Tennessee’s population swells in fall when birdsalso migrating through from farther north stop in the state.
- Females start migration first in fall, followed shortly after by males and young hatclings.
Conclusion
The migration of the Ruby-throated Hummingbird is an amazing odyssey for a bird that weighs only as much as a penny. Their long journey is driven by instincts honed over thousands of years and made possible by incredible navigational abilities and stamina. With urban sprawl and habitat loss threatening many migratory bird species, understanding hummingbird migration helps us appreciate the challenges they face while highlighting important ways we can support these tiny travelers on their extraordinary biannual voyages across North America.
