Hummingbirds are amazing little birds that capture our imagination. Their ability to hover mid-air and dart between flowers is mesmerizing. But one of the most incredible things about hummingbirds is their migratory journey each year between their summer breeding grounds in North America and their winter homes in Mexico and Central America.
When do hummingbirds migrate?
Hummingbirds start their southern migration in late summer or early fall, anywhere from July through early October depending on the species and local conditions. This coincides with the end of the breeding season when food sources become more scarce further north. They follow routes known as flyways over mountains, coastal areas, and across the Gulf of Mexico. The journey south can take several weeks with many stopovers to rest and refuel along the way.
How far do they travel?
The distance a hummingbird travels between its breeding and wintering grounds can be astonishing. For example, the tiny Rufous Hummingbird nests in Alaska and northern Canada during the summer. By early fall, these hummingbirds begin a 3,000 to 4,000 mile journey south to Mexico for the winter. The Ruby-throated Hummingbird may log between 1,500 to 2,500 miles moving between the eastern United States and Central America.
How do they navigate such long distances?
Hummingbirds are able to make these epic journeys due to some remarkable abilities:
- Keen eyesight – They can see landmarks, mountains, coastlines, and other features to orient themselves.
- Internal compass – They have a magnetic compass sense that helps keep them on course even when landmarks are not visible.
- Ability to compensate for wind drift – They can detect side winds and adjust their course to stay on track.
- Use of the sun’s position – On sunny days they orient themselves based on the location of the sun.
- Memory and recognition – Adults likely remember landmarks and locations from previous migratory trips.
What routes do they take?
There are four main flyways hummingbirds use to migrate south:
- Western: Follows the Rocky Mountains and Sierra Madre Occidental range through the western United States into Mexico
- Central: Traces the Great Plains through Texas into Mexico
- Mississippi: Follows the Mississippi River and Gulf Coast through the southern U.S.
- Atlantic: Traces the U.S. Atlantic coast into Florida across the Caribbean and to Central America
Some hummingbirds also make daring non-stop flights of 500 miles or more across the Gulf of Mexico rather than take a longer land route around it.
What dangers do they face?
Making an extremely long migratory journey over unfamiliar terrain is not without risks. Hummingbirds face many threats along the way:
- Exhaustion and starvation – Finding enough food requires visiting hundreds or thousands of flowers daily. Fat reserves allow only a day or two without food.
- Predators – Birds of prey can ambush them at stopovers. Bullfrogs, lizards, and insects prey on young hummingbirds.
- Severe weather – Storms or high winds can blow them dangerously off course.
- Collisions – Windows, buildings, vehicles, communication towers, and other structures pose collision risks.
Research estimates between 20-50% of juveniles, and around 30% of adults perish during migration from such hazards. However, the resilience of survivors ensures continuation of the species.
How do they know when to migrate?
What cues tell hummingbirds it’s time to start migrating? Key factors include:
- Food availability – As flowers go dormant and food becomes scarce in late summer, migration instincts kick in.
- Day length – The shortening days of late summer trigger hormonal changes for migration.
- Weather – Arrival of fall-like weather helps spur the migration season.
- Weight gain – Ideal migration weight triggers an impulse to depart.
- Persistent restlessness – An increasing urge to move on and seasonal wanderlust builds up.
These influences all act together to help hummingbirds sense when the timing is right to begin migrating south.
How do they prepare for the journey?
Hummingbirds go through some remarkable physiological changes to ready themselves for migration:
- Hyperphagia – They eat constantly in late summer to store fat needed for the long trip.
- Weight gain – Some may double their weight by adding several grams of fat.
- Larger flight muscles – The pectoral muscles that power flight can increase by over 25% in size.
- Sharpened digestive system – The digestive system becomes more efficient at getting energy from food.
These changes allow hummingbirds to take on the extreme demands of migration.
What is their migration flight strategy?
Hummingbirds use some remarkable flight strategies while migrating:
- Flying relatively low to the ground to watch for food sources and landmarks
- Flapping wings up to 70 times per second for maneuverability
- Gliding and coasting for short periods to rest their wings
- Taking advantage of tailwinds when possible
- Rotating primary flight feathers one at a time to avoid molting all at once
By alternating flapping, gliding, and coasting, they can travel hundreds of miles a day while conserving precious energy.
Where do they stop over?
Hummingbirds break their migration into multiple short flights or “hops” stopping to rest and feed. Favored stopover spots provide:
- Plentiful nectar sources like flowers, shrubs, and feeders
- Protected shelter such as trees, shrubs, or thickets
- Streams, lakes, or fountains as a water source
Migrating hummingbirds are often found stopping in gardens, parks, backyards, orchards, fields, woodlands and other locations that offer food, water and cover.
How long do they stay at stopovers?
Length of time at a stopover depends on factors like:
- The amount of fat reserves remaining
- Weather conditions
- Habitat quality
- Time of year
Shorter stops early in migration may only be 1-3 days. As fat stores dwindle later in migration, stops increase to 5 days or longer to rest and feed extensively.
What do they eat along the way?
While migrating, hummingbirds get energy from:
- Nectar – from flowers and feeders offers quick carbohydrates.
- Sugar water – an emergency backup when flowers are scarce.
- Insects – provides essential protein and fat.
- Sap – from wells drilled in trees by woodpeckers or sapsuckers.
Replenishing fat reserves is critical at each stop. Hummingbirds can consume up to half their body weight in nectar daily while migrating.
What happens when they reach their winter home?
Once they reach their destination in Mexico or Central America, hummingbirds enjoy the mild climate while defending winter territories. Key activities include:
- Feeding on flowers, nectar feeders, and insects
- Courting mates or cementing pair bonds
- Possible nominal breeding and raising of a few young
- Roosting – entering a nightly hibernation-like torpor to conserve energy
They remain in their warm winter habitats until increasing daylight and food supplies further north stir their migration instincts once again in early spring.
Do they migrate north alone?
In spring, hummingbirds make the return trip north individually. Some patterns include:
- Males tend to depart a few weeks ahead of females
- Adults precede juveniles (who then rely on instinct over experience)
- Shorter weekend sprints due to more abundant food along the way
As soon as they arrive back on their breeding grounds, they begin the courtship rituals that will continue the nectar-fueled cycle of hummingbird life.
Incredible migrators
The diminutive hummingbird is one of nature’s great marvels. That a creature weighing mere grams can travel thousands of miles, navigating over mountains, deserts, and oceans is astonishing. Their annual odyssey is fueled by incredible tenacity and a driving imperative to survive.
