Hummingbirds are remarkable little birds that capture the imagination of people around the world. Their iridescent plumage shimmers in the sunlight as they dynamically dart from flower to flower, beating their wings up to 80 times per second. Hummingbirds migrate long distances every year, traveling between their breeding grounds in North America and their wintering grounds in Mexico, Central America, and the Caribbean. This round-trip migration can cover thousands of miles for some species. Along their migration route, hummingbirds may encounter severe weather events such as tropical storms and hurricanes. Hurricanes and tropical storms are cyclonic storms that form over tropical or subtropical waters in the Atlantic Ocean, Gulf of Mexico, and eastern Pacific Ocean. So how do these diminutive birds cope when dangerous weather overlaps with their migration schedule?
When do hummingbirds migrate?
Hummingbirds generally migrate in the spring and fall to take advantage of blooming flowers and nesting conditions in different habitats. Here are the typical migration windows for hummingbirds in North America:
- Ruby-throated hummingbird – Spring migration from February to May, fall migration from August to November
- Rufous hummingbird – Spring migration from February to June, fall migration from June to August
- Allen’s hummingbird – Spring migration from March to May, fall migration from July to September
- Calliope hummingbird – Spring migration from April to June, fall migration from June to September
- Broad-tailed hummingbird – Spring migration from April to June, fall migration from July to September
- Black-chinned hummingbird – Spring migration from April to June, fall migration from June to October
As you can see, the peak migration period overlaps significantly with the Atlantic hurricane season, which runs from June 1 to November 30 each year. So how do hummingbirds cope when a hurricane impacts their migratory path?
How do hummingbirds prepare for migration?
Hummingbirds go through several physiological and behavioral changes to prepare for their long migration journeys each season:
- Fat storage – Hummingbirds nearly double their body weight before migration by building up fat reserves. This provides energy for their flights over the Gulf of Mexico and other barriers.
- Flight muscles – The flight muscle mass of Ruby-throated hummingbirds increases by 25-40% prior to migration, allowing them to fly farther and longer.
- Hyperphagia – Hummingbirds enter a phase of hyperphagia or excessive eating before migration, increasing their food intake by up to 100% to store fat.
- Migratory restlessness – As the migration period approaches, hummingbirds become physiologically restless and energetic, exhibiting behaviors like flying in loops and circles.
- Orientation – Hummingbirds use celestial cues from the sun, stars, and magnetic fields to orient themselves for migration.
These adaptations help prepare hummingbirds for the long-distance flights and inclement weather they may encounter during migration.
How do hurricanes impact hummingbird migration?
Hurricanes can influence hummingbird migration in a few key ways:
- Altered timing – Hummingbirds may delay or speed up migration to avoid hurricanes and severe weather. GPS tracking has shown hummingbirds waiting up to 2 weeks longer than normal before crossing the Gulf of Mexico to avoid storms.
- Blown off course – Strong winds and rain from hurricanes can push migrating hummingbirds hundreds of miles off their normal route. Banding stations track many vagrants after big storms.
- Loss of food sources – Hurricanes may damage or destroy nectar sources hummingbirds rely on during migration, forcing them to find alternatives.
- Increased mortality – Exhaustion, starvation, predation and injury may increase during migration through hurricane zones, raising mortality rates.
- More coastal crossings – Hummingbirds may shift migration to cross at narrower points along the Gulf Coast when hurricanes are active offshore.
Researchers are still studying the full impacts, but it appears hurricanes significantly influence migration patterns, timing, and demographics for hummingbirds.
How do hummingbirds survive hurricanes?
Hummingbirds have adaptations and strategies that help them survive hurricanes:
- Fat reserves – Extra fat stores give hummingbirds extra energy to withstand long storms and food shortages.
- Wind resistance – Their small size and low body mass reduce wind resistance and improve stability in high winds.
- Sheltering – Hummingbirds may seek shelter in thick vegetation, tree cavities, buildings, or other structures.
- Energy conservation – They can lower their metabolic rate and enter torpor to conserve energy when food is scarce.
- Feather adaptations – Their small, streamlined feathers are less likely to be damaged by wind and rain.
- Displacement – Allowing themselves to be displaced helps avoid exhaustion from fighting hurricane-force winds.
- stops – Making frequent stops gives hummingbirds places to shelter and refuel after expending energy fighting winds.
Banding and tracking studies show that hummingbirds are surprisingly resilient in surviving even major hurricanes, especially when they have time to build sufficient fat reserves beforehand.
How can humans help hummingbirds through hurricanes?
Here are some ways people can support hummingbirds before, during and after hurricane season:
- Provide supplemental feeding with nectar through late summer and fall.
- Avoid trimming plants and trees used by hummingbirds for shelter.
- Keep feeders up until migration ends; refill when possible after storms.
- Report sightings of vagrant hummingbirds blown off course via citizen science networks.
- Participate in hummingbird banding to help track migration impacts.
- Plant native flowers and trees that hummingbirds rely on along their route.
- Limit use of pesticides that can build up in the food chain.
- Provide shelter such as dense bushes and facilitate stopover habitats.
With some careful planning, we can help these tiny migrators complete their remarkable journeys despite the challenges posed by severe weather events.
Key takeaways on hummingbirds and hurricanes
- Hurricanes disrupt hummingbird migration through altering timing, blowing birds off course, damaging food resources, and increasing mortality.
- Hummingbirds prepare with fat storage, muscle building, hyperphagia, restlessness, and orientation before migration season.
- Survival adaptations like fat reserves, wind resistance, sheltering, energy conservation and displacement keep hummingbirds resilient in storms.
- People can help by providing supplemental feeding, maintaining shelters, tracking vagrants, planting flowers, and facilitating stopovers.
- Understanding the intersection of hummingbird migration and hurricane season is key to supporting resilient hummingbird populations.
Conclusion
Hummingbirds are a fascinating example of the long migrations many birds undertake each year across incredible distances. Their migration timing during the peak Atlantic hurricane season means these tiny aerialists must contend with severe weather events beyond their control. Fortunately, hummingbirds have many adaptations that help them survive hurricanes and tropical storms during their epic journeys. Providing some extra support through conservation efforts, citizen science initiatives, supplemental feeding and facilitating stopovers can go a long way to ensure resilient hummingbird populations in the face of climate change and increasingly severe hurricane seasons. By studying the intersection between hummingbird migration and hurricanes, we can gain crucial insights into how birds cope with extreme weather and a changing climate across an annual transcontinental migration.
