Birds that migrate long distances have evolved amazing abilities to undertake incredibly long journeys across oceans and continents. The length of time it takes a bird to cross an ocean depends on many factors, including the specific species of bird, weather conditions, time of year, and geographic variables.
Many species of birds migrate vast distances every year, some crossing entire oceans in their annual travels between breeding and wintering grounds. While smaller birds may migrate relatively shorter distances across land, larger seabirds like albatrosses regularly traverse thousands of miles of open ocean on their migratory routes.
The most incredible avian navigators can fly non-stop for days or even weeks as they cross hostile open ocean waters. Their ability to pinpoint their location and direction using cues like the sun and stars, along with sensing the earth’s magnetic field, allows them to stay on course over huge distances.
In this article, we’ll look at some of the ocean crossing feats of different migratory bird species and the factors that determine how long their oceanic journeys take.
The Amazing Migratory Birds That Cross Oceans
Some examples of birds that undertake extreme long-distance migrations across oceans include:
- Arctic Tern – These birds breed in the Arctic summer and migrate all the way to the Antarctic coasts and islands for the southern summer, crossing vast stretches of the Atlantic and Indian Oceans. Total migration is around 44,000 miles roundtrip.
- Bar-tailed Godwit – Breeds in Alaska and migrates 7,000 miles non-stop to New Zealand, flying across the Pacific Ocean for 6-8 days without stopping.
- Great Circle Route Bar-tailed Godwits – A population migrates from Alaska to the Wadden Sea in Europe, taking advantage of tailwinds by crossing the Atlantic Ocean and Europe in a circular route of about 10,200 miles.
- Sooty Shearwater – Migrates from breeding grounds in New Zealand and southern Chile across the entire Pacific Ocean to forage off the Pacific coast of North America.
- Leach’s Storm Petrel – Breeds on islands in the North Atlantic and migrates across open ocean to winter off southern Africa and South America.
These birds demonstrate the incredible feats of endurance and navigation that ocean crossing birds have evolved to complete their annual migrations across continents.
Variables That Determine Ocean Crossing Times
The most important factors that influence how long it takes a bird to complete a trans-oceanic migration include:
Distance
The further the journey, the longer it will take. Migration routes can be thousands of miles depending on the bird’s breeding and wintering ranges. Bar-tailed godwits fly non-stop for 6-8 days to cross the Pacific from Alaska to New Zealand, covering over 7,000 miles.
Flight Speed
Different species have different flight speeds depending on their size and wing shape. Large seabirds like albatrosses can cruise at 50 mph, while smaller songbirds fly around 20-30 mph during migration. The faster a bird can fly, the less time it takes to cover long distances.
Wind Conditions
Favorable tailwinds can significantly boost a bird’s ground speed, cutting journey time considerably. Some migratory routes take advantage of seasonal wind patterns that minimize flight time across oceans. Headwinds and storms can slow progress.
Stopovers
Some migratory birds break up their journeys with stopovers to rest and feed, while others undertake nonstop trans-oceanic flights. Stopovers add time to overall migration but allow birds to refuel for the next leg of the journey. Bar-tailed godwits fly Alaskan-New Zealand nonstop.
Time of Year
Most migration occurs during spring and fall when conditions are optimal, though some birds migrate huge distances to alternate breeding sites in the southern summer.
Examples of Ocean Crossing Times for Specific Migratory Routes
Here are some examples of estimated migration times for birds crossing major oceans:
| Bird Species | Migratory Route | Distance | Estimated Time |
|---|---|---|---|
| Arctic Tern | Iceland to Antarctica | 15,000 miles | 2 months |
| Bar-tailed Godwit | Alaska to New Zealand | 7,000 miles | 6-8 days nonstop |
| Sooty Shearwater | New Zealand to California | 5,000-6,000 miles | 4-6 weeks |
| Great Circle Route Bar-tailed Godwit | Alaska to Wadden Sea | 10,200 miles | 9 days |
These examples illustrate the variations in journey length and duration for different remarkable migratory birds that complete annual intercontinental migrations across oceans.
Physiological and Behavioral Adaptations For Ocean Crossings
To achieve such phenomenal feats of endurance, ocean crossing birds have evolved many unique adaptations to enable them to fly vast distances over water.
Efficient Flying
Specialized wing shape and flight mechanics allow seabirds to fly efficiently for days on end without tiring. Some even have tube nose structures to easily expel excess salt.
Fat Stores
Before migration, birds accumulate fat stores to fuel their journey. The fat provides enough energy to fly 100+ hours nonstop.
Water Conservation
Unique physiological adaptations like specialized salt glands allow seabirds to drink seawater and conserve water on long ocean crossings.
Navigation Abilities
Ocean birds navigate using the sun, stars, and earth’s magnetic cues. They have spatial maps hardwired into their brains to stay on course.
Rest Strateies
Some birds fly nonstop while others employ strategies like resting on the water or switching between half brains to get brief rest mid-journey.
Together these adaptations make it possible for birds to achieve extraordinary nonstop ocean crossing flights up to 10,000 miles.
Conclusion
The time it takes a migratory bird to complete an ocean crossing depends heavily on the distance travelled, flight speed, wind support, and whether the journey involves nonstop flight or stopovers to rest and feed. While crossing times vary widely based on the route, the fastest ocean crossings take advantage of favorable tailwinds that reduce flight time.
Specialized adaptations enable certain birds like Arctic Terns and Bar-tailed Godwits to fly continuously for days or weeks to complete nonstop transoceanic migrations of 7,000 miles or more. These marathon migrators demonstrate the incredible endurance that birds have evolved to undertake some of the most phenomenal migrations in the animal kingdom.
