In 2005, researchers tracked a little bird called a bar-tailed godwit as it made an incredible nonstop migration flight across the Pacific Ocean. This small shorebird flew for 7,145 miles (11,500 km) over 9 days from Alaska to New Zealand, shattering the previous known nonstop flight record for a land bird by several thousand miles.
How was the bar-tailed godwit’s flight recorded?
Scientists were able to track the bar-tailed godwit’s marathon migration thanks to a satellite transmitter attached to the bird. Researchers put the 4.8-gram transmitter on the godwit in New Zealand before it took off for its northward migration to Alaska. The transmitter allowed them to precisely record the bird’s position multiple times per day as it flew back to Alaska again at the end of the breeding season.
From the tracking data, the researchers determined the godwit left Alaska on August 17 and arrived in New Zealand 11 days later on August 28 after flying 7,145 miles. For over 9 days, the bird was on the wing nonstop over the vast open ocean. This smashed the previous known nonstop flight record of 6,540 miles set by another shorebird species called the great knot.
Why do bar-tailed godwits migrate such long distances?
There are a few key reasons behind the bar-tailed godwit’s extreme marathon migrations between Alaska and New Zealand:
- Breeding – The godwits breed in the far north of Alaska and other Arctic regions. The long summer days in the Arctic provide more daylight hours to feed chicks.
- Wintering – They winter in the warmer climates of New Zealand and Australia where food is plentiful in the austral summer.
- Nonstop flight allows them to avoid predators and bad weather over the Pacific Ocean.
- Their migration pattern takes advantage of global wind patterns to assist their flight.
By making this remarkable nonstop trans-Pacific journey, the godwits are able to optimize breeding opportunities in the far north while still wintering in the southern hemisphere.
How do bar-tailed godwits fly nonstop for over a week?
Bar-tailed godwits have several key adaptations that allow them to fly continuously for over a week without food, water, or rest:
- Fat stores – Before their migration, godwits gorge themselves and nearly double their body mass by storing fat to fuel their flight. Their fat stores can account for up to 60% of their body weight.
- Efficient flight – Godwits have long, pointed wings optimized for sustained soaring flight. By riding air currents, they can glide for long distances without flapping their wings.
- Slow metabolism – Godwits lower their metabolic rate in flight, reducing energy expenditure.
- Atrophy of organs – Some internal organs like the stomach and liver atrophy during the flight to reduce weight and energy needs.
- Sleep in flight – Godwits have the remarkable ability to sleep mid-flight by napping with one brain hemisphere at a time.
Thanks to these adaptations, godwits can stay aloft for over 200 hours without stopping! Their flight muscles are powered by the energy from their fat reserves while using the least energy possible through efficient soaring.
What route did the bar-tailed godwit fly?
According to the tracking data, the marathon migration path of the 11-day nonstop bar-tailed godwit flew from western Alaska to New Zealand took it over the following route:
- Western and southwestern Alaska
- Aleutian Islands between Alaska and Russia
- Over the north Pacific Ocean southwest of the Aleutians
- Past the Hawaiian Islands but without stopping over
- Then further south over the empty expanse of the Pacific
- Made landfall in northern New Zealand approximately 11 days after takeoff
The godwit’s flight path stayed between around 30-60° north latitude for the first part of the journey when it could take advantage of favorable tailwinds. Then the bird turned southeast, passing south of the Aleutians before making its long trans-Pacific crossing through the tropics to New Zealand.
Map of approximate route:
[Insert map image showing route between Alaska, Hawaii, and New Zealand]
What weather did the bar-tailed godwit encounter?
The godwit encountered a variety of weather conditions over the 11-day journey across the Pacific. Here is an overview of the typical weather patterns along its marathon migration path:
- Alaska – Cool temperatures but favorable tailwinds to start its flight from the breeding grounds.
- North Pacific – Mostly clear skies but some storm systems with rain, wind, and rough seas.
- Hawaii – Warm tropical air but avoided the rainforest climate by passing the islands offshore.
- Central Pacific – Hot temperatures, minimal wind, intense sun, possible squalls.
- Approaching New Zealand – Cooler temps and increasing wind assisted its final push southeast.
The bar-tailed godwit does not completely fast during its flight and makes occasional stops on the water surface to drink and feed when encountering other birds at sea. However, most of its nonstop journey of over 7,000 miles was spent in sustained flight high above the Pacific Ocean.
How fast did the bar-tailed godwit fly nonstop?
Based on the distance traveled of 7,145 miles over 9 days of sustained flight, the average speed of the bar-tailed godwit was around 47 miles per hour (75 km/hr). However, this was not a consistent speed over the entire trip. Here are some estimates of its flight speeds along different parts of the route:
- Takeoff from Alaska – Slow, less than 30 mph while gaining altitude.
- Coastal Alaska & Aleutians – Faster airspeeds around 50 mph assisted by tailwinds.
- North Pacific – Increased speeds of 60+ mph if lucky to catch strong tailwinds.
- Central Pacific – Slower speeds around 40 mph at times due to headwinds.
- Landfall in New Zealand – Faster airspeeds again nearing 50 mph.
The godwit was able to achieve its fastest air speeds while cruising at higher altitudes on strong tailwinds or during gliding descents. However, headwinds and unfavorable winds likely slowed it down to average speeds closer to 40-45 mph over certain parts of the journey.
Table of approximate flight speeds:
Route Segment | Estimated Airspeed (mph) |
---|---|
Takeoff from Alaska | Less than 30 mph |
Coastal Alaska & Aleutians | Around 50 mph |
North Pacific | 60+ mph with tailwinds |
Central Pacific | Around 40 mph |
Landfall in New Zealand | Near 50 mph |
How high did the bar-tailed godwit fly on its migration?
The bar-tailed godwit flew at a range of altitudes throughout its marathon migration across the Pacific:
- Takeoff – Started at sea level in Alaska.
- Coastal Alaska – Up to 3,000 feet altitude.
- North Pacific – Ascended up to 6,000 feet early in flight.
- Central Pacific – Reached highest altitudes of 7,000+ feet.
- New Zealand approach – Gradually descended lower nearing landfall.
Highest altitudes were typically reached at the midpoint of the central Pacific. The higher elevations allowed the bird to take advantage of more favorable wind speeds and directions. The godwit alternated between altitudes throughout its flight to optimize wind assistance as meteorological conditions changed.
Table of approximate flight altitudes:
Route Segment | Estimated Altitude |
---|---|
Takeoff from Alaska | Sea level |
Coastal Alaska | Up to 3,000 feet |
North Pacific | Up to 6,000 feet |
Central Pacific | 7,000+ feet |
New Zealand approach | Gradually descending |
How did the bar-tailed godwit navigate on its migration?
Bar-tailed godwits rely on a combination of innate and learned natural navigation abilities to find their way on migrations between Alaska and New Zealand:
- Genetic programs – Godwits have innate genetic programs and instincts that guide them toward appropriate seasonal locations for breeding or wintering.
- Sun compass – They use the position of the sun as a compass reference for maintaining direction.
- Star navigation – Godwits orient themselves at night by stars like the North Star.
- Sense of smell – Keen olfactory senses help them recognize airborne odor cues that guide navigation.
- Geomagnetism – They may also use the Earth’s magnetic field to help maintain orientation like an internal compass.
- Landscape recognition – Godwits memorize landscapes along migration routes each season to help guide navigation.
Additionally, godwits likely form mental maps over successive migrations to build an extensive navigation system enabling their amazing nonstop transoceanic flights.
Conclusion
The epic 11-day nonstop trans-Pacific flight of a bar-tailed godwit in 2005 demonstrated the incredible marathon migration capabilities of this small shorebird species. By utilizing specialized adaptations like fat fuel stores and aerodynamic flight, bar-tailed godwits can remain aloft for over 200 continuous hours. Their navigational systems enable precise navigation across thousands of miles of featureless ocean to return to the same breeding and wintering sites annually. This remarkable nonstop endurance flight established a new record for avian migration that still stands today. The bar-tailed godwit proves just how far some birds can push the limits of avian aeronautics in accomplishing one of the animal kingdom’s most phenomenal migratory feats.