A conservation group has tracked a migration for the ages, in which a male bar-tailed godwit flew from Alaska to New Zealand without taking a single break.
As the Guardian reports, the bar-tailed godwit departed southwestern Alaska on September 16 and arrived 11 days later at a bay near Auckland, New Zealand. The bird, designated 4BBRW (for the blue, blue, red, and white identification rings attached to its legs), was tracked by Global Flyway Network, a conservation group that studies long-distance migrating shorebirds.
Bar-tailed godwits (Limosa lapponica) are exceptional birds, featuring some mind-bogglingly long migratory routes. The wading birds spend their summers in the arctic regions of the Northern Hemisphere (where they breed) and then fly south for the winter, in some cases as far as Australia and New Zealand. Bar-tailed godwits are fast and lightweight, with wingspans around 70 to 80 cm long.
Bar-tailed godwits looking to relocate from Alaska to New Zealand must make an epic flight over the Pacific Ocean. For 4BBRW, this resulted in a record-breaking nonstop flight, in which the bird flew 12,854 km, reports the Guardian. The bird was equipped with a 5gm satellite tag, which allowed for GPS tracking. The scientists said the total length of the journey is probably closer to 12,200 km after accounting for rounding errors.
The previous nonstop flight record belongs to a female bar-tailed godwit, who flew 7,257 miles (11,680 km) during a similar journey in 2007. Arctic terns (Sterna paradisaea) travel more than 50,000 miles (80,000 km) each year, so they deserve mention as having the longest migratory routes of any bird (or any animal for that matter), though they make lots of stops along the way.
4BBRW departed Alaska following a two-month stint in which it feasted on clams and worms, the Guardian reports. This bird would’ve reached New Zealand sooner save for strong winds that pushed him toward Australia. The bird, who attained a maximum speed of around 89 km per hour, probably didn’t sleep during its 11-day journey, as Jesse Conklin, a researcher with the Global Flyway Network, told The Guardian.
Scientists aren’t entirely sure how these birds are capable of making their journeys without eating or sleeping, but they’ve got some ideas, as a 2011 Lund University press release described:
One explanation is that they consume unusually little energy compared with other species of bird. Anders Hedenström [an ecologist at Lund University] has calculated that the bar-tailed godwit consumes 0.41 per cent of its body weight each hour during its long flight.
“This figure is extremely low compared with other migratory birds,” he says.
However, other factors also play a role. It is important to have the right ratio of body weight to size to be able to carry sufficient energy for the entire flight. The energy mainly comprises body fat, and to some extent also protein. It is also important to have an aerodynamic body shape so that air resistance is minimised. A further success factor is flight speed. The bar-tailed godwit is a quick flyer, which means that it can cover long distances in a reasonable time.
In terms of navigation, Conklin told the Guardian that bar-tailed godwits might be using landmarks in the form of islands to guide them to their destinations. The birds may also have internal compasses that sense Earth’s magnetic field.
Sadly, bar-tailed godwits are listed by the IUCN as a Near Threatened species, as their population is on the decline. The birds face no shortage of threats, from residential and commercial development through to aquaculture, oil and gas drilling, and pollution.