Bird Species Takes “Non-Stop Flight” to a Whole New Level

During their south-bound migration, bar-tailed godwits travel non-stop from their breeding grounds in Alaska to their winter grounds in New Zealand. (Illustration credit: USGS)

During their south-bound migration, bar-tailed godwits travel non-stop from their breeding grounds in Alaska to their winter grounds in New Zealand. (Illustration credit: USGS)

Bar-tailed godwits, a type of shorebird, have knocked the eastern curlew off its pedestal and taken over the title as non-stop migration champions. A team of researchers, led by Robert Gill, Jr., at the USGS Alaska Science Center based in Anchorage recently tracked a group of migrating bar-tailed godwits using satellite technology. A female bird referred to as E7 left the Alaskan breeding grounds and flew nonstop directly to its wintering grounds in New Zealand–a trip of over 11,680 kilometers. The flight took eight days, with no stops for food, water, or rest. E7’s flight is the longest direct flight ever recorded for a bird.

The researchers also tracked the flights of eight other females and two males. Seven of the females flew an average of 10,153 km over a period of (at most) 9.4 days. The two males’ flights were of a slightly shorter length, and took place over a period of (at most) 6.6 days.

The researchers monitored the birds’ flight using satellite transmissions. Female birds were implanted with a tiny satellite tracker. Males, which are smaller in size than females, were banded with lightweight external satellite trackers on their legs. Both males and females were also marked with a numbered leg band so that researchers could easily identify individuals in the field. The scientists followed the birds’ migration path in the air by monitoring the latitude and longitude coordinates the birds passed as they flew across the Pacific Ocean.

The southern migration of the bar-tailed godwit from Alaska to New Zealand is the longest known non-stop migration of any bird. On their north-bound return trip back to Alaska, the birds break their migration into two flights. First, they fly from New Zealand to the Yellow Sea in eastern Asia. After resting there, the birds continue their flight on to Alaska.

This female bar-tailed godwit was implanted with a satellite transmitter and given a leg band marked "E1" so that researchers could track its whereabouts in the air and in the field. (Photo credit: Jan van de Kam, NL/USGS)

This female bar-tailed godwit was implanted with a satellite transmitter and given a leg band marked “E1” so that researchers could track its whereabouts in the air and in the field. (Photo credit: Jan van de Kam, NL/USGS)

In studying the bar-tailed godwits’ southern-bound migration, the scientists also discovered that the birds time their migration with favorable tail winds that aid in their flight south. This discovery indicates the importance of weather patterns to the birds’ annual migration. Scientists worry that global climate change could disrupt this connection significantly.

While this study has answered some of the researchers’ questions about the migration of bar-tailed godwits with regard to distance and amount of time it takes, a number of mysteries remain. For example, the scientists wonder how the birds navigate, how they assess weather conditions, and at what altitude they fly. Further research will be necessary to answer these questions.

The full results of the scientists’ research are reported in the October 21st online edition of the Proceedings of the Royal Society B.

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