Monday, April 12, 2010

Tracking the Impressive Migration of Ruddy Turnstones

Using geolocators, Australian scientists have tracked the complete migration cycle of Ruddy Turnstones, one of my favorite shorebird species. The birds in question spend their winters in southeast Australia and breed in the Aleutian Islands.
"We have been amazed at the feats of Bar-tailed Godwit tracked by satellite from Australia and New Zealand to their breeding grounds in the high Arctic and back", said Dr Clive Minton from the Australasian Wader Studies Group. "Unfortunately the size of the satellite transmitters, and the batteries required to power them, precluded their use on smaller shorebirds like Ruddy Turnstone".

The researchers therefore decided to use new 1 gram light-sensor geolocators - supplied by British Antarctic Survey in Cambridge, England - and fitted them to eight Ruddy Turnstone spending their non-breeding season in south-east Australia in April 2009. Four geolocators were eventually retrieved from birds between 20 October 2009 and 8 January 2010.

"All four birds flew 7,600 km non-stop to Taiwan in just over six days, with three apparently travelling together", said Dr Clive Minton. They then flew on to northern Siberia, following separate paths and stopping over at different sites. "By early August, two had moved to Korea and south-eastern Siberia, respectively, but another bird returned to Australia via the Central Pacific!"

The Pacific bird spent 26 July -15 October on the Aleutian Islands before flying 6,200 km across the Pacific in four days to Kiribati, and then it made another four-day, 5,000-km flight to eastern Australia. "Five days later it was back in south-east Australia having completed a 27,000-km round trip", added Ken Gosbell - Chairman of the Australasian Wader Studies Group.
The turnstones were estimated to fly at about 50-55 km per hour (or about 30-35 mph). During their southbound flights, they averaged about 65 km per hour (or 40 mph), which suggests they may have had a tailwind at times. Because the pilot project was so successful, the research team is tagging an additional 60 turnstones with geolocators and extend the project to 30 Greater Sand Plovers and 4 Sharp-tailed Sandpipers. Shorebird migrations have long been known to be among the most impressive performed by any bird species. Thanks to contemporary technology we are getting a better picture of just how impressive shorebird flights can be!