Initial results from light level geolocator trials on Ruddy Turnstone Arenaria interpres reveal unexpected migration route

With the development of archival light level geolocators weighing only 1 g, their deployment on medium size waders is now possible. Trials showed that attachment via leg flag rather than backpack harness was preferable because of the large weight gains of Ruddy Turnstone during preparation for migration. Geolocators attached to leg flags were fitted to six Ruddy Turnstones at Flinders, Victoria, SE Australia, and four were retrieved the following season. All four birds had made an initial non-stop 7,600 km flight, in six days, to Taiwan, with three probably travelling in the same flock. Individuals then followed separate paths through E Asia before locations became indiscernible in early June in E Siberia as birds encountered continuous daylight. Brief data were recorded for two birds at the beginning of southward migration through E Siberia in early August before the damaged light sensor stalk on the geolocator failed, as another had also done on the breeding grounds. The fourth bird, without a stalked light sensor in its geolocator, was in the Aleutian Islands, SW Alaska, when locations again became discernible on 26 July. It remained there until 15 October and then made a 6,200 km non-stop flight to the Gilbert Islands, western central Pacific in four days. After another prolonged stopover it departed on 29 November reaching E Australia in four days (5,000 km) and arrived back at Flinders on 8 December. This bird had made a round trip migration of around 27,000 km. Between 26 June and 14 July, when it was in the Arctic, the light data record of this bird suggested that it had been incubating. A further 60 geolocators will be deployed on Ruddy Turnstones in SE Australia in March/April 2010.