Cape Town - Tipping the scales at less than 100g, it weighs one third less than your Blackberry phone.
Yet the Ruddy Turnstone can fly as much as 27 000km a year, and more than half a million kilometres during its lifetime.
An astonishing piece of research tracking some of its global movements was recently announced in Australia, and publicised locally through the website of UCT’s Animal Demography Unit (ADU).
Ruddy Turnstones are among birds known as Palearctic migrants that move annually between their breeding grounds deep in the Arctic circle during the northern (boreal) summer, and their southern hemisphere summer (austral) feeding grounds in South Africa and Australia – and then back again.
This is an annual journey that can reach 27 000km. And because this species is known to live for at least 20 years, this means some will fly well over 500 000km in their lifetimes.
Ornithologists know this from bird ringing, but a relatively new device is providing even more exciting data. The sensor data logger, or geolocator, weighs just one gram and is attached to a bird’s leg.
The geolocator records the time of sunrise and sunset each day in relation to GMT, and the length of the days and nights reveal how far north or south the bird is – its latitude – while the times of sunrise and sunset reveal how far east or west it is – the longitude.
The big problem for ornithologists is that they have to catch the individual bird again each year to retrieve the geolocator and download the information, the ADU explains on its website.
Last year, for the first time, researchers from the Victorian Wader Study Group in Australia captured a Ruddy Turnstone in successive years, 2009 and 2010, after it had completed its annual 27 000km round-trip migration – and the results were astonishing.
The tiny geolocators had been attached to birds in mid-April on a beach at Flinders, Victoria, in south-east Australia.
The retrieved data showed that the turnstones generally started their northward migration with an initial non-stop flight of around 7 600km in six days to Taiwan or adjacent regions.
“There they refuel on the tidal flats before moving north to the Yellow Sea and northern China. They then make a flight of over 5 000km to the breeding grounds in northern Siberia, arriving in the first week of June,” explains Dr Clive Minton of the study group.
Of particular interest to the researchers was the variation in the return flight, with no two birds following the same route.
Minton and his colleagues say they are concerned about the ability of turnstones and similar migrant waders to cope with massive habitat changes occurring as a result of large land reclamation and urban development projects.
Professor Les Underhill, head of the ADU at UCT, agrees.
Locally about 100 or so are recorded every summer on Robben Island, with the largest numbers – 2 000-plus – found at Langebaan Lagoon.
“We’ve never had a ring recovery from South Africa on to the breeding grounds – only along the migration routes,” Underhill says.
“So we are really quite envious of the Australian study, and the only barrier to us getting the same information is a substantial block of funding for these amazing new devices.”
Each geolocator costs about R1 200.
l For details of the Australian research, see http://internal.adu.org.za/upload/uploads/ruddy_hell_ruddy_turnstone_flies_27000_km.pdf and also http://adu.org.za.
john.yeld@ inl.co.za - Cape Argus