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Dutch researchers trace migrating gruttos via satellite
Heidenskip adds fame to Frisian village
Tags: Excerpts from the Windmill
GRONINGEN - One of the fifteen godwitses (called grutto in Dutch), that have been equipped with an electronic device, set off on a recent Saturday for Senegal in West Africa, where the bird arrived on the following Tuesday morning. The grutto, nicknamed Heidenskip, appears to have flown from Friesland via Spain and over the Sahara in one stretch. Heidenskip covered the distance of over four thousand kilometers in merely two days of nonstop flying.
Research leader Prof. Theunis Piersma of the University of Groningen calls the Heidenskip’s average speed of nearly eighty kilometres per hour an impressive performance. If the tailwind is subtracted, the bird would still reach a speed of nearly fifty kilometres per hour, calculated the researcher.
This past May in Friesland, Piersma’s research group equipped fifteen black-tailed godwits with transmitters. They want to use the transmitter project to find out exactly how the birds migrate between their winter and summer grounds. The information will help the researchers discover exactly where these birds may need protection. The godwit survey is being conducted with the help of tiny transmitters that are placed into the abdominal cavity of the birds. The research team is updated on the location of the birds at predetermined times via Argos satellites.
Grutto Heidenskip was named after the Frisian village where she was caught on her nest in early May. After the transmitter was inserted into her abdominal cavity, she just continued to brood. Despite the farmer carefully mowing around the nest, she lost her clutch a few days later. After this loss, Heidenskip spent a month building up her energy. During that time she roved around the area near her nest. Then on a Saturday, the bird was last signaled in the Workumerwaard in the south-western part of Friesland. The next transmission positioned her a day later as flying over the Straits of Gibraltar. On the Monday, she was ‘seen’ by the satellite on a beach just to the south of the Mauritanian capital of Nouakchott. The Tuesday morning transmission reading located Heidenskip over the Senegal river, in the border area between Mauritania and Senegal.
In addition to Heidenskip, the godwit Warkum was also ‘spotted’ on the Monday over the Western Sahara. The transmittals placed the gruttos Bakhuzen, Himmelum and Skuzum somewhere in southern Spain, while Starum was flying over Madrid. According to Piersma, at least four of the six godwits lost their clutches of eggs. Gruttoes who manage to raise their chicks require a bit more time to put on weight for the flight south. This transmitted information has made the research team even more aware that godwits reside in the Netherlands only a very short period of time to breed, before quickly returning “home” to Africa. Piersma is cautiously concluding from his transmitter information that the most important bottleneck in these birds’ lives is the time they are spending in the meadows of the Netherlands. The intensive Dutch agricultural methods do not allow enough godwit chicks to reach adulthood and thereby hindering the survival of the species, observes Piersma.
The grutto Heidenskip was outfitted with her transmitter by university researcher Ysbrand Galama who hails from the village It Heidenskip. He was helped by Mauritanian biology student Hacen ould Mohammed el Hacen. Piersma finds it a wonderful coincidence that of the fifteen godwits fitted with a transmitter, Heidenskip is the first to reach West Africa. The bird is really living up to her name, comments Piersma, referring to the 380 It Heidenskip residents who are famous for their relatively high number of sporting heroes, including ditch vaulting (fierljeppen), pole climbing and tug-of-war competitions. To top it off, Heidenskip flew to Hacen’s homeland, Mauritania, where is most likely was from.
The bird transmitter project is one jointly conducted by the University of Groningen, the Alaska Science Center of the US Geological Survey, ecological research bureau Altenburg & Wymenga and the Nederland-Gruttoland coalition. The project is supported financially by the Science Department of the Ministry of Agriculture, Nature and Food Quality and the Province of Friesland. The birds may be followed on the Internet at: www.vogelbescherming.nl/grutto