Knots receive eminent visitor

University of Groningen Professor of Animal Ecology Theunis Piersma and his colleagues from the Royal Netherlands Institute for Sea Research (NIOZ) received an eminent visitor during their fieldwork on the knot, a wading bird, on Banc d’Arguin in Mauretania. None other than Christine Lagarde, Managing Director of the International Monetary Fund, dropped by.

Lagarde did not just watch, she released a knot equipped with a radio transmitter onto the sands. This bird is part of a special experiment on the Banc d’Arguin to prove that diet preference is the cause of physical differences between birds of the same species. The results of the study were published on 16 June in the Journal of Animal Ecology , and the IMF boss made a cameo appearance in a photo that accompanied the article.

‘We were just preparing to release the birds when we saw a great cloud of sand billowing in the distance’, says NIOZ researcher Thomas Oudman, the first author of the article. ‘It turned out to be a huge convoy of Land Rovers. In the middle Land Rover was Christine Lagarde, who was visiting the field station in the Parc National du Banc d’Arguin, where we have been researching birds from the Wadden Sea for years.’

Appetite for travel

At that point, Oudman and his colleagues had just caught almost 50 knots on the Mauritanian tidal flats, the winter residence of many knots that breed in the Arctic Circle and refuel in our Wadden Sea during the journey. ‘It has recently become possible to track the behaviour of knots in the wild by affixing a radio transmitter to their backs’, explains Oudman. Although knots may look very similar, research has shown that they differ in dietary preference and appetite for travel.

These differences relate to the size of their gizzards. In some birds this is very muscular because they eat very hard shells, which they swallow in one gulp and crack in their stomach. Oudman: ‘Knots that move a lot have a small stomach, and we now know why. We have been able to show that rather than adapt their behaviour to their stomachs, their dietary preference itself is the cause of differences between them.’ Just like in humans. ‘We find it completely normal that human behaviour differs and that this has an effect on all sorts of physical features. Why should it be any different in animals?’

Banc d’Arguin

Like the Dutch Wadden Sea, the Banc d’Arguin is an intertidal zone. This unspoiled area spans more than half of the Mauretanian coast and is a UNESCO World Heritage Centre, but despite this it is under threat. Ecologists from the University of Groningen like Theunis Piersma and his colleagues from the NIOZ have been researching this relatively unspoiled ecosystem, one of the most important overwintering areas for migratory birds in the world, since the 1980s.