Student - 28 februari 2015

Hunting down the right codes

Who? Hendriekus Algra, MSc Forest and Nature Conservation
What? Four months of fieldwork
Where? The southwest of Spain

The Dutch black-tailed godwit, Limosa limosa or ‘Skries’ in Frisian, lays speckled eggs in Dutch meadows every spring and speeds off to Africa at the end of the summer, flying at ninety kilometres an hour. That’s how the story went, but now we have discovered that five per cent of the blacktailed godwits born in the Netherlands spend a large part of the winter in the southwest of Spain and some never even venture to make the crossing.

Professor Theunis Piersma of the University of Groningen, a familiar name because he received the Spinoza Prize last year for his research on migratory birds, asked me to find and study this population. In order to identify the birds at a distance, I had to get up early. This was because the University of Groningen uses a colour-ring code spread over both legs. To read the code, you need to see both legs at the same time, but black-tailed godwits like to stand on one leg. This meant I had to be at my post by sunrise, because that’s when they stretch their legs. As they search for breakfast, they scratch about in ever deeper water, making the codes illegible. The bright sun at that time of day doesn’t make the decoding any easier either. I got another chance at sunset, because that’s when they repeat this ritual. The daylight hours I spent looking for active groups, out and about because they’d been startled by birds of prey or fancied a midday snack.

Sometimes I enjoyed a short Spanish siesta, as did the black-tailed godwits. Every day I drove a rented Nissan Juke from Seville over increasingly decrepit roads to the natural salt marshes, recently harvested rice fields or the fish farms where the black-tailed godwits forage. One wet day, I got stuck in the thick river clay of the Guadalquivir; evidently the Juke was no 4x4! I spent two hours in the mud, scooping away with an asbestos board until I was rescued by two kind-hearted Spaniards. Together, we managed to get the car out but I couldn’t take any more measurements that day. My reception by my Spanish colleagues was heart-warming to say the least, but I advise everyone to learn the language. Especially in a country where English is still in its infancy!


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