Vogels leren beter hoe muiltjes te eten

Along the Wadden Sea coast of Texel, herring gulls and carrion crows have added slipper limpets (Crepidula fornicata) to their diet. They bring the animals to the dike to eat them and leave the shells on the bicycle-road along the dike. Slipper limpets live in chains. Up to 2009, the birds usually consumed only the lowest slipper limpet from such a chain, leaving the rest intact on the road. Now, 20 January 2010, I found for the first time five empty slippers within a radius of a few decimeters on the road, and all freshly consumed. They had been part of one chain, as I could nicely fit the shells in their original chain. Unfortunately, I have not seen the bird at work. However, this indicates that the carrion crow (or herring gull) had learned not to stop eating after the lowest slipper limpet, but to continue with the rest.