Jan B. Hulscher and Bruno J. Ens
William J. Sutherland and Bruno J. Ens
Ventral hammering oystercatchers tend to specialise upon attacking either the right or left valve of mussels. Both in the field and in captivity they initially select medium sized mussels. Selection against small mussels can be understood from the low profitability of small mussels, but large mussels are very profitable. The hammering oystercatchers select thin shelled mussels even though capable of opening ones with thicker shells. Once the preferred prey are depleted, they take thicker and larger mussels. Indirect evidence suggests that within a size class the profitability of thick-shelled mussels is lower. Stabbing birds open larger and thicker mussels than do hammering birds. When feeding on boiled mussels size taken is larger than when feeding on live mussels.
An Illustrated Behavioural Ecology
Jan van de Kam, Bruno Ens, Theunis Piersma and Leo Zwarts
The core of the book is based on studies of shorebirds and other waterbirds (such as ducks, geese and gulls) that migrate along the East Atlantic Flyway. The emphasis is on those using the Dutch, German and Danish Wadden Sea; examples from the rest of the world are also included.
The authors are experts in the fields of bird migration, shorebird behaviour and intertidal ecology, and have contributed much to our current understanding of these subjects. The 300 magnificent portraits of waterbirds in action were taken by Jan van de Kam, one of The Netherlands' foremost wildlife photographers.