Ardea Official journal of the Netherlands Ornithologists' Union |
Leopold M.F., van Elk J.F. & van Heezik Y.M. (1996) Central place foraging in Oystercatchers Haematopus ostralegus: can parents that transport Mussels Mytilus edulis to their young profit from size selection? ARDEA 84 (A): 311-325 |
Central place foraging (CPF) was studied in eleven pairs of Oystercatchers Haematopus ostralegus, that transported Mussels Mytilus edulis to their young in nesting territories located at varying distances from the shore. None of these pairs showed a strong selection for large Mussels. The strategy of sharing the available food optimally between parents and young is described in a mathematical model. This model predicts size selection in any likely situation and is thus rejected. Instead, the parents appeared to bring food to their young only after having satisfied their own hunger. A second model describing this strategy, predicts that selection for more profitable Mussels has the effect of keeping the parents away from the young for too long in most situations, and hence increases the risk of predation. Only birds transporting prey over large distances were found to select slightly for size where they had a wide range of sizes of prey to choose from. |