Experimental evidence for effects of human disturbance on foraging and parental care in oystercatchers

We carried out two experiments to quantify effects of human disturbance on foraging and parental care in European oystercatchers (Haematopus ostralegus). In experiment 1, pairs incubating a clutch were disturbed on their feeding territory on the mudflat. Disturbance significantly reduced the proportion of time that the clutch was incubated, but also the proportion of time that the pair spent on the mud flat. In experiment 2, foraging oystercatcher pairs with chicks were disturbed by two observers at different distances from the edge of the salt marsh where the chicks resided. Total food collected was independent of disturbance, but a smaller proportion of the food collected was allocated to the chicks with increasing disturbance level. Both experiments demonstrate that human disturbance of foraging in breeding oystercatchers reduced the amount of parental care, and thus presumably reproductive success. (C) 2001 Elsevier Science Ltd. All rights reserved.