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 ostralegu s). In experiment 1, pairs incubating a clutch were disturbed on their feed ing territory on the mudflat. Disturbance significantly reduced the proport ion 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 oystercatche r pairs with chicks were disturbed by two observers at different distances from the edge of the salt marsh where the chicks resided. Total food collec ted was independent of disturbance, but a smaller proportion of the food co llected was allocated to the chicks with increasing disturbance level. Both experiments demonstrate that human disturbance of foraging in breeding oys tercatchers reduced the amount of parental care, and thus presumably reprod uctive success. (C) 2001 Elsevier Science Ltd. All rights reserved.