Effects of recreational disturbance on the foraging behaviour of waders on a rocky beach

Abstract

Oystercatcher Haematopus ostralegus, Curlew Numenius arquata and Redshank Tringa totanus reacted in a variety of ways to human disturbance. They delayed arrival and departed earlier when disturbed. Vigilance (scan rates) increased with the vigour of human activity and the birds were more vigilant in the higher shore zones, but there was no corresponding decrease in food searching (peck rates). Prey capture rates of Oystercatcher and Curlew apparently increased with moderately close human disturbance. Undisturbed birds may not have been foraging at maximum rates and rested periodically during the low tide period. Characteristic avoidance behaviour elicited by disturbance differed between the species; Curlew and Redshank typically stopped feeding and, if they left, flew away, whereas Oystercatcher walked away. This difference may be related to plumage crypsis. Flight distances of all species were very low. Habituation may be an important response to regular but benign disturbance, reducing the disturbance-induced decrease in feeding time to a level which may be compensated for, at least in summer, within the normal low-tide foraging period.