Foraging Behavior and the Effect of Human Disturbance on the Piping Plover (Charadrius melodus)

Abstract

Foraging behavior of Piping Plover (Charadrius melodus) was studied using a focal animal approach from 1985-1986. Time devoted to foraging decreased as vigilance (time devoted to being alert) increased. Variations in vigilance were explained by beach, reproductive stage, brood size, time of day, and number of people nearby. Overall, Piping Plovers foraged from 46-79 sec., were alert for 14-57 sec., and displayed or ran from people for 1-8 sec. in the 2 min. samples. Plovers at sites less disturbed by people (Little Beach, Holgate) generally devoted more time to foraging and less time to vigilance than birds at the other sites. Time devoted to foraging was generally higher in May, lower in June, and increased again in July. Plovers that were incubating or caring for chicks spent less time foraging than those that had lost their chicks. Chicks spent less time foraging and more time being alert, running, and crouching than did their parents foraging during the same time periods. With increasing brood size, chicks spent less time foraging and more time running or crouching although the number of people nearby did not vary. Behavior was correlated within members of a pair: birds spent less time foraging as their mates increased time devoted to alertness, being off the nest, or displaying. When brooding birds increased alert time, their mates increased their alertness and displaying, and decreased foraging time. As the number of people near foraging plovers increased, time devoted to running and crouching increased and time devoted to feeding decreased. It appears that the presence of people is stressful for breeding adults and chicks, forcing them to spend significantly less time foraging, perhaps accounting for decreased overall reproductive success.