Effects on five species of shorebirds of experimental closure of a beach in New Jersey: implications for severe storms and sea-level rise.

For management, it is important to understand the factors that affect foraging efficiency of birds during migration, especially in the face of severe storms and sea-level rise. An experiment was conducted whereby a beach used extensively by migrant shorebirds and people was open and experimentally closed to human activity to examine factors affecting feeding when there was no disturbance, with the beach opened or closed to human activity, and following disturbances. When the beach was closed, the factors affecting the percent of shorebirds foraging varied by species, but involved the number of conspecifics or other shorebirds, location along the beach, and number of raptors. Overall, 30% of flocks were disturbed as a function of type of disturbance, location along the beach, and whether the beach was open or closed. These data suggest that individuals, vehicles, and raptors influence the ability of shorebirds to forage undisturbed, indicating the importance of having some sections of important stopover beaches where shorebirds can feed and roost undisturbed by human activity. A corollary is that other parts of the beach can be freely used by people; environmental health can encompass both protected areas for shorebirds and open areas for fishing and recreation. Severe storms and sea-level rise will limit beach space for both human and avian activities, and understanding mitigation for both is essential to wise adaptive management.