PREDATOR-PREY RELATIONSHIP BETWEEN WILSON-PLOVERS AND FIDDLER-CRABS IN NORTHEASTERN VENEZUELA

In coastal lagoons of northeastern Venezuela, resident Wilson's Plover s (Charadrius wilsonia cinnamominus) forage almost entirely on fiddler crabs (Uca cumulanta). During the non-breeding season, particularly f rom November to January, plovers are seldom on foraging sites during d aylight but forage more during nighttime. Objectives of this study wer e to document the availability of Uca cumulanta and to determine if ni ght foraging by Wilson's Plovers in tropical areas is tied to abundanc e or activity of fiddler crabs. We used a time-lapse video camera to m onitor the number of crabs outside burrows, both during nighttime and daytime. Results show that crab activity was almost exclusively diurna l. Although some crabs were active after sunset, particularly from May to August, diurnal activity of crabs was always 3-10X higher than noc turnal activity. Therefore, Wilson's Plovers feeding patterns are not exclusively a function of the period when their main prey is most acti ve or abundant. Results best support our previous interpretation that nocturnal foraging in Wilson's Plover is a strategy for avoiding diurn al predators.