Reproductive success and foraging behavior of the osprey at Seahorse Key, Florida

Abstract

During 1972 there were 15 active osprey [Pandion haliacetus] nests on the 62.5 ha of Seashorse Key, Florida [USA]. The osprey population on this key produced 0.73 young/nesting female which is 0.95-1.30 young/nesting female necessary to maintain a stable population. Adult ospreys were successful in 18.6% of their fishing attempts. The fishing technique of the osprey is at least a partially learned behavior: adults required only 5.4 attempts/catch and 38.3 min/catch, but the young required 12.6 attempts and 77.3 min/catch. Pesticide analyses of 3 osprey eggs indicated low levels of organochlorines and polychlorinated biphenyls. Eggshells (n = 7) were approximately 9% thinner than shells collected prior to 1947.