Time and Activity Budget of Ospreys Nesting in Northern California

Time and activity budgets provide quantitative descriptions of an animal's behavior, and aid in assessing its modes of reproduction and foraging (Orians 1961, King 1974). Hence, they have been obtained for a diverse array of birds (e.g., Verbeek 1972, Kushlan 1977, Wakeley 1978 and references therein), including several species of raptors (Stendell 1972, Balgooyen 1976, Tarboton 1978, Wakeley 1978; J. R. Koplin and co-workers, unpubl. data). Green (1976) and Stinson (1978) recently studied time and activity budgets of Ospreys (Pandion haliaetus) nesting in Scotland and Virginia, respectively. However, Green measured only certain activities during the breeding season, and Stinson studied Ospreys only after the eggs hatched. My objectives were to compile a detailed time and activity budget of Ospreys nesting in northern California, compare the budgets of Ospreys nesting in various locations, and document and assess the division of labor exhibited between the sexes by nesting Ospreys.