Variation in the feeding success of sperm whales: Temporal scale, spatial scale and relationship to migrations

1. Variability in a measure of the feeding success of sperm whales, defecation rate, was calculated over temporal scales ranging from 5 h to 4 years, and spatial scales ranging from 100 to 5000 km. 2. Sperm whale feeding success was not obviously linked to any sub-annual environmental cycles, with the possible exception of time of day. 3. Variability in feeding success over temporal scales of 1-64 days, and spatial scales of 100 km, was about 60% of the long-term mean, but reached 130% of the long-term mean over time intervals of 2-4 years and distance intervals greater than 500 km. 4. During periods of days characterized by low feeding success groups of sperm whales moved greater distances. 5. Migration over ranges of about 300 1000 km allows sperm whales to maintain high biomass and low reproductive rates in an environment which, at any location, contains long, unpredictable periods of food shortage.