The merits and implications of travel by swimming, flight and running for animals of different sizes

Simple models are presented of the energetics of annual migrationand of central place foraging, taking account of the speed andenergy cost of the journeys. They are applied to insects, fish,birds and mammals of a wide range of sizes, which travel byflapping or soaring flight, by swimming or by running. It isshown that annual migrations of several thousand kilometresare unlikely to be beneficial except for marine mammals andflying birds. Marine mammals and large flying birds are theanimals most likely to be able to benefit from foraging oververy large distances. Observed migration and foraging rangesgenerally lie within the limits predicted by the models.