GEOLOGY

Detailed explanation-1: -Animal migration is usually considered to be instinctive.

Detailed explanation-2: -The migratory instinct is heritable, the urge to travel switched on by hormones triggered by changes in day length.

Detailed explanation-3: -Migration is an innate behavior characterized as the long-range seasonal movement of animals; it is an evolved, adapted response to variation in resource availability.

Detailed explanation-4: -For example, salmon start life in rivers and migrate to the sea to feed and grow. After spending up to seven years in the ocean, they migrate back to the rivers they were born in so that they can spawn. Christmas Island red crabs (Gecarcoidea natalis) migrate for similar reasons.

Detailed explanation-5: -migration, in ethology, the regular, usually seasonal, movement of all or part of an animal population to and from a given area. Familiar migrants include many birds; hoofed animals, especially in East Africa and in the Arctic tundra; bats; whales and porpoises; seals; and fishes, such as salmon.