Cooperative Interactions - Group Formation

These are several types of grouping in animals, grouped under two main types

a) Family formation and

b) Aggregations.

a) Family formations

Purpose of reproduction leads to the formation of groups of individuals, called a family, which is an instinct of individuals of different sexes of a species.

However, grouping behaviour varies from one species to another.

i) Some animals are solitary and lead more an independent life. Adult males and females come together only for a short period for mating.

Examples: Tigers, owl, hamsters, insects etc.

ii) Some animals lead lifelong family life with once paired male or female, continue their companionship throughout their life. Such animals are referred as 'monogamous'.

Examples: Foxes, wolves, swans, parrots, gibbons etc.

iii) Some animals are 'polygamous' i.e., a single male keep a group of females (referred as 'harem'), and the male may mate with any of these females during the breeding season. In such groups, the family unit is dominated by the male individual.

Examples: Walruses, deer, zebras, seals etc.

iv) Few animals such as sparrows and chickens show seasonal partnership, and the male and the female find new partnership in every breeding season.

v) Certain animals such as rats and mice show no fixed type of partnership.

b) Aggregations

It is a cooperative intraspecific interactions in which a number of solitary animals aggregate at the time of some particular activity. Such animals are referred as gregarious animals.

The aggregations may be a temporary or permanent ones.

Examples:

i) Temporary aggregations are found in frogs. They form groups only during breeding season.

ii) Many solitary birds aggregate during migration, and hibernation is the cause for aggregation in snakes.

iii) Permanent aggregations are found in flocks of sheep, goats, birds, 'swarms', of insects, shoals of fish, prides of lions, troops of monkeys, herds of deer, zebra, elephants etc.

A herd is formed of members of a single family, which comprises of adult male, female/s and their children. Variations are seen from this pattern like herds of African elephant constitute only females and their offsprings.

Mixed multiple herds are also observed in few animals like that of mountain gorilla, olive baboon and macaque.

Significance of aggregations

1) Increase chances of sexual reproduction, locating food, protection from predators.

2) Members show specialization in performing specific functions.

3) Transfer of knowledge about food capturing and defence from predators happens, from parents to offsprings, which becomes an essential learning for survival.