Social behaviour

Social groups

Many animals live in social groups and therefore exhibit behaviours that are adapted to group living

What are the three types of social groups?

• Cooperative hunting

• Social defence

• Social hierarchy

Social hierarchy

Animals living in large groups are influenced by signals given off by members of the group, meaning that individuals in a social group become organised in a graded rank order

What behaviours do dominant animals exhibit in their social hierarchy?

Ritualistic (threat) displays to reduce conflict

What behaviours do subordinate animals exhibit in their social hierarchy?

Appeasement behaviours to reduce conflict

Example: four dominant features in a wolf

• Bared teeth

• Raised body

• Raised ears and tail

• Wide eyes and staring

Example: four subordinate features in a wolf

• Covered teeth

• Eyes looking down

• Lowered body

• Lowered ears and tail

Example: social hierarchy

Pecking order in birds - one bird dominates and controls all the other birds by pecking them without being pecked in return, below the dominant bird is a second bird which can peak all the other birds except for the dominant one… etc

What is the advantage of a social hierarchy?

It increases the chances of the dominant animals desired genes from being passed down to potential offspring

Why do animals form alliances?

To increase their social status

Cooperative hunting

Some predatory animals cooperate with other members of the group to hunt prey

Under what circumstance does food sharing occur after cooperative hunting?

As long as the reward for sharing exceeds that for foraging individually

What are the five advantages of cooperative hunting?

• All animals gain more food than by foraging alone

• Allows larger prey to be caught

• Benefits subordinate animals as well as dominant ones

• Increases the chances of success

• Less energy is used per individual

Social defence

This increases the chance of survival for individuals in a group as many animals rely on ‘safety in numbers’ against predators who then find it more difficult to capture a member of a large, unpredictable group

What are two social defence strategies?

Formations - when under attack a group can adopt a specialised formation to protect their young and sentries - some individuals can watch out for predators while the others forage

Example: formations as a strategy for social defence

When a troop of baboons are moving, the dominant males stay in the centre close to the females and infants, while the lower ranking males keep to the edge of the troop to raise alarm if the group is threatened

Example: sentries as a strategy for social defence

To spot potential predators, adult meerkats will climb to a higher advantage point and stand on their hind legs, if they spot a predator they will use a certain type of alarm call to warn the rest of the group

Altruistic behaviour

Where one animal in a social group helps out another, harming the donor individual but benefitting the recipient(s)

Kin selection

Altruistic behaviour between a donor and a recipient if they are related

Why is kin selection likely to occur?

To increase the chances of the survival of shared genes in the recipients offspring

Reciprocal altruism

This happens if there is the prospect of an altruistic favour being returned at a later date, reversing the role of recipient and donor

Example: reciprocal altruism

Vampire bats will share their blood meals (regurgitate) with the hungry individuals that have fed them in the past

Social insects

Overtime complex patterns of social behaviour have evolved in some social insect societies where the division of labour means that different members of the social group have different roles to play

What are four examples of social insects?

• Ants

• Bees

• Termites

• Wasps

Example: social insects and their roles

• Workers - (sterile) collects nectar and defends the hive

• Drones - (fertile) reproduces

• Queen - (fertile) reproduces

Primate behaviour

Instead of producing many offspring to ensure that a few survive, primates have very few offspring and because of this take great care of them (high level of parental care)

Why do primates have long periods of parental care?

To teach complex behaviours to their offspring

What are the four major groups of primates?

• Lemurs

• Monkeys

• Apes

• Humans

What two types of complex social behaviours are learned at a young age in primates?

Ritualistic (threat) displays and appeasement behaviours

What are four major behaviours that support social hierarchies in primates?

• Body posture

• Facial expressions

• Grooming

• Sexual presentation

Body posture in primates

Subordinate males will bow low and look up at more dominant males while making soft grunting noises to appease them

Facial expressions in primates

Subordinate males will open their mouths and grin to more dominant males to appease them

Grooming in primates

This reduces tension in primate groups as one individual picks fleas, plant material, and scabs from the fur of another

Sexual presentation in primates

Females will show their rump for possible mounting and/or sniffing to reduce hostility

Survival value

Ritualistic (threat) displays reduce conflict, meaning weaker members are allowed to live in close proximity to more dominant members without the threat of hostility