Social Behaviour Flashcards
What are the 3 types of social groups in animals?
Asocial
Social
Eusocial
Describe ASOCIAL animals
- have little interaction with conspecifics (members of same species)
- usually solitary for most of life
- may come together to reproduce
Describe SOCIAL groups
- Monogamous pair or polygamous groups (hierarchical) – alpha dominance
- can be unstable or stable groups
What is an example of a stable social group?
Wolf pack
Baboons
Lions
Chickens
= highly organised, stable.
What is an example of an unstable social group?
Shoal of fish
= movements, changes etc are all in flux - no hierarchical organisation
Describe a EUSOCIAL species
- highly social
- labour is divided
- sacrifice of reproduction is often made to benefit whole group
Give some examples of eusocial species
Bees
Naked mole rats
ants
termites
Name 3 advantages to group living
Any: – Heat (thermoregulation) – Predator avoidance – Predator protection – Defence – Feeding – Locating food – Defence of prey – Reproduction and mating systems
Name 3 disadvantages to group living
Any from: – Increased competition for food – Increased disease transmission – More obvious to predators (pheromones) – More risk of parasitism/cannibalism of young – Reduced reproductive success
How does group living reduce risk of predation
o More eyes can detect a predator earlier = more vigilance (meerkats)
o As group size increases, individuals can decrease own vigilance
o Spend more time foraging and/or save energy
- groups can also confuse predators (zebras)
- communal defence
Give an example of when group living reduces predation risk
Meerkats (Suricata suricatta) - have a sentinel to look out for predators and warn the group
Zebras - confusion defence from markings
Give an example of predator confusion in social groups
zebras - groups stripes confuse predators
Give an example of increased predator vigilance
birds flocking
Meerkats: Suricata suricatta
Give an example of communal defence
Buffalo grouping to defend against an attacker
How do Harbour seals show increased vigilance in groups?
When they haul out offshore sandbanks/ beaches, scanning behaviour is observed to look out for predators.
The bigger the group, the more time spent scanning
What are sentinels
They act as look-outs and signal alarm calls in presence of danger
Give an example of a sentinel
Meerkats
What did Bedenkoff (1997) conclude about unselfish behaviour (4 points)
o Individuals more likely to become sentinels when satiated
o Sentinels detect predators first and also flee first (increased survival)
o Sentinels change in the group as the sentinels become hungry and are replaced by foragers
o Observations that even solitary individuals become sentinels when satiated
What does the presence of pups cause in meerkat behaviour?
When on foraging trips, both male and female meerkats increase sentinel behaviour when pups were with them.
Consequently, females found less food (because more time spent on look out)
What is the dilution effect?
The dilution effect is the idea that the chance of an individual being captured by a predator decreases as group size increases. This is because the predator only takes a single or a limited amount of prey in each attack
How do you calculate an individuals risk of predation, according to the dilution effect?
1 individual = 100%
10 individuals = 1/10
12 individuals = 1/12
n = group size risk = 1/n
What is the selfish herd effect/ principle? (Hamilton, 1971)
the idea that each individual in the herd will try to be at the group centre to avoid predation.