
Trials of Life
S01E09: Friends and Rivals
This installment investigates the ways in which those animals that live in social groups interact with each other. The solitary eagle is contrasted with whooper swans landing in Scotland after a 1,600-kilometre journey from Iceland. Once arrived, they must battle for territory with those already there, and pairs or families are usually victorious. Attenborough uses a group of farmyard chickens to demonstrate a pecking order. A pride of lions is shown co-operating to subdue a buffalo. Afterwards, each animal peacefully awaits its turn at the carcass. Baboons live in troops of up to 150, and their complex dominance hierarchy is examined in detail. Vampire bats display mutual assistance by regurgitating blood for any neighbour that has missed out on a night's feeding. Dwarf mongooses live in family groups of around a dozen. While some look for food or sleep, others are always posted on the lookout for predators and quickly raise the alarm if necessary. Meanwhile, some of the most extreme co-operation is demonstrated by the underground naked mole rat, whose 80-strong clusters are divided into workers (who tunnel perpetually), soldiers (who only act when danger threatens), and a single queen for breeding. Leafcutter ants are shown transporting their food deep below ground: it has to be planted in a special fungus to remove its indigestible cellulose, and each stage of the operation is carried out by a different caste of individuals.
Overview
Each of the twelve 50-minute episodes features a different aspect of the journey through life, from birth to adulthood and continuation of the species through reproduction.
Episodes


S01E02 Growing Up

S01E03 Finding Food

S01E04 Hunting and Escaping

S01E05 Finding the Way

S01E06 Home Making

S01E07 Living Together

S01E08 Fighting

S01E09 Friends and Rivals

S01E10 Talking to Strangers

S01E11 Courting

S01E12 Continuing the Line
Cast
