Compelling photographs from a long term study on meerkats in the Kalahari, Southern Africa have been released by researchers as part of their study on how ageing affects reproduction in animals.
Scientists have previously thought that death rates are so high in the wild that ageing rarely occurs. This is the first research that tests how ageing affects wild animals that breed cooperatively.
Meerkats are desert dwelling mongooses that live in social groups containing a dominant male and female. Subordinates in the group rarely have their own young, instead helping the dominant meerkats to breed.
The recent study reveals that contrary to what was previously predicted, breeding success in dominant females decreases dramatically with age, despite the help provided by subordinates.
Breeding success starts to decline early compared with other vertebrates. One explanation is that maintaining dominance, which can involve aggression, is costly and gets harder with age, affecting breeding success.
All individuals are closely monitored from birth to death. The animals are habituated to humans, allowing scientists from the University of Cambridge's Kalahari Meerkat Project to follow them from a few metres away without affecting their behaviour.
At least one individual in every group is fitted with a radio collar so the animals can be tracked. Every individual is uniquely marked with dye so it can be easily identified in the field.
Every day, a team of researchers collects life history and behavioural data from all of the individuals in the population. Habituated animals can be weighed three times a day to assess foraging success, growth and condition.
Professor Tim Clutton-Brock set up the Kalahari Meerkat Project in 1993, which studies 10-15 meerkat groups in the Northern Cape, South Africa. He and Dr Stuart Sharp publish their new findings in the Journal of Animal Ecology.
Subordinate helpers assist the dominant breeders in various ways. They baby-sit young pups in the burrows where they are born and continue to protect them when they first join the group above ground.
Helpers provide the pups with food, including millipedes, scorpions and small reptiles, until they are around three months old and able to feed themselves. This young pup has been given a lizard to enjoy.
Meerkats spend a lot of time on guard and they have superb eyesight, spotting predators from a great distance. They give distinctive alarm calls to warn the rest of the group.
This is a dominant male named Zaphod. At 11 years old, he is the oldest male in the population. Continuing to monitor individuals like Zaphod holds the key to further understanding the process of ageing in wild social animals.
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