At the Zoo: Southern Africa's Social
Diggers
by Kasey McCracken
Walking
through the Small Mammal House you may hear excited voices
exclaiming that they have spotted Timon from the Lion King.
These children (and frequently adults) have recognized the
slender-tailed meerkats (Suricata suricatta), or suricates
as they are sometimes called, from the popular movie in which
one is featured as a carefree drifter that travels with a
warthog. The animals' slender legs and silvery-brown, coarse
coats are helpful at making this recognition, but it is undoubtedly
their distinctive black eye patches and manner of sitting
upright on their hind legs that gives away their identity.
(Photo by Jessie Cohen/NZP)
This upright position might cause some to imagine that the meerkat is a type of prairie dog. In fact, this animal is not a rodent but a carnivore, and more specifically a mongoose, cousin to the dwarf mongooses (Helogale parvula) that also live in the Small Mammal House.
Meerkats live in the arid and savanna regions of Angola, Namibia, Botswana, and South Africa, and they occupy the driest habitat of all of the mongoose species. As communal burrowers, they either dig their own burrows or share burrows with African ground squirrels and yellow mongooses. Their home ranges generally include five burrow systems, or warrens, that they occupy in rotations of months or even years. Though warrens are often small and simple, with a few entrances, larger ones span areas up to 27 by 35 yards, and have as many as 90 entrance holes.
The Zoo's meerkats are relatively new to their current enclosure, a large exhibit that is almost entirely surrounded by glass. They lived in what is now the elephant-shrew exhibit, but this exhibit's flat, even terrain left the meerkats little opportunity to actively explore their surroundings. As a result, they often paced the limits of their enclosure. Before introducing the meerkats to the new enclosure, Zoo keepers completely changed the substrate, and it now contains a rocky and sandy terrain, similar to that found in meerkat habitat.
Meerkats have an incredibly diverse diet in the wild that includes many types of insects, and some lizards, birds, small snakes, and mice. Zoo keepers attempt to provide similar diversity by feeding the meerkats mealworms and crickets along with various types of meat. Unlike Timon in the movie, meerkats forage for their food in groups or pairs, and increase the chance of finding food by taking a different route every day. They find most of their food by digging among roots and under stones. At the Zoo, these activities, along with their tendency to burrow, mean that they turn over a lot of dirt throughout the day.
Small Mammals Animal Keeper Cathy Yarbrough placed rocks beneath the substrate throughout the exhibit to prevent the meerkats from burrowing too deeply. A buried T-configuration of PVC pipe provides a burrow for them beneath the sandy substrate, thereby reducing the necessity of burrow digging. Nonetheless, the meerkats still actively dig, which probably helps to keep their claws short, and early-morning visitors to the Small Mammal House can see Yarbrough daily attempting to fill in holes with substrate, followed by the meerkats undoing her work.
Meerkats, which live in groups of three to 30, are among the few carnivores that are highly social. Group-living may offer meerkats better defense against predators because, as a group, they can dig a more elaborate system of burrows with many entrances to escape danger. In addition, some group members act as sentinels when the group is foraging, standing on their hind legs to watch for predators and producing a warning call if they sight one. Another intriguing aspect of cooperative behavior among meerkats is that non-reproducing pack members act as helpers to guard and provision other meerkats' young.
On the other hand, despite their otherwise cooperative behavior, meerkats compete with each other for food; at the Zoo their feeding areas are widely spaced to avoid this problem. This food competition places a selective pressure on meerkats that they would not likely experience if they were solitary animals. Meerkats have been recorded teasing their offspring with food to encourage them to fight over it. This behavior may be a mechanism to cope with the selective pressures of sociality.
Unlike many other social animals, including the dwarf mongoose, meerkats do not appear to establish a linear hierarchy of individuals, and more than one pair breeds during the annual breeding season. The sexes do not have extremely different appearances, but the females are sometimes larger than the males and seem to be the dominant members of the group. Males appear to coexist quite well with one another, but when a female reaches sexual maturity, she is usually banished from the family.
The complexity
of the meerkat social system, along with the animals' tendency
to be highly aggressive toward non-pack members, have made
the task of integrating groups of meerkats extremely challenging
for Yarbrough and Associate Curator of Mammals Bill Xanten.
After the death of a male meerkat at the National Zoo in January
of 1994, the female here was left alone. Yarbrough had to
find creative means of getting the lone meerkat to eat because,
without a companion to watch for potential predators, she
was extremely nervous during feeding times.
Fortunately, two male siblings, named Fred and Barney, arrived
from the Philadelphia Zoo in December of 1994. The Philadelphia
males and the National Zoo female, named Pebbles, have now
formed a tight social group. They are extremely active, and
you can watch them foraging for food, resting, and grooming
together. Stop at the meerkat enclosure to admire the likable
creatures of Lion King fame. Once there, you may find watching
their various social activities even more entertaining than
the movie.
(ZooGoer 25(5) 1996. Copyright 1996 Kasey McCracken. All rights reserved.)
