Biodiversity

Wednesday, May 03, 2006

MEERKATS AND PRAIRIE DOGS

The meerkat or suricate (Suricata suricatta, Family Herpestidae) is one of Southern Africa’s best loved little mammals. They are social mammals that live together in underground burrows in a tight knit community usually called a gang, mob or band. They have a highly organized structure to their gang, with an alpha pair taking the leading role.(1) The alpha female is however not always the only breeding female in the group. If there is more than one breeding female, the births are synchronized, which makes caring for the young easier. (2)

They are said to have an altruistic lifestyle, looking out for each other. There is always a sentry or two on guard, while the others are out foraging for food, just playing or sunning them. (1) The sentry will stand up on its hind legs, often on top of a termite mound, keeping a constant watch for raptors and other predators. If danger is spotted, the sentry will give a warning bark and the others will run for cover to the closest entrance to their burrow. They are believed to have different barks for different messages, not only warning the rest of the mob if there is danger, but also letting them know that it is safe to continue foraging. (1, 2) Each individual is however also vigilant when out foraging for food. They will stand upright every few seconds to scan for danger and if satisfied continue their frantic digging for insects or reptiles. (2) If they are attacked, they will often gang up and try to intimidate the attacker by fluffing up their fur and with gaping mouths launch themselves as a unit at the attacker. (2)

The young are protected by babysitters, often young females, who without having her own babies will lactate and feed them, while the others are out foraging for food with the rest of the gang. (1,2) Once the young are big enough to venture outside, the babysitters will keep a close eye and stay close to an entrance. If danger is imminent and they do not make it to the burrow, they will even protect the young with their life by lying on top of them. (1)

They scent mark their territory frequently as neighbouring groups are hostile towards each other. Violent skirmishes between two groups can occur which intriguingly may be followed by a swapping of allegiances after the fight. This leads to new genes being added to the gene pool. (2) Mutual grooming serves to strengthen bonds and is part of their daily routine. Sometimes members of a group are separated for days and then grooming plays a big part in the welcoming rituals. (1)

Another Southern African mammal that lives together in a warren is the Cape ground squirrel (Xerus inauris, Family Sciuridae). Groups of up to 30 individuals are usually led by an alpha female. Only one mature breeding male is tolerated among the group of females. (3) They are vigilant and communicate constantly with each other through different calls, while out foraging for bulbs, roots, grass and the odd termite. (3) Their safety strategy is in their numbers and their constant communication. A very interesting reaction to an approaching snake has been recorded, where “the squirrel closest to the intruding snake will imitate the snake’s crawling motion by bringing its tail to the side of its body in a sweeping motion.”(3, page 128) This can thwart the attack as the snake gets so unnerved, that it moves away. (3) They also make use of the ‘babysitting system’ like the suricates and show similar social behaviour.

Some mole-rats are also social mammals, with the Damara mole-rat (Cryptomys damarensis, Family Bathyergidae) being the most social of all. (4) They live together in extensive colonies, reaching numbers that can exceed 40 individuals. (4) Because they live in a very arid part of Southern Africa, their biology is hugely affected by rainfall. The colony only has one breeding pair, with the rest being offspring that translate into a co-operative workforce. Many of the offspring never found their own colony and live a life of socially induced infertility, but this is their mean to survival as during the brief periods of rainfall, extensive digging must takes place to improve their burrow and to find enough food to store for the dry months ahead. (4) They eat bulbs, corms and tubers, many being toxic to other mammals. Their strategy to protect them from predators is living underground. Their nest site and food store can be as deep as two meters under the ground. (4)

Prairie dogs (Cynomis sp., Family Sciuridae) in the United States can be seen as the equivalent to the Southern African meerkat. They are also sociable mammals, living together in burrows. They can live together in much greater numbers than the meerkats and these big communities are called prairie dog towns. These towns once could stretch over a hundred square kilometres, but today, due to habitat loss their numbers have been much reduced. (5, 6)

The prairie dogs live together as a family unit of one male with a few females and their offspring. Many such family units live side by side, each respecting their neighbours’ territory and so forming a town. Once a burrow becomes too crowded, it is the parents that depart, establishing a new burrow at the edge of the town. The presence of neighbours is useful as the first to detect a predator will emit a sharp bark and the message is quickly conveyed from family to family alerting the whole town. They are also said to have sentries that keep a look out while the others are grazing. (6) Like meerkats they partake in mutual grooming and have a greeting ritual of “kissing”. (6) They also have a variety of calls that they use to communicate. (6)

The few examples of burrowing mammals I have mentioned have found safety in a tight knit social group, all with their own intricate rituals and a certain order in their respective communal societies.


Reference:
1. Wikipedia contributors. Meerkat [Internet]. Wikipedia, The Free Encyclopedia; 2006 Apr 28, 11:27 UTC [cited 2006 May 3]. Available from: http://en.wikipedia.org/w/index.php?title=Meerkat&oldid=50567374.
2. Hes L and Mills G. 1997. The Complete Book of Southern African Mammals. Pages 208-209 in Suricates by DW MacDonald. Cape Town. Struik.
3. Hes L and Mills G. 1997. The Complete Book of Southern African Mammals. Pages 128-129 in Cape Ground Squirrel by A Knight . Cape Town. Struik.
4. Hes L and Mills G. 1997. The Complete Book of Southern African Mammals. Page 123 in Damara Mole-Rat by J Jarvis. Cape Town. Struik.
5. Wikipedia contributors. Prairie dog [Internet]. Wikipedia, The Free Encyclopedia; 2006 May 2, 04:07 UTC [cited 2006 May 3]. Available from: http://en.wikipedia.org/w/index.php?title=Prairie_dog&oldid=51159074.
6. Reader’s Digest Editors. 1974. Animal Families. Marvels and mysteries of animal behaviour. Pages 141 and 151 in Animals in Action. Hong Kong: Reader’s Digest Association Far East Limited.

Karen Marais
BCB Hons NISL student
University of the Western Cape
Private Bag X17
Bellville

E-mail 2657211@uwc.ac.za

Web http://brit-journal.com/karen2006bcbnisl/

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