The Mongolian Gerbil, Meriones unguiculatus, is a common pet, but its life in the wild is anything but “common”. In fact, its social structure and breeding habits are among the rodent world’s most unique. Let’s take a look at what field research has revealed about this most interesting little creature.
What are Gerbils?
Mongolian Gerbils, sometimes known as Clawed Jirds, are classified in the rodent subfamily Gerbillinae. Within this group are over 115 species of African and Asian gerbils, jirds and sand rats, most of which are adapted to life in deserts, steppes and other arid, open habitats.
They range in size from the 5-inch long Henley’s Gerbil to the Great Gerbil (please see photo) and the Indian Red-Footed Gerbil, which approach 18 inches in length.
Mongolian Gerbils are highly sociable animals, and live in colonies consisting of 1-3 males and 2-14 females. Colony members cooperate in gathering and storing food and also chase off intruding gerbils and small predators. Winters are spent together in a communal burrow.
A “Mating Holiday”?
Biologists studying wild gerbils wondered how inbreeding (mating with relatives) was avoided, because strange gerbils are not tolerated, and individuals remain in the same colony for their entire lives. Studies revealed that the gerbils have evolved a most interesting strategy to prevent the problems associated with inbreeding (birth defects, loss of genetic diversity, etc.).
It seems that female gerbils “sneak off” and visit neighboring colonies to mate with unrelated males. They then return to their home colony and also mate with their regular partners (Mongolian Gerbils tend to form stable pairs within their colony). Baby gerbils are, therefore, raised by their mothers and “uncles”, not by their fathers.
A few questions arise – why are “visiting” females tolerated in neighboring colonies? Also, I wonder if females mate with their stable partners in order to “trick” them into raising offspring that are not their own (as seems to happen in some bird species) or if litters are fathered by 2 or more males?
I find it very exciting that such basic questions remain about such a commonly-kept pet. Great opportunities to contribute to what we know are open to gerbil owners, especially if you can set your pets up in a large, naturalistic enclosure (please write in if you would like further information).
Other Unique Mating Behaviors
As male gerbils mature, some remain with the colony while others are chased off by the older males. Amazingly, studies have shown that the most fertile young males are the ones that are expelled from the colony (no sense in keeping strong competitors nearby, I guess!).
Also, female gerbils that remain in their mother’s colony take longer to reach sexual maturity, and bred less frequently, than do females that leave the colony. They bred regularly, however, if the mother dies or is removed. In some colonies, competition results in a single dominant female being the only breeder.
All in all, a most interesting and unique rodent! The history of the Mongolian Gerbil’s discovery and entry into the pet trade also has many unexpected twists and turns. Please see the article below for the fascinating story.
Video: Gerbil avoids crashing its exercise ball
Wild Mongolian Gerbil image referenced from wikipedia and originally posted by Alastair Rae
Baby Mongolian Gerbils image referenced from wikipedia and originally posted by Dawson