The Mongolian gerbil, the most common species sold in stores, is a born burrower and will develop networks of tunnels with food storage, nesting, and sleeping sites. Gerbils are 4 to 6 inches long excluding the tail and have a life span of 3 to 5 years. Over the years, some two dozen hybrids and color variations have been developed. The original brown or gray coated animal now comes in black, lilac, chocolate, cream, nutmeg, blue, among other colors, some with red eyes, some with black. Some rarely imported species, small Egyptian gerbils, Indian (pink-footed) gerbils, and Libyan gerbils known as jirds, now appear in shops. All are gentle, hardy pets.
For more information, please read Choosing a Gerbil