A Gerbil is a small mammal of the order Rodentia. Once known simply as "desert rats", the gerbil subfamily includes about 110 species of African, Indiam, and Asian rodents, including sand rats and jirds, all of which are adapted to arid habitats. Most are primarily diurnal (though some, including the common household pet, do exhibit crepuscular behavior), and almost all are omnivorous.
One Mongolian species, Meriones unguiculatus, also known as the Clawed Jird, is a gentle and hardy animal that has become a popular pet. It was first brought to the United States in 1954 by Dr. Victor Schwentker for use in research.
Gerbils are typically between six and twelve inches (150 to 300 mm) long, including the tail which makes up approximately one half of their total length. One species however, the Great Gerbil, or Rhombomys opimus, originally native to Turkmenistan, can grow to more than 16 inches (400 mm) in length. The average adult gerbil weighs approximately 2 1/2 ounces. As of August 19, 2003, officials in western China's Xinjiang Uygur Autonomous Region began releasing eagles to combat the damage they say the great gerbils have done to eleven million acres (46,000 km²) of grassland.