Tammar is an extremely small kind of wallaby. It has predominantly dark, gray-brown fur, which becomes reddish on the sides and limbs. Its throat, chest, and belly range from gray to yellow. Tammars grow about 18 inches (45 centimeters) tall. Females weigh about 9 pounds (4 kilograms) and males weigh about 13 pounds (6 kilograms). Tammars live on a number of coastal islands, from the Abrolhos off the west coast of Australia to Kangaroo Island in South Australia. They also live on the nearby mainland, in forest and scrub country.
Tammars have a breeding feature known as delayed implantation. This means that if a female mates soon after giving birth, the resulting embryo remains in an early stage of development. If the young wallaby in the pouch dies or leaves, the embryo, or blastocyst, as it is called, resumes development and is born in normal fashion. The tammar can sustain the blastocyst for as long as 11 months, the longest period of any mammal.
