December 16, 2010

Bennett's Wallaby (Macropus rufogriseus)

Australia has some strange animals. Being an island cut off from the other continents and tucked away at the bottom of the world, Australia has seen evolution take a different approach. Where most mammals on earth are placentals (meaning that the baby develops in a placenta inside the mother’s body), in Australia the marsupial is the dominant mammal. Marsupials are born premature and crawl up into a pouch outside the mother’s body where they nurse and finish developing. Australia has many types of marsupials, but by far the most recognizable are the kangaroo and wallaby.

A wallaby is a close relative of the kangaroo, a bit smaller in size, but similar in all other aspects. The Bennett’s Wallaby, sometimes called the Red-Necked Wallaby, is native to Australia and Tasmania and is one of the largest breeds of wallaby. It is so large, in fact, that it is often mistaken for a kangaroo! Adult males can weigh up to 50 pounds and yes, they do have boxing matches. Males will box each other to determine breeding hierarchy; sometimes these boxing bouts will devolve into kick boxing matches. They have HUGE feet, and they are not afraid to use them. They belong to the “macropod” family, which literally means “big foot”. No kidding.

Wallabies have a unique way of getting around. They hop. Their giant feet look ungainly, but don’t let that fool you. When they get moving, they can be very fast and agile. They can easily outrun a human…or out-hop, as the case may be…

Wallabies live in loose groups called mobs. They are somewhat solitary, but they will gather together in groups to graze. Their favorite food is grass and leaves. They generally prefer open fields so they can spot danger more easily, but they will venture into forested areas looking for yummy leaves.

Like most marsupials, the lifecycle of the Bennett's Wallaby is quite interesting. They usually give birth in February and March, and always have only one baby. The Bennett's Wallaby is unique, because it is capable of halting the growth of an embryo; if an egg is fertilized before a baby, or "joey," is out of its mother's pouch, the female Wallaby can slow the growth of the embryo. Joeys are born after a gestation period of only a few weeks, when they are not yet fully formed. After birth, they crawl into their mother's pouch where they suckle for five to eleven months, until they are mature. The rate of growth of the Joey depends on the mother's diet: the better the mother's diet, the more nutritious her milk and the faster the baby grows.

Wallabies don’t have that much to fear these days, now that the Tasmanian tiger is no longer around to hunt them, but they do still fall prey to feral dogs and cats as well as the Tasmanian devil. By far, though, people are the wallaby’s biggest threat. They face a great danger from hunters and farmers who consider them a pest.

One rather interesting side note: Tasmania is the world’s largest producer of legally grown opium. It is grown for the pharmaceutical market. The problem, however, is that the wallabies don’t know this, and they have a habit of raiding the poppy fields and eating the crops. The farmers report gangs of wallabies who get “high as a kite” and then just hop around in circles. It is unknown at this point whether the authorities want to treat this problem as an illness or a crime…