Rabbits Are Destroying Natural Habitats in Australia

Wild rabbit
Courtesy of John Loo

Australia has been home to one of the world's most destructive invasive species for more than a century–rabbits. Rabbits can annihilate plant species while causing soil erosion that drives native species out of their habitats. They eat a lot and reproduce prolifically, making them a major problem for Australia.

In 1859, 24 European rabbits were released into the wild in Australia for sport hunting. In only 67 years, their numbers increased to an estimated 10 billion. Rabbits propagate their species quite aggressively. Female rabbits can birth up to five litters, each containing 4-7 offspring annually. This means that it would take a single breeding pair of rabbits 1.5 years to increase the population by 182 rabbits. The consequences of this hyper-breeding is seen everywhere there are rabbits.

Rabbits are burrowing mammals. When their population gets out of control, this burrowing behavior damages the soil and causes soil erosion. They also have a habit of stealing burrows from other burrowing mammals, when they don't have enough to support their population. They are not only stealing the homes of these creatures, but they are making the land incapable of supporting these creatures in the future.

Another aspect of local eco-systems that rabbits destroy is the food supply, which is actually another cause of soil erosion. Studies show that it takes only two rabbits on one hectare of land to keep the plants on that land from growing. They are solely responsible for the near destruction of Hibiscus insutaris, a local plant. Rabbits are also guilty of a habit called ringbark. They use their teeth to remove the bark of trees in a ring around them. This effectively kills the tree. They also eat the little saplings, which keeps the trees from coming back. Other animals find it difficult to compete with the rabbits for food. Roughly 1/8 of all of the mammal species in Australia have been eradicated as a result of rabbit infestation.

All of this destruction is costing the Australian government hundreds of millions of dollars a year. Because of this and the destruction of native species, several attempts have been made to wipe out the rabbit population in Australia. (Animal lovers will not like their methods, but there is no denying that something needs to be done before more animals are made extinct because of this invasive species.) In 1950, the rabbits were given the myxomatosis virus in an attempt to reduce the population. It worked. Nearly 100% of all rabbits in Australia were killed. However, some of the rabbits became immune to the virus and the population became problematic again within a few decades. In the mid to late 90s the method was tried again with a new virus. This virus kills millions of the rabbits annually, but this is still not enough.

There are currently hundreds of millions of rabbits in Australia. This may not be as bad as the billions that once were, but if efforts to reduce the population cease for even a few years, billions of rabbits would appear again. It is a constant job to keep these rabbits in check and there is no end is sight.

Sources

Invasive Animals CRC, Rabbits, retrieved 3/15/10, invasiveanimals.com/invasive-animals/rabbits/index.html

The Effects of Rabbits on the Australian Environment, library.thinkquest.org/03oct/00128/en/rabbits/effect.htm

Animal Planet, Weird True and Freaky, Outback Rabbit Invasion

Antarctica's Blood Red Waterfall

Blood Falls is a natural feature of the Taylor Glacier in Antarctica. It is located in the McMurdo Dry Valleys at the edge of the glacier. It pours out of glacier and into Lake Bonney. Its waters are the color of blood, which is odd when you consider its surroundings. There is nothing else in the area that matches its color. The glaciers and lakes are your typical blues and whites and the valleys are brown where the wind has swept away the snow.

Scientists, researchers and explorers have been pondering the possible causes of the coloration of Blood Falls for some time now. Early on, they thought that the color might come from algae. However, algae have never been known to survive below a glacier, and Blood Falls’ source is beneath the Taylor Glacier. Then there is the fact that the water is very salty. In other words, it is seawater. What is blood red seawater doing pouring out of a glacier in Antarctica?

Barry Lyons of Ohio State University and a team of scientists did a decade long study of Blood Falls. At the study's conclusion, Barry’s answer to the mystery of Blood Falls was that part of Taylor Valley was once covered with a saltwater lake that had come in from Ross Sea. The iron in the water had settled to the bottom of the lake and was later picked up by the Taylor Glacier. Now the salty, iron-rich water is pouring out of the edge of the glacier. This next theory is based on basically the same principle, but it goes even further with the addition of something that may be even more interesting than the falls themselves.

In early 2009, Jill Mukucki from Dartmouth’s Department of Earth Studies released a paper regarding her research, and that of her colleagues, on Blood Falls. In this paper, Jill basically agrees with Barry Lyons about the source of the salt water beneath Taylor Glacier. However, the paper’s explanation of the color is largely different. Jill and her colleagues discovered microbes that live roughly 1,300 feet inside of the glacier. These microbes supposedly feed on the iron in the seawater under Taylor Glacier. By feeding on the iron, they help to break it down, which gives Blood Falls its red coloring.

These microbes may have had ancestors that were ocean life. They have apparently adapted to the lack of light (and many other things) within the glacier. They have utilized the only real resource in Taylor Glacier–the iron–and turned it into food. This is the first indication scientists have ever seen that life can exist beneath a glacier.

Sources

(Note: article has been updated. These are the original sources from 2010.)

Blood Falls, Antarctica’s Dry Valleys, retrieved 1/17/10, earthobservatory.nasa.gov/IOTD/view.php?id=35535

Unusual Antarctic Microbes Live Life on a Previously Unsuspected Edge, retrieved 1/17/10, nsf.gov/news/news_summ.jsp?cntn_id=114488

Inmar, Mason, April 16, 2009, Glacier “Bleeds” Proof of Million Year Old Life Forms, retrieved 1/17/10, nationalgeographic.com/news/.../090416-blood-falls.html