The Bunny Invasion

Australia is trying to kill all the bunnies that have invaded it, and all for environmental conservation. This seems counterintuitive, but ever since rabbits were introduced more than 150 years ago, they have been wreaking havoc. Rabbits are what we call an invasive species. They were introduced as “hunting fodder”, but their population quickly increased to about 10 billion! Today, rabbits are huge economic crisis- they eat crops worth about $206 million every year. They also cause great harm to the environment. For example, they have caused the populations of native plant species to decrease drastically. The populations of other small mammals were not able to compete with rabbits and so their numbers went down as well. Rabbits create networks of burrows, which loosens the topsoil and causes erosion. These problems were seen to diminish since 1996, which coincides with the introduction of RHDV.


The rabbits in Australia, Oryctolagus cuniculus. Image Credit: PsJeremy via Flickr.

RHDV is sort of a miracle virus, a result of years and years of trial and error. At first, hunting and fence building were used to control and contain rabbit populations. These tended to be ineffective because the population size was just too big to be controlled this way. Introducing viruses to kill the rabbits was originally Louis Pasteur’s idea, but it wasn’t until several decades later that a truly effective virus was found. This is because the rabbit populations were large enough to be resilient to viruses, since they reproduced so fast and had to be quickly infected for any substantial effects on the population size. Scientists had to find something that would be difficult for a rabbit’s immune system to deal with. The release of the the myxomatosis virus in 1937 caused a drastic decrease in the rabbit population from 600 million to 100 million by the 1950s. However, in a few years, the rabbits developed resistance to this virus.  This caused the population to start increasing again, however, it never reached the sizes pre-1950. In 1996, the Rabbit Hemorrhagic Disease Virus (RHDV) was released, and proved to be very effective. Rabbits still haven’t shown a resistance to RHDV, because this virus causes quick mortality. On March 10th of this year the first rabbit was found dead from the K5 virus, a new and improved strain of RHDV which was developed after about a decade of research.


Releasing rabbits infected with myxomatosis into the wild in 1937. Image Credit: CSIRO via Wikimedia Commons. 

The spread of invasive species has far reaching consequences, not just on our economies but also on the existing ecosystems of an area. It seems drastic and dangerous to introduce a virus into the environment. It will reassure you to know that this virus does not affect humans. The only concern some people have is that it will affect their pet rabbits, but vaccines exist for this purpose. Spain and other European countries, where wild rabbits are endangered, worry about the accidental introduction of the K5 strain into their wild populations. In Australia, however, other species are being faced with the threat of extinction due to the issues caused by the rabbits. Innovative techniques like these, and research about where our priorities with conservation lie, can really help us figure out how to best conserve the ecosystem as a whole.

About the Author

sonnySunishka “Suni” Thakur is an undergraduate at the University of Georgia majoring in Genetics, currently just trying to make the most of her freshman year. She loves to read, dance, work with student organizations like First Book and World Ambassadors, and gets very excited about science. More from Sunishka Thakur.