The fluffy European rabbit is a major pest, particularly in Australia where they have swept through the landscape, decimating wildlife and becoming the most significant factor of species loss in the country. But regions thought to be safe from the cotton-tailed critter are safe no more, as the rabbits are now able to eat the eucalyptus leaves originally thought to be too toxic.
Reported in the journal Australian Mammalogy, the new adaptation by the lagomorphs means that they can survive in regions devoid of grass but rich in eucalyptus, such as the Snowy Mountains of New South Wales during wintertime. How they manage to digest the leaves, which require special adaptations by the native wildlife, is still unknown, as are the potential environmental impacts of the rabbits on the ecosystem.
Rabbits have been a massive problem for the native wildlife of Australia. Introduced in 1788 with those who founded the first European colony in the country, they were originally transported to the settlement for food and kept in cages, before being bred in larger enclosures. Incredibly, it is thought that the current invasion can be traced back to just 24 wild rabbits released in the state of Victoria in 1859.
Through a combination of reduced native predators, natural selection, and the hybridization of domestic and wild rabbits, the lagomorphs boomed in the country. The mild winters meant the animals could breed all year round, while the destruction of native forests for agriculture and grassland gave them all the food they needed. The result was the fastest spread ever recorded of any mammal in the world.
The effect on the native flora and fauna has been devastating. The rabbits decimate local vegetation, stripping trees of bark and turning the landscape into something reminiscent of a golf course. This increases the weathering of the land, as wind and rain rapidly remove the topsoil that can take hundreds of years to form. This has a knock-on effect to the local wildlife that call these regions home, as there becomes little left for them to survive on.
And it now seems that the pesky critters are able to live in regions once thought impossible. It used to be thought that everything above the snow line of the Snowy Mountains was a rabbit-free range. The snow cover during winter months prevented the animals from getting a foothold as it prevented the rabbits from feeding on grass. In 2011, however, scientists began to notice them moving in. It now seems that they are feeding on the low-growing leaves of new saplings, which is getting them through the harsh winters until the snow cover melts.
Even in their native Europe, the rabbits don’t live above the snow line all year round, so how they will respond to the novel environment is still completely unknown. But if recent history is anything to go by, it may not be looking so rosy for the native animals that call the mountains home.
[H/T: New Scientist]