Australasian Science: Australia's authority on science since 1938

Kangaroos Eating Reptiles out of House and Home

Large numbers of kangaroos are destroying the grassland habitats of reptiles, according to research published in PLOS ONE.

“When there are too many kangaroos, they overgraze grasslands until they are like a lawn, which leaves lizards with no shelter,” said Australian National University PhD student Brett Howland.

The study found that in areas where the grass was higher than 20 cm there were more than twice as many reptiles, and nearly three times as many species of reptile, than when grass was short.

Lizards depend on grass cover for both food and shelter, and are an important part of the ecology – they provide food for birds and small mammals, and provide pest control by eating insects.

Without threats from indigenous hunters and native predators such as the dingo, kangaroo numbers have skyrocketed. “The current number of kangaroos in some of Canberra’s parklands, over 300 per square kilometre, removes all tall grass,” Howland said. “We should be controlling kangaroo numbers to at most 100 kangaroos per square kilometre in grasslands on average, and even less in treed areas.”

“Many reptiles are under threat – species such as the striped legless lizard are on the vulnerable list. They face possible extinction in the near future,” Howland said.

“However, there are millions of eastern grey kangaroos in Australia, making them one of the most populous large mammals in the world.

“Just because kangaroos are native doesn’t mean they don’t do damage. We have to regulate their numbers if we want to retain a variety of reptiles,” he said.