Science in the desert: Ethabuka Day 2 (afternoon)

on 03 May 2016 

Why walk when you can hop? Why hop when you can gallop?

Today we found a Spinifex Hopping-mouse (Notomys alexis) in one of the University of Sydney's pitfall traps on Ethabuka Reserve. Their long, narrow hind legs allow them to hop away from danger, and to dive down into their burrows. What a beauty!

The Spinifex Hopping-mouse is a mouse, not a marsupial – it’s a member of the order Rodentia. There are five extant (living) species of hopping-mice in Australia. Depending on the species, they can grow up to 27 cm from top to tail. Their tufted tail can be more than half of their body length! They weigh around 35 g, and their soft fur coat is grey, fawn or pale orange, with a white underbelly. When not hopping or ‘galloping’, they walk awkwardly on all fours.

Hopping-mice have dark eyes, strong front teeth and large round ears. Their ears have such a large surface area that the blood that flows through them returns to the body cooler than before, lowering their body temperature. This is a valuable adaptation for life in the arid interior.

Since European settlement, six species of hopping-mouse have become extinct. The five extant species have a patchy distribution in inland, central Australia. For most species, old records show a much wider, less fragmented range.

Hopping-mice live and burrow in the hummocks of plant species like canegrass and spinifex. Their burrows can be 1.5 m deep, 5 m long, with a series of chambers and entrances that they literally dive into! Hopping-mice are gregarious – a group of up to five individuals can live in one deep, humid burrow, protecting themselves from the daytime heat and huddling together in winter.

Hopping-mice are nocturnal. They rest in their burrows during the day, and venture out at night to forage. Hopping-mice don’t need to drink water – all the moisture they need comes from their prey. They eat seeds, berries, plants, insects, fungi and small reptiles.

They are opportunistic breeders. Populations of hopping-mice fluctuate greatly depending on rainfall and other environmental conditions. They can become locally extinct during times of drought, before their population ‘erupts’ after rainfall. Even though they’re little critters, they can migrate up to 15km towards rain! Without a pouch, young hopping-mice cling to their mother’s nipples.

The noise hopping-mice make is best described as a ‘twitter’. But, upon encountering a blockage in their burrow, they ‘squeak’ to enlist the help of other hopping-mice.