Frogs galore (and mice) at Eurardy

With small animal monitoring currently happening at Eurardy Reserve in cooler weather than previous years, we’ve seen a shift in the species we might normally expect to catch.

As opposed to our usual suite of reptiles, we’ve had much higher numbers of small mammals. These include some of Eurardy’s cuter residents such as the Ash-grey Mouse (Pseudomys albocinerus), a small pretty rodent with soft grey and white hair that lives underground in the heathland at Eurardy, and the iconic Spinifex Hopping Mouse (Notomys alexis) a larger rodent with big back feet, large ears and a tufted tail.

However, after a small amount of rain, the real stars of the show this year were the frogs.

Eurardy sits in the semi-arid zone with highly variable rainfall averaging only around 310 mm a year. With no permanent water sources, you might not expect to find many frogs here. In fact, a large number of Australian frogs have evolved to cope with our mostly dry climate.

You can find quite a few species of frogs on Eurardy, all of which have evolved to bury themselves into the ground, and often go into a state of aestivation where their metabolic rate decreases and they sit dormant until it rains again.

When it rains, some species take advantage of ephemeral water bodies to breed. Others lay their eggs in burrows which should eventually flood and some species lay eggs that develop directly into frogs and skip the tadpole stage altogether.

This year at Eurardy we caught Humming Frogs (Neobatrachus pelabatoides), Plonking Frogs (Neobatrachus wilsmorei), Western Spotted Frogs (Helioporus albopunctatus) and Crawling Toadlets (Pseudophryne guentheri).

However, the most exciting capture this year was the Southern Sandhill Frog (Arenophryne xiphorhyncha).

These cool little frogs were only described as a species in 2008. Previously they were thought to be a southern population of Sandhill Frogs (at the time a monotypic genus) until genetic work revealed that the populations had diverged somewhere between five and seven million years ago.

As a result they were classified as two different species; Northern and Southern Sandhill Frogs. Southern Sandhill Frogs are only about 3.5cm long, they have short legs and a flattened rounded body adapted for burrowing through the sand. They have a limited range from north of Geraldton to south of Shark Bay and although they're presumed to be very similar to Northern Sandhill Frogs, not a lot is known about them.

As well as being an exciting animal to find and see, this record is a first for Eurardy. Previously the closest known location was 40km away so it’s quite exciting to trap two individuals on Eurardy at sites some distance apart.