Giant Burrowing Frog

Details

The Giant Burrowing Frog (Heleioporus australiacus) is a large, robust ground-dwelling frog endemic to south-eastern Australia. As its name suggests, it is highly adapted to a burrowing lifestyle, spending much of its time underground and emerging mainly at night and during wet periods to feed and breed.

Taxonomy & Names

• English name: Giant Burrowing Frog

• Scientific name: Heleioporus australiacus

• Family: Myobatrachidae (Australian ground frogs)

• Genus: Heleioporus

Appearance

The Giant Burrowing Frog is one of Australia’s larger burrowing frog species:

• Body size: adults typically reach about 7–10 cm in length, with females often larger than males;

• Build: a stocky, broad-bodied frog with a large head and powerful limbs;

• Dorsal colour: grey-brown, olive-brown or dark brown with darker mottling and spots that blend with soil and leaf litter;

• Skin texture: the dorsal skin is slightly rough with small warty bumps and prominent glandular ridges along the sides and limbs;

• Belly: underside is usually whitish or pale grey with bold black or dark marbled markings;

• Eyes: relatively large, often with a golden or copper-coloured iris;

• Feet: strong hind limbs with well-developed toe webbing and a large inner metatarsal “spade” or tubercle used for digging.

Distribution & Habitat

The species is endemic to south-eastern Australia:

• occurs mainly in parts of New South Wales and Victoria;

• associated with higher rainfall areas in forests, woodlands and heathland, often on coastal ranges and nearby uplands.

Giant Burrowing Frogs favour habitats that combine suitable soils for burrowing with access to streams and temporary water:

• moist eucalypt forests, heathy woodlands and shrublands;

• gullies, creek lines and valley slopes with sandy or loamy soils;

• areas near small streams, seepages, roadside drains and temporary pools used for breeding.

Behaviour & Burrowing

The Giant Burrowing Frog is a nocturnal, fossorial (burrowing) species:

• by day it typically remains in burrows dug into soft soil, often on slopes or banks above streams and soaks;

• burrows are usually concealed by leaf litter, roots or rocks and provide a cool, moist refuge;

• frogs emerge mainly at night, particularly during or after rain, to forage on the ground and along stream margins;

• during extended dry periods they may remain underground for long stretches to reduce water loss.

Call

Male Giant Burrowing Frogs produce a low, resonant call during the breeding season:

• the call is often described as a drawn-out “whooomp” or deep “oomp” note, repeated at intervals;

• males usually call from burrow entrances or from concealed positions close to streams and pools;

• in suitable habitat, the calls of several males can echo through gullies on wet nights.

Diet

The species is carnivorous and feeds mainly on ground-dwelling invertebrates:

• beetles, crickets, cockroaches and other ground insects;

• spiders, slugs and various other arthropods and soft-bodied prey;

• occasionally it may take small frogs or other suitably sized vertebrates.

Giant Burrowing Frogs hunt at night, moving slowly across damp ground and lunging at prey detected by sight and movement.

Breeding & Life Cycle

Breeding in the Giant Burrowing Frog is tightly linked to heavy rain, stream flow and temporary pools:

• breeding generally occurs in warmer, wetter months, often following substantial rainfall;

• males call from burrows or from close to water along streams, soaks and temporary pools;

• females lay eggs in foamy egg masses created within burrows or in very shallow water at the edges of pools;

• when water levels rise or streams flood, the foam nests are inundated or washed into shallow pools where tadpoles continue development;

• tadpoles grow in slow-flowing sections of streams or temporary pools, and after metamorphosis the young frogs disperse onto land and begin a burrowing lifestyle.

Conservation Status & Threats

On the IUCN Red List the Giant Burrowing Frog is listed as Vulnerable (VU), reflecting ongoing threats and declines in parts of its range.

Major threats include:

• habitat loss and fragmentation from forestry, agriculture, roads and urban development;

• alteration of natural flow regimes through dams, water extraction and drainage works, which disrupt the flooding and      temporary pools required for breeding;

• degradation of water quality from sedimentation, pesticides and other pollutants;

• potential impacts from amphibian diseases such as chytrid fungus and from long-term climate change affecting rainfall patterns.

Conservation efforts focus on protecting forested catchments and streamside vegetation, maintaining natural flow patterns where possible, and reducing pollution and land clearance in key breeding areas.