The Bilingual Frog (Crinia bilingua), known for its distinctive two-type mating call, is a small frog species found across north western and north-central Australia. As a species of least concern regarding its conservation status, AWC’s management is primarily focused on protecting the streams and intermittent swamplands that this species depends on for reproduction.
There are no known threats to the Bilingual Frog and there have been no recorded population declines, locally or nationally, which is why the species conservation status is listed as of ‘least concern’. It is worth noting that due to their reliance on ephemeral swamps and creeks for breeding, the species may become more vulnerable with changing rainfall patterns under a warming climate.
This small frog species grows to just 2.5cm in length and fully grown tadpoles are not much smaller. Tadpole colour varies from red, brown, or gold, while after the metamorphosis process have similar shades with more grey, brown, and green tones. Their underbelly is cream- or grey-coloured while their eyes have golden irises.
Adult frogs tend to have a triangular patch between their eyes and either dark patches or longitudinal stripes down their back. Their slender limbs are of moderate length relative to the rest of their body, and while the fingers and toes are unwebbed, their toes have a lateral fringe.
They are easily mistaken for other similar looking frogs with similar distributions including Crinia deserticola, Crinia fimbriata, and Crinia remota however the Bilingual Frog has a distinctly different call.
Due to their reliance on temporary swamps, pools, and lagoons for breeding, this frog species reproduces during the wet season (spring and summer). Males croak their mating calls between December and March, which as the name suggests, are two distinct calls – a high-pitched rattle or a musical clicking.
Eggs are laid individually or in small clusters underneath the water surface and attach themselves to available vegetation which typically includes grass stalks. The embryos hatch after approximately 80 hours and measure just 4mm long.
Tadpoles remain with these water bodies for about one month before the metamorphosis process occurs and they move out of the water. Tadpoles in warmer regions have been shown to develop faster, with metamorphosis occurring within 14 days.
Adults are typically shy and have an affinity for hiding in thick grass tussocks, making a sighting of this species quite rare.
Range and Abundance
This species is found across the Top End (Northern Territory) and the Kimberley Region (Western Australia), particularly in moist savannas, along intermittent rivers, and areas where water persists even through the dry season.
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