Hidden amongst the leaf litter and damp undergrowth of the Macedon Ranges lies a small amphibian with a striking appearance – the Brown Toadlet (Pseudophryne bibronii) 23. Despite its unassuming size, this terrestrial frog plays an important role in the local ecosystem and holds a significant conservation status.
The Brown Toadlet is a small frog, reaching a maximum body length of about 32 millimeters 23. Its dorsal surface typically ranges from brown to grey, often adorned with black spots or squiggles 23. While some individuals may have colored tubercles tipped with brown or orange, the most distinctive feature is its ventral surface, which exhibits a striking marbled pattern of black or grey and white 23. Adding to its unique coloration is an orange or yellow patch found on the upper foreleg, the back of the thighs on the hind legs, and sometimes on the groin and front of the thighs 23. A faded yellowish stripe may also run down the middle of its lower back 24. The skin on its back is generally smooth with a few scattered tubercles (warts), while the belly can be either smooth or slightly granular 24. Unlike many aquatic frogs, the Brown Toadlet’s toes are not webbed, and it primarily moves by walking 24. Interestingly, adult female toadlets tend to be slightly larger than males, measuring between 25-32mm compared to the males’ 22-30mm length 24.
The Brown Toadlet has a relatively wide distribution across south-eastern Australia, including Tasmania 24. Within Victoria, it can be found from the north-east through to central and western regions, with scattered records in Gippsland 24. Notably, recent surveys in the Macedon Ranges Shire have confirmed the presence of the Brown Toadlet at Bald Hill Reserve near Kyneton in 2016, a significant rediscovery as it had not been recorded in the area for over 20 years 24. This highlights the importance of ongoing monitoring efforts to understand the distribution of this species. The Brown Toadlet utilizes a wide variety of habitats, including dry forests, woodland, shrubland, grassland, coastal swamps, heathland, and even sub-alpine areas 24. They tend to inhabit areas that are likely to become inundated after rainfall 24. During drier periods, they seek shelter in damp areas under leaf litter, logs, or other forms of cover 24.
The diet of the Brown Toadlet primarily consists of small invertebrates. While specific details about their diet in the Macedon Ranges are not extensively documented in the provided materials, American toads, which are a related species, are known to eat worms, ants, spiders, mealworms, crickets, and slugs 25. It is likely that the Brown Toadlet has a similar diet, playing a role in controlling populations of small insects and other invertebrates in its habitat.
The breeding season for the Brown Toadlet occurs in autumn (March to May), when males initiate breeding by calling from their nest sites 24. Calling activity can begin as early as February and continue through August, with the most intense calling occurring on still evenings after rain in April to early May 24. Males call from within a burrow or nest, which is typically a concealed area under a rock or log, or within damp leaf-litter near water 24. The male’s call is described as a grating “ark” sound or a short, grating “cre-ek” noise, repeated every few seconds 24. Distinguishing their call from that of the Southern Toadlet is reportedly very difficult 24. Females are believed to reach reproductive maturity in less than two years and lay only one batch of eggs each breeding season 24. Eggs are deposited in the nest at the calling site or nearby in a concealed place near water, typically in loose clumps of 70-200 large, pigmented eggs 24. These eggs hatch when rain floods their area, providing the necessary water for the tadpoles to develop 24. Interestingly, if rain does not occur soon after laying, the eggs can survive unhatched for many weeks, and the tadpoles will begin to develop inside the unhatched eggs 24. The tadpoles themselves vary in color from dark brown to grey, with a clear tail fin mottled with black or brown flecks 24. This dependence on specific moisture conditions for breeding makes the Brown Toadlet particularly susceptible to changes in local hydrology and rainfall patterns.
Sadly, the Brown Toadlet is listed as Endangered (EN) in Victoria 6. It is also listed under the State Flora and Fauna Guarantee Act 1988, highlighting its precarious conservation status 6. Extensive habitat loss and degradation of waterways are considered major contributing factors to their decline in Victoria 10. Potential causes of habitat alteration and degradation include livestock grazing, cropping, infrastructure development, and previous and current mining activities 24. Waterway degradation, which impacts their breeding sites, can be caused by increasing salinity, high nutrient and sediment levels, invasive waterway weeds like willows, and changes to hydrology such as groundwater pumping and altered flow patterns 24.
The Brown Toadlet’s small size and marbled belly are key identifying features. Its terrestrial egg-laying behavior and reliance on rainfall for tadpole development are also notable. The Macedon Ranges Shire has undertaken surveys to monitor Brown Toadlet populations, with the rediscovery at Bald Hill Reserve being a significant finding 24.You can contribute to the conservation of the Brown Toadlet by supporting efforts to protect and improve the quality of their terrestrial and aquatic habitats. This includes participating in programs focused on pest plant and animal control and salinity reduction 24. Responsible land management practices that minimize habitat disturbance and maintain natural drainage patterns are also crucial. Reporting any sightings of Brown Toadlets to the Macedon Ranges Wildlife Network can help monitor their distribution and inform future conservation strategies. By understanding the unique needs of this tiny treasure, we can work together to ensure its survival in the Macedon Ranges.
