Waterfall Frog

Waterfall frog

Scientific name: Litoria nannotis

Conservation status: Endangered

The Waterfall Frog is a large frog that reaches up to 6.5cm in body length. They are a light brown, olive-green or grey frog with a white belly. The iris is golden with black flecks, the males have black nuptial spines on the base of their thumbs to help grip females.

They are a species that dwells in streams and endemic to the Wet Tropics of Australia. They are usually found in rocky streams where there is fast flowing water, waterfalls and cascades. Unlike other frogs that use streams for breeding the Waterfall Frog uses streams as their primary habitat.

They are found throughout the Wet Tropics Bioregion, North Queensland, Paluma to Cooktown, but only has stable populations in lowland sites. They used to be found in locations of 1300m altitudes but that has been steadily declining since the 1990s, some surveys as recent as 2013 has started to find them in more upland areas. The decline has occurred mostly due to the amphibian chytrid fungus.

They have distinctively different diurnal and nocturnal behaviours. In the daytime they are restricted to the streams or find shelter in small refuges that are behind waterfalls or can be found wedged between rocks in the stream. Waterfall Frogs can sometimes be found basking in the splash zones next to the waterfalls. During the night they are far more active. They often will be found in more exposed locations in the stream or sometimes can be found in the vegetation alongside the stream. The males can sometimes be spotted participating in foot flagging displays; however, this is the most common form of communication since sound doesn’t travel due to the waterfalls and running water. When breeding they will attach their eggs under rocks in the stream.

Their diet consists of terrestrial and aquatic invertebrates, this includes flies, dragonflies, beetles, cockroaches, ants, millipedes and other bugs that get close to the stream. Tadpoles feed on algal-covered rocks in the flowing streams.

The Waterfall Frog currently is considered an Endangered species due to a steady decline in numbers. The continued decline in numbers has not been attributed to natural disasters such as, drought, floods or human based intervention such as habitat destruction, pollution from pesticides or inorganic ions and heavy metals. The habitats of the Waterfall Frog have been a protected region since 1988 so habitat destruction is no longer of concern for causing more loss of the current population. Some research thinks UV-B light could be having an affect on the population but no confirming evidence has been found.

Chytridiomycosis due to chytrid fungus or a viral infection is considered to be the likely cause of numbers declining as it has been observed in many Waterfall Frogs that have been captured for research into the possible cause of the population decline.  Since the Waterfall Frog doesn’t have the same protective skin as some other frogs found in the same region, they can’t protect themselves from the disease. Feral pigs have also increased in number but the effect they have had on the Waterfall Frogs habitat is currently unknown.