The impact of fire history on Autumn breeding frogs in the Otway’s National and Forest Park

The impact of climate change on bushfires is predicted to completely transform fire regimes resulting in strong ecological disturbances in many wildlife systems, and a huge stress across many taxa. Despite being the most declining vertebrate group, amphibians are underrepresented in fire ecology research. Amongst these Pseudophryne semimarmorata a small toadlet endemic to south-eastern Australia, is particularly under-researched. P.semimarmorata are anecdotally in decline throughout Victoria, but due to lack of research, particularly in the Otway’s, a population status is not determinable and thus proper assessment in management practices not possible. The aim of this project was to determine the impact of fire history and other environmental variables on P.semimarmorata and other autumn calling frogs in the Otway’s national and forest park.73 sites were surveyed overall. Twenty-three sites were surveyed using Song Meter SM4 Acoustic Recorders, which were placed on the western end of the park, and 50 on the eastern end using 15 minute callplayback surveys. Detection and occupancy modelling were used to determine the impact of survey covariates (temperature, humidity, in situe wind and maximum wind and rainfall) and site covariates (vegetation structure, time since fire, number of fires and road density) on the detection and occurrence of P.semimarmorata and other frogs heard. Overall, we were able to test the impact of fire on 3 frogs: Pseudophryne semimarmorata, Geocrinia victoriana and Litoria ewingii. P.semimarmorata and G.victoriana had a significantly negative relationship with roads, and L.ewingii was significantly impacted by vegetation structure showing a preference for canopy cover and leaf litter. None of the frogs showed a significant relationship with fire, but L.ewingii and G.victoriana did show a slight increase in occurnece probability as time since fire increased, and P.semimarmorata did show strong increase in occurrence probability during the first 5 years after a fire, which
eventually evened out. A more long-term study with a larger sample size should be conducted 4 to increase statistical power and allow a deeper exploration into landscape relationships such as roads, fire history and frog occurrence, particular in P.semimarmorata.