The Influence of Climate and Livestock Grazing on Two Species of Burrowing Desert Frogs

ABSTRACT Frogs are one of the most vulnerable groups of vertebrates globally, occupying a range of environments including arid deserts. They are threatened by many interacting factors, including climate change and livestock grazing. In this study, we present the first long‐term research (over 30 years) on two arid‐dwelling frogs in Australia, the trilling frog ( Neobatrachus sudellae ) and desert spadefoot frog ( Notaden nichollsi ), assessing the influence of climate and grazing on their above‐ground activity and body condition. We found that rainfall was positively associated with captures of both species but higher rainfall totals in the 7‐days prior to trapping had a stronger positive effect on Neobatrachus sudellae , whilst higher rainfall in the 30‐days before trapping, alongside the week prior, had a stronger influence on Notaden nichollsi . Both frogs responded variably to temperature, overall exhibiting no strong trends. Surprisingly, the body condition of both species also did not differ strongly across higher or lower values of rainfall or temperature. However, the two frogs differed in response to livestock grazing, with Neobatrachus sudellae captures increasing at sites that had grazing removed, whilst those of Notaden nichollsi declined after grazing removal. Livestock grazing had little effect on Neobatrachus sudellae body condition and weak, though positive, effects on Notaden nichollsi . We suggest that the increased susceptibility of Neobatrachus sudellae to grazing may arise because this species burrows in sites that are more likely to experience high cattle activity and because their shallower burrows render them more susceptible to trampling effects than do the deeper burrows excavated by Notaden nichollsi . Such differences between the species with respect to livestock grazing may reflect tolerance to disturbance. We conclude that impacts of livestock grazing on frogs are species‐specific but may interact with climatic change to threaten arid‐dwelling species and propose that further study of the effects of these variables on other frog species is needed.