Climate-driven variation in food availability between the core and range edge of the endangered northern bettong (Bettongia tropica)

The endangered northern bettong (Bettongia tropica) occurs in four disjunct populations in far north Queensland, Australia, at a high density only in its range core (RC). A recent study suggested that B. tropica populations are sparse at the northern and southern range edges (SRE) due to more severe droughts and variable climatic conditions causing fluctuations in the availability of their principal food resource, truffle-like fungi. Truffle availability in the Australian tropics is affected by climate, specifically seasonality of precipitation. We aimed to determine whether the differences in weather patterns between the RC and SRE could be translated to actual differences in truffle availability. Truffle density was consistently lower on the SRE although biomass was slightly higher there due to dominance by drought-tolerant truffle taxa that produce few but large truffles. Lower densities of truffles on the SRE could explain why B. tropica is also less abundant there and why they may be less resilient to competition from the more generalist rufous bettong (Aepyprymnus rufescens). Increasing temperatures and, more importantly, harsher droughts predicted for this region as a result of climate change, may have further detrimental impacts on truffle availability and thus population densities of B. tropica and other mycophagous species.