Susceptibility to climate change via effects on food resources: the feeding ecology of the endangered mountain pygmy-possum (Burramys parvus)

Abstract

Context Climate change is causing changes to seasonal food resources, with critical health and survival impacts for many species. The endangered Burramys parvus (mountain pygmy-possum) predominantly consumes Agrotis infusa (Bogong moth), a long-distance seasonal migrant. Aims We aimed to examine direct and indirect climate-related influences on B. parvus food resources so as to assess the susceptibility of the species to climate change. Methods We analysed a long-term (17-year) data record of B. parvus faecal samples from sites across a climate gradient, in relation to plant-growth indices derived from climate data. We also modelled the population dynamics of A. infusa against climate variables and in relation to the probability of consumption by B. parvus. Key Results The diet of B. parvus was highly variable among sites and years and there were strong seasonal patterns for predominant food resources (A. infusa, other local arthropods, Podocarpus sp. and other local seeds). Seasonal patterns generally diminished with an increasing elevation, which may be due to resource availability or complex interactions with food preferences. Growth conditions across spatially far removed A. infusa breeding grounds influenced their abundance recorded in the Alps in spring, which was reflected in B. parvus diet. Conclusions Strong seasonal and climatic influences on dominant food resources suggest that B. parvus may be susceptible to climate change. Selective foraging for the lipid-rich A. infusa and Podocarpus sp. seed suggests that there may be important health and survival benefits for B. parvus. Implications Given the dependence on cooler, higher-elevation aestivation sites, A. infusa may have reduced survival in a warmer world. Climate change across the vast migratory route of A. infusa is likely to further affect survival and availability for consumption by B. parvus. Predicted increases in fire frequency and severity may reduce availability of the fire-sensitive Podocarpus sp. The health and survival of B. parvus may be compromised as a result of reduced availability of A. infusa and Podocarpus seed and a greater dependence on angiosperm plants (seeds and nectar) and local arthropods because of the consequent change in dietary lipid composition. Integrated predictive modelling of A. infusa and B. parvus population dynamics under future climate-change scenarios is recommended.