Benefits of being a generalist carnivore when threatened by climate change: the comparative dietary ecology of two sympatric semelparous marsupials, including a new endangered species (Antechinus arktos)

Abstract

The endangered black-tailed dusky antechinus (Antechinus arktos) was described in 2014, so most aspects of its ecology are unknown. We examined diet composition and prey selection of A. arktos and a sympatric congener, the northern form of A. stuartii, at two sites in Springbrook National Park. Overall, taxa from 25 invertebrate orders were identified in the diets from 252 scat samples. Dietary components were similar for each species, but A. arktos consumed a higher frequency and volume of dipteran larvae and Diplopoda, while A. stuartii consumed more Coleoptera, Lepidoptera, Orthoptera and Isopoda. Both species of Antechinus had a higher percentage of ‘empty’ scats (devoid of any identifiable invertebrate material) in 2014 compared with 2015. The former was a drier year overall. Lower rainfall may have reduced abundance and diversity of arthropod prey, causing both species to supplement their diet with soft-bodied prey items such as earthworms, which are rarely detected in scats. Comparison of prey in scats with invertebrate captures from pitfall traps showed both species to be dietary generalists, despite exhibiting distinct preference and avoidance of certain prey categories. The ability of an endangered generalist marsupial to switch prey may be particularly advantageous considering the anticipated effects of climate change on Gondwanan rainforests during the mid-late 21st century.

Vegetation structure and ground cover attributes describe the occurrence of a newly discovered carnivorous marsupial on the Tweed Shield Volcano caldera, the endangered black‐tailed dusky antechinus (Antechinus arktos)

“…The study sites were established within the World Heritage‐listed Tweed Shield Volcano caldera, a relic from late Tertiary times (23 mya). Sites were based on a previous study of historical capture records by Baker et al () and parallel research that assessed the present‐day distribution of A. arktos (Gray, Baker, et al, ; Gray Burwell & Baker, ).…”

“…To analyze differences in vegetation structure, a fourth-root transformation was required to reduce the influence of dominant functional groups (Gray et al, 2016;Smith et al, 2017). A resemblance matrix was produced using a Bray-Curtis similarity statistic (Anderson et al, 2008;Bray & Curtis, 1957).…”

“…Forested environments, such as the Gondwanan rainforest relics of the Tweed Shield Volcano caldera, harbor much of the endemic and endangered faunal species occurring in Australian states (Figgis, ; Scarlett et al, ). Since description of A. arktos in 2014, the species has been listed as endangered under both state and federal legislation, due to its highly fragmented, high‐altitude habitat, limited potential for distribution on the caldera, extremely low apparent abundance, and a range of threats exacerbating these problems (Baker et al, ; Gray, Baker, et al, ; Gray, Burwell, & Baker, ; Gray, Dennis, & Baker, ). However, these factors remain poorly understood and need urgent research to ensure effective conservation management (Baker et al, ; Gray, Baker, et al, ; Gray et al, ; Gray, Dennis, et al, ).…”

“…Since description of A. arktos in 2014, the species has been listed as endangered under both state and federal legislation, due to its highly fragmented, high‐altitude habitat, limited potential for distribution on the caldera, extremely low apparent abundance, and a range of threats exacerbating these problems (Baker et al, ; Gray, Baker, et al, ; Gray, Burwell, & Baker, ; Gray, Dennis, & Baker, ). However, these factors remain poorly understood and need urgent research to ensure effective conservation management (Baker et al, ; Gray, Baker, et al, ; Gray et al, ; Gray, Dennis, et al, ). Foundational studies have been conducted on the species' taxonomy by Baker et al () and reproductive biology, population dynamics, and dietary preference by Gray et al (), Gray, Baker, et al (), and Gray, Dennis, et al ().…”

“…However, these factors remain poorly understood and need urgent research to ensure effective conservation management (Baker et al, ; Gray, Baker, et al, ; Gray et al, ; Gray, Dennis, et al, ). Foundational studies have been conducted on the species' taxonomy by Baker et al () and reproductive biology, population dynamics, and dietary preference by Gray et al (), Gray, Baker, et al (), and Gray, Dennis, et al (). Information on the species' habitat use and preference represents a crucial knowledge gap.…”