Spatial and temporal interactions between endangered spotted-tailed quolls and introduced red foxes in a fragmented landscape

Habitat fragmentation can have detrimental impacts on native predators globally through the loss of habitat and associated impacts from introduced predators. The endangered spotted-tailed quoll (Dasyurus maculatus) is the largest marsupial carnivore on mainland Australia and is sympatric with an introduced predator, the red fox (Vulpes vulpes). Spotted-tailed quolls are considered a forest-dependent species and are often associated with large, intact forested habitats where abundance of prey is high and competition with foxes is low. Spotted-tailed quolls are known to persist in some fragmented habitats in sympatry with foxes; however, the mechanisms facilitating this coexistence are unclear. For 15 months in 2018-19, we used camera traps to investigate whether coexistence between quolls and foxes in a fragmented landscape was facilitated by spatial and/or temporal separation of activity. We found no evidence of spatial separation, with quolls detected on the majority of cameras where foxes were detected. There was considerable temporal overlap between quolls and foxes (Delta(1) = 0.71-0.81) and no evidence that fox presence influenced the temporal activity of quolls (Delta(1) = 0.76-0.80). Furthermore, there was no evidence of within-night spatiotemporal avoidance between quolls and foxes (R-2 < 0.01). Our findings suggest that quolls do not offset their spatial and temporal activity to avoid foxes in this fragmented landscape. The spatial and temporal sympatry between quolls and foxes is possibly facilitated by low fox density at this site, suggested by low fox detections. The lack of separation between quoll and fox activity could also explain why quolls become locally extinct in other fragmented landscapes because quolls may not modify their activity to avoid foxes. Future research should focus on investigating quoll and fox interactions along a gradient of fox densities and assess if higher fox densities influence spatial and temporal coexistence with quolls in fragmented landscapes.

Automated summary

In fragmented landscapes, there is no spatial or temporal separation between the endangered spotted-tailed quolls and introduced red foxes, suggesting that the low fox density at the site may facilitate their coexistence. The lack of separation may explain local extinctions of quolls in other fragmented landscapes where they do not modify their activity to avoid foxes. Future research should investigate interactions between quolls and foxes along a gradient of fox densities to understand how higher fox densities impact coexistence in fragmented landscapes.