Space use and temporal partitioning of sympatric Tasmanian devils and spotted‐tailed quolls

Abstract

Sympatric species can minimise interspecific competition by spatial avoidance or by altering their temporal activity to reduce encounter rates. The Tasmanian devil (Sarcophilus harrisii), the largest carnivorous marsupial, coexists with the smaller spotted-tailed quoll (Dasyurus maculatus) in Tasmania, Australia. Quolls may be susceptible to interspecific competition from devils, because they utilise similar habitats, consume similar prey species and are displaced by devils at food sources. Such competition might cause quolls to spatially or temporally avoid devils. To investigate whether spatial or temporal avoidance occurred, we deployed GPS collars on sympatric devils and quolls and conducted a camera survey at a site in northwest Tasmania where the devil population was not affected by devil facial tumour disease. GPS tracking coincided with the lactation period when devils and quolls had young in dens and continued until weaning occurred. We found little spatial segregation of home range and core area placement between devils and quolls and among devils. Quolls showed more spatial segregation within the sexes than between them. Devils had larger home ranges than quolls. Male devils had larger home ranges than females, but there was no difference in home range size between the sexes of quolls. Females of both species travelled significantly further per night than did males. There was moderate temporal partitioning between the two species: devil activity peaked after dusk and devils remained active until the early morning, while quoll activity showed distinct peaks around dusk and dawn. In conclusion, quolls did not spatially avoid devils but moderate temporal partitioning occurred. It is plausible that quolls are active at different times of the diel cycle to reduce encountering devils, but further studies are needed to resolve the cause of this temporal partitioning.

Activity and social interactions in a wide-ranging specialist scavenger, the Tasmanian devil (Sarcophilus harrisii), revealed by animal-borne video collars

“…this study area [27], which showed that most devils became active at sunset, movement rates gradually reduced after midnight, and most devils were stationary by sunrise. The first hour of footage following the release of a devil from the trap was considered likely to be atypical and was excluded.…”

“…Devils were trapped in custom built pipe traps (diameter 315 mm x length 875 mm, constructed from solid PVC pipe; N. Mooney and D. Ralph, unpublished data) baited with meat. Nearly all of the devils on the study site (n = 142) were already microchipped as part of a long term study on devil movement [16,27]. Only devils that have been trapped several times before were fitted with a camera, to ensure a high probability of recapture for collar retrieval.…”

“…Interactions at dens and carcasses were much less frequent but with a similar low frequency of physical contact and biting. This suggests that the individual devils on the study area, which occupy overlapping home ranges [27] have established dominance relationships, which also are maintained by displays of non-contact behaviours [10]. Little is known about the ecology of wild devil dens but one study found that individuals use between one and ten dens and change dens every few days [19].…”

“…Devils are a solitary carnivore that have overlapping home ranges (2531ha) [27], and interact agonistically around prey carcasses and during mating [9][10][11]. Knowledge of social contact and biting behaviours relevant to disease transmission is crucial for understanding disease spread and epidemic outcome, and for informing disease management options.…”

Assessing the value of restoration plantings for wildlife in a temperate agricultural landscape

“…Wide‐ranging marsupial carnivores, spotted‐tailed quolls and Tasmanian devils, were recorded throughout the Midlands landscape, including in riparian plantings. Quolls and devils travel daily up to 22 and 8 km, respectively, across a wide range of habitats including paddocks and forest (Andersen et al 2020) and disperse up to 100 km, indicating that no amount of habitat fragmentation in Tasmania presents a significant barrier (Lachish et al 2011; Proft 2019).…”