Landscape-level field data reveal broad-scale effects of a fatal, transmissible cancer on population ecology of the Tasmanian devil

In order to project and plan for the future of threatened species, conservationists require good quality estimates of basic population parameters, such as population sex ratios and breeding rates. These data can be difficult to obtain in many threatened species where pervasive threats perturb population dynamics. For Tasmanian devils, previous studies at several sites across Tasmania revealed demographic consequences of the fatal and transmissible devil facial tumour disease (DFTD). In the current analysis, we take advantage of broad-scale survey data across the state, since 2003, to examine the differences between DFTD-present and DFTD-absent populations at the landscape level. Consistent with expectations based on previous studies, we found that devils trapped in DFTD-present sites were significantly younger (based on tooth-wear age estimates) than those in DFTD-absent sites. Interestingly, we also found that females in DFTD-present sites were more likely to show evidence of breeding than females in DFTD-absent sites. This difference could not be attributed to differences in age or body condition. Devil populations are declining, so increased female breeding rate is unlikely to be successfully compensating for decreased lifespan as a result of DFTD at the population level. These data can be used to inform stochastic and evolutionary models of population dynamics for devils, and inform the assessment of conservation strategies for the species in the presence of disease.