Models predict that culling is not a feasible strategy to prevent extinction of Tasmanian devils from facial tumour disease
Beeton, N and McCallum, H, Models predict that culling is not a feasible strategy to prevent extinction of Tasmanian devils from facial tumour disease, Journal of Applied Ecology, 48, (6) pp. 1315-1323. ISSN 0021-8901 (2011) [Refereed Article]
1. Culling, either of all animals or infected animals only, is often suggested as a way of managing
infectious diseases in wildlife populations. However, replicated experiments to investigate culling
strategies are often impractical because of costs and ethical issues. Modelling therefore has an
important role. Here, we describe a suite of models to investigate the culling of infected animals to
control an infectious cancer in the Tasmanian devil Sarcophilus harrisii.
2. The Tasmanian devil is threatened by an infectious cancer, Tasmanian devil facial tumour
disease. We developed deterministic susceptible, exposed and infectious (SEI) models with diﬀering
ways of incorporating the time delays inherent in the system. We used these to investigate the
eﬀectiveness for disease suppression of various strategies for the removal of infected animals.
3. The predictions of our models were consistent with empirical time series on host population
dynamics and disease prevalence. This implies that they are capturing the essential dynamics of the
system to a plausible extent.
4. A previous empirical study has shown that removals every 3 months did not appear to be
suﬃcient to suppress disease in a semi-isolated infected population. Our models are in accordance
with this observed result. The models further predict that while more frequent removals are more
likely to be eﬀective, the removal rate necessary to successfully eliminate disease may be too high to
5. Synthesis and applications. Our results, in association with a previous experimental study, show
that culling is unlikely to be a feasible strategy for managing Tasmanian devil facial tumour disease.
Similar conclusions have been reached in studies of other wildlife diseases. We conclude that culling
is rarely appropriate for controlling wildlife diseases and should only be attempted if models predict
that it will be eﬀective.