Disease triggers shift in devil demographics
TASMANIAN devils are breeding younger, meaning they are surviving in the wild but also contracting devil facial tumour disease earlier in life, new research has found.
Devil densities at monitoring sites had decreased by about 80 per cent in diseased areas since the emergence of the tumour, said wildlife biologist and lead author Billie Lazenby, of Save the Tasmanian Devil Program.
The monitoring research was conducted by the Save the Tasmanian Devil Program in collaboration with staff from the Department of Primary Industries, Parks, Water and the Environment, San Diego Zoo Global, Toledo Zoo and the University of Tasmania.
The structure of the wild devil populations in disease areas had shifted dramatically over the years, with devils over the age of two being very rare in comparison with the days before devil facial tumour disease, Dr Lazenby said.
“Devils in diseased areas are now breeding younger and having more pouch young, which has allowed them to persist at low levels in the wild,” she said.
“Earlier breeding in young devils means that they are contracting DFTD younger, often as one year olds.”
They were now dealing with very small and poten- tially isolated groups of devils across Tasmania, Dr Lazenby said.
As a result, such large reductions in devil numbers and the change in their age structure meant they would be more susceptible to roadkill death, bushfires and a loss in genetic diversity, Save the Tasmanian Devil Program manager and senior author David Pemberton said.
They would also be adversely affected by variation in food availability due to drought and changes in the ecosystem as it responded to the loss of devils in the wild.
The program was trying to reduce the incidence of devil roadkill in known black spot areas.
It also hopes to lift devil numbers and genetic diversity by releasing devils into the wild, Dr Pemberton said.
Efforts to manage the devils, such as the development of an immunotherapy, were continuing but remained in a research and development phase.