Conservation Biology

Volume 28, Number 1, February 2014Featured

Paper…

© Tracey Hollings

a photo essay…

Trophic Cascades Following the Disease-Induced Decline of an Apex

Predator, the Tasmanian Devil

Contributed Paper by: Tracey Hollings

Menna JonesNick Mooney

Hamish McCallum

Conservation Biology February 2014

Mark Burgman, Editor-in-Chief

www.conbio.org

Published by Wiley

©Rodrigo Hamede

The Tasmanian Devil is threatened with extinction from a transmissible cancer, devil facial tumor disease.

The Tasmanian Devil is threatened with extinction from a transmissible cancer, devil facial tumor disease.

Devil facial tumor disease (DFTD) has led to apparent

population declines of Tasmanian Devils in excess of 95% in some areas and has spread to more than 80% of

their range.

(Hollings, 2013)

Trophic cascades following the disease-induced decline of an apex predator, the Tasmanian Devil

Conservation Biology - Vol 28, Issue 1, February 2014

©Georgina Anderson

The Tasmanian devil is the apex mammalian predator in the Tasmanian ecosystem. As apex predators disappear worldwide, there is escalating evidence of their importance in maintaining the integrity

and diversity of the ecosystems they inhabit... Wild Tasmanian devils at home in a den.

The Tasmanian devil is the apex mammalian predator in the Tasmanian ecosystem. As apex predators disappear worldwide, there is escalating evidence of their importance in maintaining the integrity

and diversity of the ecosystems they inhabit... Wild Tasmanian devils at home in a den.

©Ryan Burrows

DFTD was first detected in the north-east of Tasmania in 1996. Prior to its arrival, devils were widespread and have

been recorded in all Tasmanian vegetation types.

A sub-adult female polar bear on a frozen lake along the shore of Hudson Bay. Small bears like this are usually wary of adult males which can be predatory.

Rapid Ecosystem Change and Polar Bear ConservationConservation Letters Map of Tasmania

showing individual spotlight survey transects within

each of 4 regions representing

different year ranges of arrival of

DFTD (late, mid, disease-free,

early). Years are range of arrival of

DFTD in each region.

Hollings, 2013

©Hugh Maguire

©Ryan Burrows

©Ryan Burrows

Unlike mainland Australia, Tasmania retains a nearly intact mammalian fauna community.

Unlike mainland Australia, Tasmania retains a nearly intact mammalian fauna community.

Our results suggest that the decline of the Tasmanian devil, the apex

mammalian predator in the Tasmanian ecosystem, has had a

substantial effect on terrestrial mammal fauna, a result consistent

with evidence from apex predator loss in other ecosystems

(Hollings, 2013)

Conservation Biology - Vol 28, Issue 1, February 2014

Trophic cascades following the disease-induced decline of an apex predator, the Tasmanian Devil

Maintaining populations of the devil in the Tasmanian ecosystem, at

densities sufficient to exert top–down control, may protect populations of

smaller mesopredators…

Conservation Biology - Vol 28, Issue 1, February 2014

Trophic cascades following the disease-induced decline of an apex predator, the Tasmanian Devil

©Tracey Hollings

There is strong compelling evidence to support the assertion that devils can exert top-down control on feral

cat populations.

There is strong compelling evidence to support the assertion that devils can exert top-down control on feral

cat populations.

Feral cats like this one increase in areas where DFTD has been present the longest & feral cat occurrence is significantly and

negatively associated with devils.

©Tracey Hollings

As devil populations declined and cats

increased, the smaller native mesopredator,

the eastern quoll (pictured), declined, and

there was no sign of population recovery,

which lead to concerns for its conservation.

©Menna Jones

The best-fitting generalized linear model (GLM) for the mean number of animals per transect for devils & eastern quolls. The best model, the linear model for feral cats, was not significantly different from models containing a DFTD arrival variable, so the second-best model was used to illustrate devil facial tumor disease arrival effects (vertical lines,

period of disease arrival; shaded areas, 95% CIs for GLMs; points, actual values).

Our results are consistent with assertions that DFTD causes rapid and severe population decline in devils that results in substantially reduced apex predator

populations within a few years.  There was no indication of population recovery, and with no

effective management options at present that could aid recovery of wild populations, the trophic

cascades in the Tasmanian ecosystem resulting from loss of devils are likely to continue.

Conservation Biology - Vol 28, Issue 1, February 2014

Trophic cascades following the disease-induced decline of an apex predator, the Tasmanian Devil

SCB Members log in to your member home page at

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Trophic Cascades Following the Disease-induced Decline

of an Apex Predator, the Tasmanian Devil

Note: The February issue is freely available at:

http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1523-1739

©Tracey Hollings