Potorous gilbertii

Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

Conservation Actions

Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
ANIMALIA	CHORDATA	MAMMALIA	DIPROTODONTIA	POTOROIDAE

Scientific Name:

Potorous gilbertii

Species Authority:

(Gould, 1841)

Common Name/s:

English

–

Gilbert's Potoroo

Synonym/s:

Potorous tridactylus ssp. gilbertii (Gould, 1841)

Assessment Information [top]

Red List Category & Criteria:

Critically Endangered D ver 3.1

Year Assessed:

2008

Assessor/s

Friend, T. & Burbidge, A.

Evaluator/s:

Lamoreux, J. & Hilton-Taylor, C. (Global Mammal Assessment Team)

Justification:
Listed as Critically Endangered because there are currently less than 50 mature individuals. The population of the species appears to be stable, but it is known only from a tiny area, which it appears to fully occupy.

History:

1996

–

Critically Endangered

Geographic Range [top]

Range Description:	Gilbert's Potoroo is endemic to south-western, Western Australia, and was long thought to be extinct until its rediscovery in 1994. It was taken by three collectors between 1840 and 1879 in the vicinity of King George's Sound (Albany), but exact locations are not known. Skeletal material is common in cave deposits between Cape Leeuwin and Cape Naturaliste. Sub-fossil skeletal specimens have been located in coastal sand dunes between these localities. It is currently restricted to Mt. Gardner promontory in Two Peoples Bay Nature Reserve (Friend 2008).
Countries:	Native: Australia
Range Map:	(click map to view full version)

Population [top]

Population:	The population of Gilbert's Potoroo is thought to be 30-40 individuals (Friend 2008). There has been little change in successful trapping, and this probably indicates a stable population (Courtenay and Friend 2004; Friend 2008). All suitable habitat in this species' tiny range appears to be occupied (Friend 2008).
Population Trend:	Stable

Habitat and Ecology [top]

Habitat and Ecology:	This species is found in Melaleuca striata heath with a dense layer of sedges underneath (Courtenay and Friend 2004; Friend 2008). It apparently avoids areas where dieback disease caused by the root pathogen Phytophthora cinnamomi has modified the structure and floristic assemblage of heathlands (Courtenay and Friend 2004). Its diet is highly unusual for a mammal species, and consists almost entirely of fungi (>90%) (Courtenay and Friend 2004). There is little evidence of seasonality in reproduction of this species. Females begin having young at nine months of age. A single young is produced and stays in the pouch for three to four months (Friend 2008). The maximum longevity of both sexes exceeds 10 years (Friend 2008).
Systems:	Terrestrial

Habitat and Ecology:

This species is found in Melaleuca striata heath with a dense layer of sedges underneath (Courtenay and Friend 2004; Friend 2008). It apparently avoids areas where dieback disease caused by the root pathogen Phytophthora cinnamomi has modified the structure and floristic assemblage of heathlands (Courtenay and Friend 2004).

Its diet is highly unusual for a mammal species, and consists almost entirely of fungi (>90%) (Courtenay and Friend 2004). There is little evidence of seasonality in reproduction of this species. Females begin having young at nine months of age. A single young is produced and stays in the pouch for three to four months (Friend 2008). The maximum longevity of both sexes exceeds 10 years (Friend 2008).

Systems:

Terrestrial

Threats [top]

Major Threat(s):	Fire is the critical threat (present and future) to this species as the Mt. Gardner population is in an area of long unburnt and extremely fire prone vegetation, and a single fire event could potentially wipe out the species (except for the few individuals in captivity and on Bald Island) (J. Courtenay pers. comm.). This species is in the prey size range of both feral cats and foxes, and both are known to exist in the Two Peoples Bay area, thus this species is likely threatened by these predators (Courtenay and Friend 2004). Maxwell et al. (1996) states that the reasons for the decline of the species are unknown. Predation by foxes has probably been significant. Changed fire regimes may have altered habitat and/or exacerbated fox and cat predation by destroying dense cover. Gilbert's notes record it as "the constant companion" of Quokkas, Setonix brachyurus (Maxwell et al. 1996). Unlike Gilbert's Potoroo, the Quokka, although declining, persists over much of its pre-settlement range. The difference has not been explained. Maxwell et al. (1996) and Courtenay and Friend (2004), suggest that dieback disease caused by Phytophthora cinnamomi threatens persisting populations by eliminating plant symbionts of hypogeal, mycorrhizal fungi which are the principal food of Gilbert's Potoroos. Altering vegetation structure and eliminating plants that provide food are direct threats to this species.

Major Threat(s):

Fire is the critical threat (present and future) to this species as the Mt. Gardner population is in an area of long unburnt and extremely fire prone vegetation, and a single fire event could potentially wipe out the species (except for the few individuals in captivity and on Bald Island) (J. Courtenay pers. comm.). This species is in the prey size range of both feral cats and foxes, and both are known to exist in the Two Peoples Bay area, thus this species is likely threatened by these predators (Courtenay and Friend 2004).

Maxwell et al. (1996) states that the reasons for the decline of the species are unknown. Predation by foxes has probably been significant. Changed fire regimes may have altered habitat and/or exacerbated fox and cat predation by destroying dense cover. Gilbert's notes record it as "the constant companion" of Quokkas, Setonix brachyurus (Maxwell et al. 1996). Unlike Gilbert's Potoroo, the Quokka, although declining, persists over much of its pre-settlement range. The difference has not been explained. Maxwell et al. (1996) and Courtenay and Friend (2004), suggest that dieback disease caused by Phytophthora cinnamomi threatens persisting populations by eliminating plant symbionts of hypogeal, mycorrhizal fungi which are the principal food of Gilbert's Potoroos. Altering vegetation structure and eliminating plants that provide food are direct threats to this species.

Conservation Actions [top]

Conservation Actions:	The entire known population of this species exists within Two Peoples Bay Nature Reserve (Friend 2008). The most recent recovery plan, Courtenay and Friend (2004), lists the following needed actions for recovery of this species: monitor known populations, undertake protective actions (including fire exclusion, feral animal control, and dieback hygiene), search for additional populations especially outside Two Peoples Bay Nature Reserve, undertake assisted reproduction techniques to enhance reproductive potential, and create new population through translocation. Also, controlling the rate of Phytophthora infection in the habitat of this species is important to the conservation of this species, as well as preserving corridors that link its current habitat with other suitable habitat (i.e., the strip of bushland linking Two Peoples Bay Nature Reserve with the Boulder Hill area) by protecting it from fire and land clearing for grazing and agriculture. A new introduction of a few individuals to Bald Island is underway by the Department of Environment and Conservation (Western Australia). Cat predation research in Two Peoples Bay Nature Reserve is commencing. Extensive research is ongoing on biology and ecology. Surveys have not found any new populations.

Conservation Actions:

The entire known population of this species exists within Two Peoples Bay Nature Reserve (Friend 2008).

The most recent recovery plan, Courtenay and Friend (2004), lists the following needed actions for recovery of this species: monitor known populations, undertake protective actions (including fire exclusion, feral animal control, and dieback hygiene), search for additional populations especially outside Two Peoples Bay Nature Reserve, undertake assisted reproduction techniques to enhance reproductive potential, and create new population through translocation. Also, controlling the rate of Phytophthora infection in the habitat of this species is important to the conservation of this species, as well as preserving corridors that link its current habitat with other suitable habitat (i.e., the strip of bushland linking Two Peoples Bay Nature Reserve with the Boulder Hill area) by protecting it from fire and land clearing for grazing and agriculture.

A new introduction of a few individuals to Bald Island is underway by the Department of Environment and Conservation (Western Australia). Cat predation research in Two Peoples Bay Nature Reserve is commencing. Extensive research is ongoing on biology and ecology. Surveys have not found any new populations.

Citation:	Friend, T. & Burbidge, A. 2008. Potorous gilbertii. In: IUCN 2009. IUCN Red List of Threatened Species. Version 2009.2. <www.iucnredlist.org>. Downloaded on 21 November 2009.
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