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GILBERT'S POTOROO - AUSTRALIA'S MOST ENDANGERED MAMMAL

Gilbert's Potoroo - Conservation Action


Conservation Status

Gilbert's Potoroo is known only from a single, very small population on Mount Gardner, in Two Peoples Bay Nature Reserve, near Albany, Western Australia. The wild population is estimated to number between 30 and 40 individuals and occurs in an area of about 1000 ha.

The current conservation status of Gilbert's Potoroo is listed as:

  • Fauna that is likely to become extinct or is rare (Western Australian Wildlife Conservation Act 1950)
  • Critically Endangered by the WA Threatened Species Scientific Committee
  • Endangered under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act)
    [but currently nominated for Critically Endangered status]
  • Critically Endangered in The 1996 Action Plan for Australian Marsupials and Monotremes (Maxwell, Burbidge & Morris, 1996)
  • Critically Endangered in the 2003 IUCN Red List of Threatened Species according to criteria:
    • C2b (Number of mature individuals is less than 250, declining and all individuals are in a single subpopulation)
    • D (Number of mature individuals is less than 50)

Gilbert's Potoroo Recovery Team

In 1995, soon after the rediscovery of Gilbert's Potoroo, a Recovery Team was formed to coordinate actions to improve the conservation status of Gilbert's Potoroo. Membership of the team now includes representatives from WA Department of Conservation and Land Management (CALM), Perth Zoo, universities, conservation organisations and community groups. As at June 2003, the Recovery Team comprised ten members including a representative from Gilbert's Potoroo Action Group.

The keys to conserving Gilbert's Potoroo are to ensure that the single known wild population persists, and to increase the number of locations at which the species occurs. This will require:

  • monitoring of known populations
  • undertaking protective actions including fire exclusion, feral animal control and dieback hygiene
  • searching for additional populations, especially outside Two Peoples Bay
  • undertaking assisted reproduction techniques to enhance the reproductive potential of the species, and
  • creating new populations through translocation.

These efforts were guided initially through the Interim Wildlife Management Guidelines for Gilbert's Potoroo and later through the Gilbert's Potoroo Recovery Plan. The Recovery Team's role is to determine the best strategy for recovery and to oversee the writing and implementation of these plans. Return to Top of Page/ Menu

Gilbert's Potoroo Recovery Plan

Gilbert's Potoroo Recovery Plan, written by Jackie Courtenay and Tony Friend, is a CALM Wildlife Management Program developed to delineate, justify and schedule management actions necessary to support the recovery of Gilbert's Potoroo. The Recovery Plan covers these actions in detail but, to summarise the salient points, the objective, success criteria and recovery actions are reproduced below:

 

Recovery Objective:
The objective of the Gilbert's Potoroo Recovery Plan is to increase both the numbers of individual Gilbert's Potoroos known to be alive in the wild and the number of locations in which they occur.

Recovery Criteria:
The Recovery Plan will be deemed successful if:

  • The number of individuals known to be alive in the wild remains stable or increases, and
  • The species is found at, or successfully reintroduced to, at least one other location.

The Recovery Plan will be deemed to have failed if:

  • The estimated total number of mature individuals declines by more than 20% within five years.

Recovery Actions:

  1. Protect the existing wild population and habitat
  2. Increase understanding of ecology and population biology of Gilbert's Potoroo to underpin management strategies
  3. Search for new populations of Gilbert's Potoroo outside Two Peoples Bay
  4. Establish and maintain a captive breeding colony of Gilbert's Potoroo
  5. Develop techniques to enhance the reproductive potential of Gilbert's Potoroo
  6. Enhance the breeding capacity of Gilbert's Potoroo
  7. Extend the range of Gilbert's Potoroo through translocation of animals to suitable habitat outside Two Peoples Bay
  8. Secure ongoing funding for the implementation of the Recovery Actions

The Recovery Plan breaks down these eight top-level actions into a detailed and prioritised recovery program. Gilbert's Potoroo Action Group actively works with CALM and the Gilbert's Potoroo Recovery Team to implement this recovery program. Return to Top of Page/ Menu

Threatening Processes

The most significant threats to the survival of Gilbert's Potoroo have been identified as:

Fire
The only known wild population of Gilbert's Potoroo exists in dense, long unburnt vegetation that is potentially highly vulnerable to wildfire. Fire exclusion is thus an extremely high priority in the protection of the wild population. The captive colony was established at least partly to provide insurance against the loss of the single known population through a catastrophic fire event.

Feral predators
Gilbert's Potoroo is within the Critical Weight Range (35g to 5kg) of mammals thought to be most susceptible to decline. It is in the prey size range of both Foxes and Cats, both of which are known to occur in the Two Peoples Bay area. Dietary analysis of the gut contents and faeces of a feral Cat trapped at Mt Gardner in 2001 revealed that it had consumed both Quenda (Bandicoot) and Noisy Scrub-bird. Control of feral Cats would thus also be beneficial to other threatened mammals and birds in the area.

Dieback disease Phytophthora cinnamomi
Potoroos are believed to be present only in areas of the Reserve that are free of Dieback infection which can cause considerable changes to the floristic structure of the habitat. Gilbert's Potoroo feeds primarily on hypogeal fungi, many of which are mycorrhizal. Plant dieback disease is considered to be a major threat to the continued survival of the potoroo by altering vegetation structure or eliminating species that are hosts to the mycorrhizal fungi on which they feed.

Clearing of vegetation adjacent to Two Peoples Bay
The population of Gilbert's Potoroo on the Mount Gardner headland has the potential to expand through the dispersal of young through adjacent bushland corridors into suitable habitat nearby (especially near Mount Manypeaks). Some of this linking bushland occurs on private land. Unless these corridors are protected from clearing, the chance of successful dispersal to new areas will be very small. Return to Top of Page/ Menu

Gilbert's Potoroo Captive Colony

After the rediscovery of Gilbert's Potoroo in 1994, one of the first management decisions taken by the Recovery Team was to keep some animals in captivity. There were two reasons:

  1. As insurance; there was no evidence that the species existed anywhere but on Mt Gardner which is covered in highly flammable heath. A large wildfire could have been catastrophic.
  2. Recovery would require the establishment of populations at other sites to increase the number of individuals and to spread the risk of catastrophes affecting most or all extant individuals.

From December 1994 through to April 1996 a breeding colony of nine animals was founded, comprising:

  • Four adult females (together with the young-at-heel and pouch-young listed below)
  • One adult male
  • One juvenile male
  • One male young-at-heel
  • One male pouch-young, subsequently raised to independence
  • One female pouch-young, subsequently raised to independence

Eight cages, designed specifically for the captive colony, were built in a low-fuel buffer zone in Two Peoples Bay Nature Reserve. The facility, which is run by CALM, was enlarged in 2000 by the construction of six more cages.

While the colony grew from the initial nine founders to a maximum of 14 animals in 1998, reproductive rates have been much lower than anticipated and, as the original animals grow old, deaths in the colony have now reduced numbers to only five animals (February 2004). Although females are capable of producing at least two young each year, some captive females have produced no offspring and only eight captive-bred young have been produced in eight years. Reasons for the depressed reproduction are unclear but various possibilities including diet, genetics (inbreeding depression), proximity and social behaviour are being investigated. As the captive colony has not achieved the original goals using only natural breeding, the use of assisted reproduction is being investigated:

  • Research to develop techniques for artificial insemination in potoroos is proposed. Techniques will be developed and optimised in Long-nosed Potoroos at Perth Zoo before trials with Gilbert's Potoroos at the Two Peoples Bay breeding facility. If successfully applied to Gilbert's Potoroos, this technique will not only enable more young to be produced, but will also overcome any behavioural incompatibility and thus allow better genetic management.
  • The feasibility of cross-fostering young from the wild, using Long-nosed Potoroos as foster mothers, is being investigated to increase the overall reproductive rate and possibly to enhance the genetic variability in the captive colonies. Cross-fostering could also be used to increase the rate of output of young produced in captivity either by natural means or by artificial insemination.

The establishment of a self-sustaining captive population which can produce sufficient animals to reintroduce into habitat outside the Mt Gardner area is considered a vital strategy in the recovery of Gilbert's Potoroo. Return to Top of Page/ Menu

How You Can Help

What can you do to help with conservation?

  • Learn more about endangered species and spread the word to family, friends and colleagues. Our More Information page is a good starting point for further research and includes links to other relevant sites and a list of further reading.
  • Join a conservation organisation such as:
    • Our Gilbert's Potoroo Action Group
    • Australian Conservation Foundation
    • World Wide Fund for Nature
    These organisations can also often offer volunteers opportunities for hands-on involvement in conservation work.
  • Organise a fund raising activity for Gilbert's Potoroo. Donations can be given to:
    • Gilbert's Potoroo Action Group
    • CALM
    • Perth Zoo

If you think you may have seen a Gilbert's Potoroo, or found animal remains which you think could be a Gilbert's Potoroo, please check our sightings page which gives guidance on distinguishing Potoroos from similar animals and complete the online sighting report; alternatively, you can note down the sighting details as listed on the page and contact us at: