Endangered Species Monday | Potorous gilbertii - Back From The Brink Of Extinction.

Endangered Species Monday | Potorous gilbertii

This Monday’s (ESP) post, I’ve decided to document a little more on Australia’s wildlife. This Monday I have dedicated this post to one of Australia’s most endangered marsupials. Commonly known as the Gilbert’s Potoroo. (Image Credit Parks and Wildlife Australia).

Identified as the worlds ‘rarest marsupial’, the species is scientifically known as the Potorous gilbertii. Listed as (critically endangered) the species was primarily identified back in 1841 by Dr John Gould FRS - 14 September 1804 – 3 February 1881) who was a British ornithologist and bird artist. He published a number of monographs on birds, illustrated by plates that he produced with the assistance of his wife, Elizabeth Gould, and several other artists including Edward Lear, Henry Constantine Richter, Joseph Wolf and William Matthew Hart.

Dr Gould has been considered the father of bird study in Australia and the Gould League in Australia is named after him. His identification of the birds now nicknamed “Darwin’s finches” played a role in the inception of Darwin’s theory of evolution by natural selection. Gould’s work is referenced in Charles Darwin’s book, On the Origin of Species.

Life hasn’t been at all easy for the P. gilbertii. It was only back in 2012 that conservation and environmental scientists (rediscovered) the species of which it was believed the marsupial had gone completely extinct within the wild. Endemic to Australia there is very little known in relation to when threats came about, increased and decreased. However I can state now; as small as populations are known - P. gilbertii’s populations are ‘currently stable within the wild’.

While though populations are stable, there are only thirty to forty actually known to be living within their endemic wild, so there is still a large amount of concern for the worlds most endangered marsupial. Back in early 1980’s the species had been listed as (completely extinct within the wild after studies from the 1800’s turned up nothing). Fortunately though environmental scientists went on the prowl and were not under any circumstances ready to write this species off whatsoever. They were technically looking for an animal that hadn’t been seen since the 1880’s-1990’s. Their work though eventually paid off.

“THEN CAME A BREAK THROUGH IN 1994”

Environmental scientists come 1992-1993 were ready to write the species off, call off all explorations and projects that were aimed at hopefully rediscovering the species. Fortunately though the Australian Parks and Wildlife Service persisted - and come 1994 a spotting was recorded. After so many years believing the Gilbert’s Potoroo had gone extinct, scientists discovered an extremely small population - to the joy of many. Finally there was hope, and today the species remains under full governmental protection.

Native to South-western and Western Australia the remaining populations was taken by three collectors between 1840 and 1879 in the vicinity of King George’s Sound (Albany), but exact locations are unknown. 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.

The entire population (consisting of 30-40 mature individuals) as explained above remains inhabits the Two Peoples Bay Nature Reserve of which they enjoy protection from the local parks wildlife board. While populations are identified as extremely small, mother will give birth to either 1-2 babies every year, normally its 2 babies. Like kangaroos the species has the ability to keep a second embryo in a state of diapause while the first embryo is growing. If the first baby does not go to term, a second baby starts growing right away.

Check out the Gilbert’s Potoroo Action Group by clicking this link

Diapause is considered a rare phenomena - especially in kangaroos, although its been witnessed quite a lot over the past few years by European, British and Australian Zoologists. The last diapause event (that I’m aware of) was witnessed at the Taronga Zoological Gardens in Australia. You can read the story >here.< The gestation period for Gilbert’s potoroo is unknown, but is estimated to be similar to the long-nosed potoroo at 38 days.

Since so few are alive today, much of the reproductive cycle for Gilbert’s potoroo remains unknown. However, the main breeding period is thought to be November–December with similar breeding patterns to those of the long-nosed potoroo. Scientists have tried to breed them in captivity, but recent attempts have been unsuccessful, citing diet, incompatibility, and age as possible factors that influenced the lack of reproduction. Reproduction in the wild is thought to be progressing successfully as many females found in the wild are with young.

Image: Gilbert’s Potoroo. Photographer Mr Dick Walker. 

In 2001, the Gilbert’s Potoroo Action Group was formed to help in the education and public awareness of the potoroo. The group also helps with raising funds for the research and captive-breeding programs for Gilbert’s potoroo. In efforts to protect the remaining population, three Gilbert’s potoroos (one male and two females) were moved to Bald Island in August 2005, where they are free from predation. Since that time, an additional four potoroos have been sent to establish a breeding colony.

THREATS

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). 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.

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

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.

For now and based on various accounts, research and up to data documentaries. The species is still in danger. As explained above a single large and sporadic fire within the species habitat - could kill off the entire identified populations, which would be a catastrophe. While there is minimal threat from predators such as foxes and feral cats - this could change. So the need for persistent monitoring is a must. Finally we have disease, with populations being so small at around 30-40, any single disease could like fires wipe the entire species out within a single week.

Within the article above I’ve included various links for your immediate attention and information, as well as a link to the main working group that is helping (and doing all they can) to preserve the species. Furthermore I’ve included a donation link for you to donate to the Gilbert’s Potoroo Action Group. While I’m not entirely sure whether you can volunteer, there is a link on the main website below (highlighted: Volunteer Today). Just click the link, follow the instructions and, I’m confident someone will get back to you as soon as possible.

Volunteer Today

Thank you for reading, please don’t forget after reading to share this article, and hit the like button too. 

Dr Jose Carlos Depre Depre PhD. MEnvSc. BSc(Hons) Botany, PhD(NeuroSci) D.V.M.

Environmental & Human Science