Why is one of Australia’s most threatened species not on the Red List?


Copyright: Abby Berryman/DEC https://www.facebook.com/photo.php?fbid=549120408453313&set=pb.283796521652371.-2207520000.1376998014.&type=3&theater
Photo credit: Abby Berryman/DEC https://www.facebook.com/photo.php?fbid=549120408453313&set=pb.283796521652371.-2207520000.1376998014.&type=3&theater

The IUCN Red List is the principal resource for the conservation status of threatened species, yet one of Australia’s most threatened species isn’t on the List, and here’s why:

The Western Ground Parrot Pezoporus flaviventris is effectively confined to a single known population in Cape Arid National Park on WA’s south coast, while a second potentially still persists in Fitzgerald River National Park.

Ground parrots are also found in eastern Australia and the conventional subspecies are the eastern mainland (Pezoporus wallicus wallicus), Tasmanian (P. w. leachii), and western mainland (P. w. flaviventris). A 2011 study (OA) by Steve Murphy et al. used mitochondrial DNA to conclude that ground parrots can be split into two distinct management units (east and west), and suggested that the western ground parrot should be elevated to species status (P. flaviventris) to aid conservation and management.

However, the WGP does not exist on the IUCN Red List (as a separate species) because bird taxonomy follows that of BirdLife International, who only recognise a single species (P. wallicus):

“… despite the finding that western flaviventris differs from eastern wallicus+leachi by 4.4–5.1% in mitochondrial DNA (Murphy et al. 2010), the morphological differences are barely detectable… Our scoring system does not utilise molecular differences, given the absence of any evidence for a consistent degree of divergence as indicating a particular taxonomic status (subspecies, species, genus, etc.). Therefore flaviventris is not recognised as a separate species by the BirdLife Taxonomic Working Group.

While The WGP is classed as critically endangered under federal (EPBC) and WA state legislation, it is not recognised on the List because of these taxonomic rules. It is only represented by the parent species (P. wallicus), which is classed as Least Concern, the lowest category.

Recognition on the Red List is still possible

Regardless of taxonomy, the following Red List rule suggests that the WGP could be included on the list:

“Geographically separate subpopulations of a species are defined as those populations that are so isolated from others of the same species that it is considered extremely unlikely that there is any genetic interchange. In general, listings of such subpopulations should be restricted to those that have been isolated for a long period of time.”

The Action Plan for Australian Birds assessed the WGP as critically endangered under Red List categories A and C:

  • A– population decline greater than 80% over the last 3 generations (29 years) inferred from monitoring, contractions in EOO and AOO and deteriorating habitat quality
  • C– population less than 250 mature individuals, estimated continuing decline greater than 25% in 1 generation, greater than 90% in 1 subpopulation

With only 110 individuals left in the wild, recognition on the Red List would further the public profile and cause of the WGP. I am currently investigating whether a WGP subpopulation nomination has been made to the IUCN in the past. Watch this space!

UPDATE 21/08/2013

Some relevant examples of other taxa where the parent species is listed as Least Concern, but a subpopulation is Critically Endangered include:

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