In late 2005, Perth Zoo was awarded a grant from the Western Australian Office of Science, Technology and Innovation to establish a frog breeding research program.
As part of the program, Perth Zoo investigated the reproductive biology and husbandry requirements of some of Western Australia’s frog species. These included three Geocrinia species (the more common Roseate Frog (Geocrinia rosea), and the threatened Orange-bellied Frog (Geocrinia vitellina) and White-bellied Frog (Geocrinia alba)), the Sunset Frog (Spicospina flammocaerulea) and two species from the Kimberley region (Notaden weigli and Litoria cavernicola). Most of these species had never been kept or successfully bred in captivity before. Therefore, determining the best living conditions and how to get the animals to breed were all-important processes in the research.
Over four years, Perth Zoo has had success in breeding and rearing these species in captivity. The Cave-dwelling Frog (Litoria cavernicola) was the first one to be successfully bred at the Zoo and this was followed by the Roseate Frog and the Sunset Frog.
In 2008-09 Perth Zoo also successfully reared the White-bellied Frog using techniques refined with the common analogue species, the Roseate Frog. These were reared from two egg nests collected from the wild. The knowledge gained from breeding, rearing and housing the common Roseate Frog is extremely important as it can be used as an analogue species for the other two, more threatened, Geocrinia species (White-bellied and Orange-bellied Frogs). Analogue species used are more common and usually closely related so share similarities with the other, more threatened, species.
Now that the Roseate Frog has offered up its secrets, Perth Zoo is working hard to see how they relate to the White-bellied Frog and the Orange-bellied Frog.
Breed, Rear and Release Program for White-bellied Frogs
White-bellied Frog.
In November and December 2009, Perth Zoo and Department of Environment and Conservation staff collected White-bellied Frog egg nests from the wild for rearing at the Zoo to boost their chances of survival. After 10 months of growth and development at Perth Zoo, 60 frogs have been returned home.
On 13 September, the frogs were released into a creek near Witchcliffe, in Western Australia’s south-west, in an effort to re-establish the critically-endangered amphibians in an area where they had become locally extinct.
The frogs were at various life stages from metamorphs to adults. Egg nests are heavily predated on in the wild so removing them and rearing them at Perth Zoo in a safe environment has helped increase their chances of reaching adulthood. Eight White-bellied Frog egg nests were collected from the wild last year. Ninety-nine metamorphs emerged of which 74 have survived with 60 released.
Each released frog was marked under the skin of either its leg or belly with a product called Visible Implant Elastomer, which looks a bit like a small, colourful tattoo. These will be used in future monitoring studies to determine whether a frog was one of the released ones (it will have a colourful tattoo) or one bred from our released frogs (it won’t have a mark under its skin). It is hoped researchers will find some egg nests or new unmarked frogs.
Looking for frogs in the wild.
The White-bellied Frog is confined to a very limited and isolated ecological niche and as such is susceptible to changes in its environment. Unfortunately, many changes have taken place in its range including habitat clearing, fire and changes in climate and water quality. Illegal activities such as the growing of drug crops and firewood chopping in the national parks where the frogs are found are also affecting their numbers. The Department of Environment and Conservation has programs in place to address threatening processes that may affect the release site.
The White-bellied Frog rear-for-release program has been possible thanks to the State’s Natural Resource Management funding, Perth Zoo’s Wildlife Conservation Action and the Zoo and Aquarium Association.
More information about this program can be read in the Minister for the Environment’s press release.
Find out about frog hormone testing and what research was undertaken to ensure males and females were released into areas close to one another to improve breeding success in the wild.
About the White-bellied Frog
White-bellied Frog Egg Nest with metamorphs.
The White-bellied Frog (Geocrinia alba) is listed as Critically Endangered and has possibly as few as 200 individuals remaining in the wild. The species continues to decline annually despite conservation action, however, the cause of this decline is unknown. Determining the cause of the decline and developing a method to address the decline are of high importance.
Unlike commonly known frog species, the species in the Geocrinia group are known as direct developer species. This means that their tadpoles do not free-float in water but instead develop inside a jelly-like egg-mass, placed under or on leaf litter. Inside the egg mass, the tadpoles go through all stages of development before jumping out as a fully formed, though young and not full-sized, frog.
