Northern gastric brooding frog
Common name: Northern gastric brooding frog
Scientific name: Rheobatrachus vitellinus
Family: Myobatrachidae (Australian water frogs)
Conservation status: This species is listed as Endangered in Queensland (Nature Conservation Act 1992) and Extinct nationally (Environment Protection and Biodiversity Conservation Act 1999). It is considered a low priority under the Department of Environment and Heritage Protection Back on Track species prioritisation framework.
The northern gastric brooding frog is a moderately large, squat frog that is brown with darker patches on the body and limbs of its upper side, while the abdomen and under side of the hind limbs are a brilliant yellow. The species has a blunt, rounded snout, with nostrils directed upwards, and very prominent eyes. The fingers and toes have slightly extended tips, with the fingers lacking webbing and the toes fully webbed.
Habitat and distribution
In previous surveys, the northern gastric brooding frog was found exclusively in undisturbed rainforest in Eungella National Park. It is an aquatic species, confined to shallow, rocky, broken water areas in cascades, riffles, and trickles of fast flowing perennial streams in rainforest above 400m. During rain individuals were frequently observed on exposed rocks at night. However, this species has undergone a massive and rapid range contraction, and has not been located in the wild since March 1985.
Life history and behaviour
The northern gastric brooding frog has a reproductive behaviour that is unique in the Animal Kingdom, and which was only shared with one other species – the extinct southern gastric brooding frog. Fertilised eggs, or tadpoles, are swallowed by the female, and the tadpoles complete their development in the female’s stomach. The fully formed metamorphs (i.e. a young frog that has almost completed its metamorphosis from a tadpole into an adult) are later regurgitated from the female's mouth, with birth occurring from January to February. In the only documented case, 22 metamorphs were brooded by one female.
The call is loud and consists of several staccato notes repeated in a series, with males calling from September to December.
The northern gastric brooding frog was discovered in January 1984. The then Queensland National Parks and Wildlife Service immediately began a monitoring program to determine if this species was susceptible to a population decline, such as the one which had led to the disappearance of its relative, the southern gastric brooding frog. The monitoring program found that the northern gastric brooding frog was quite common across the range, with up to six frogs occurring in a 2 x 5m area of a shallow stream. However, by January 1985 no individuals could be located at a site on the edge of the distribution, though it was still present at other sites. Since March 1985, the northern gastric brooding frog has not been recorded from any site despite continued efforts to locate it.
The causes of the population decline remain unknown. Investigations found no obvious evidence that seasonal rarity, over-collecting, drought, floods, habitat destruction, disease, heavy parasite loads or stress due to data collection were responsible for the population declines. Current research is examining the possibility that a fungus may have caused the decline of this species.
The recovery plan for the conservation of stream-dwelling frogs of the Eungella region of mid-eastern Qeensland makes the following recommendations:
- Monitor sites where the species was recorded historically to detect any recovery of the species.
- Investigate disease in preserved specimens and in other species occupying similar habitat.
- Train park staff and community volunteers in identification of this species.
- Implement monitoring by park staff of select locations within the national park estate where the northern gastric brooding frog formerly occurred.