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	Conservation Status (definitions)
IUCN (Red List) Status	Extinct (EX) See threat category on the IUCN web site.
CITES	No CITES Listing
Other International Status	None
National Status	None
Regional Status	None

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Australia

View distribution map using BerkeleyMapper.

Population and Distribution
Rheobatrachus silus was restricted to elevations between 400-800 m in the Blackall and Conondale Ranges in S.E. Queensland (Hines et al. 1999). The geographic distribution of the species was less than 1000 km2 (map in Hines et al. 1999). Rheobatrachus silus inhabited streams in the catchments of the Mary, Stanley and Mooloolah Rivers (Ingram 1983). Rheobatrachus silus was thought to have been first found in 1972 (Liem 1973) but Ingram (1991) reported a specimen collected in 1914 from the Blackall Range. The species declined rapidly and disappeared at about the same time as a sympatric species Taudactylus diurnus (Czechura and Ingram 1990). Czechura and Ingram (1990) and Ingram (1990) state that the last frog was seen in the wild in 1979 on the Conondale Range. Richards et al. (1993), however, reported the existence of a specimen taken from the Blackall Range in 1981. Despite intensive searching, the species has not been located since (Ingram and McDonald 1993; Hines et al. 1999). In the laboratory, the last known individual died in 1983 (Tyler and Davies 1985). Ingram (1983) studied a population of the species in the headwaters of Booloumba Creek, Conondale Range, and estimated that approximately 78 were present in 1976. No other estimates of population size are available for the species.

Rheobatrachus silus was formerly known from Kondalilla and Conondale NP, Sunday Ck, SF311 and Kenilworth SF and from private land outside these areas (Hines et al. 1999; H. Hines pers. comm.).

Habitat
Rheobatrachus silus lives in rainforest, wet sclerophyll forest and riverine gallery open forest at 350 m asl and is closely associated with watercourses and adjacent rock pools and soaks (Czechura 1991; Meyer et al. 2001). These streams are mostly perennial, but in extremely dry years they may cease to flow (Ingram 1983). The vegetation along the stream banks is usually closed forest or tall closed forest with emergent eucalypts, although there are some sites in open forest with grassy ground cover (Ingram 1983). In spring and summer individuals are usually found in or at the edge of rock pools, either amongst leaf litter, under and between stones or in crevices around the edge (Ingram 1983). The species is also found under rock in shallow water in backwaters and also the main flow of permanent watercourses (Ingram 1983; Czechura 1991). Searches of popular sites in winter only recovered two frogs and it is assumed that the species hibernates in deep crevices in rocks or spaces between rocks underwater during the colder months (Ingram 1983). Adult males tend to prefer deeper pools, whereas females and juveniles may move to newly created pools after rain as long as these pools contained stones and/or leaf litter (Ingram 1983). The prerequisite for the use of pools by R. silus seems to be that the pool must be deep enough for the frog to be able to sit with its head out of the water and be able to safely submerge (Ingram 1983). Individuals will only sit fully exposed on the rocks during light rain (Ingram 1983). Rheobatrachus silus has never been recorded from cleared riparian habitat.

Life History, Abundance, Activity, and Special Behaviors
Reproduction
Breeding activity occurs between October and December (Ingram 1983). Males call from rock crevices above pools (Ingram 1983). Female R. silus brood young within the stomach and give birth through the mouth (Tyler and Carter 1982). Fertilised eggs or early stage larvae are presumably swallowed by the female and complete their development in the stomach (Tyler and Carter 1982). The number of eggs in gravid females (approximately 40) exceeds the number of juveniles found to occur in the stomach (21-26) (Tyler 1989). It is not known whether the excess eggs are digested by the female or whether they are simply not swallowed (Tyler 1989). The production of hydrochloric acid in the stomach of the female ceases during brooding (Tyler et al. 1983).

Tadpoles develop in a manner similar to the aquatic tadpoles of other species, but feed off egg yolk, are lacking labial teeth, and form the intestines at a later stage of development (Tyler 1989).

After 6-7 weeks the females give birth to up to 25 young (Tyler and Davies 1983a). Young emerge from the female’s mouth as fully formed frogs and after 4 days the digestive tract returns to normal and the female recommences feeding (Tyler and Davies 1983b). Ingram (1983) reported minimum brooding periods from two individuals of 36 and 43 days and suggested that the duration was such that females were unlikely to breed twice in one season.

Feeding
Rheobatrachus silus has been observed to forage and take insects from both land and water (Ingram 1983). In an aquarium situation Lepidoptera, Diptera and Neuroptera were eaten (Liem 1973).

Impact of Invasive Species
Habitat of R. silus is currently threatened by feral pigs and invasion of weeds (especially mistflower Ageratina riparia) (Hines et al. 1999).

Movements
Rheobatrachus silus is an aquatic species that has never been recorded more than 4 m from water (Ingram 1983). Males, females and juveniles appear to have limited home ranges, although juveniles and gravid females are particularly mobile (females carrying young tend to be sedentary) (Ingram 1983). Only two juveniles out of ten were found to have moved more than 3 m between observations (Ingram 1983). Juveniles were mobile in the sense that they would move to newly created pools, but once stationed there they usually remained in that area (Ingram 1983). During a breeding season, the home range of females and males was estimated to be 0-3.4 m (n=4) and 0-6.2 m (n=10) respectively. Ingram (1983) also reported the distance moved along a stream by seven individuals between seasons. Four females moved 1.8-46 m, and the males moved 0.9-53 m. Only three individuals moved more than 5.5 m (46, 46, and 53 m respectively) and it would appear that they remain within the same pool or group of pools throughout the breeding season, only moving away during periods of high flow or flooding (Ingram 1983). Non-breeding winter habitat is unknown (Ingram 1983).

Trends and Threats
The reason(s) for the disappearance of this species remains unknown (Tyler and Davies 1985). Populations of R. silus were present in logged catchments between 1972 and 1979. Although R. silus persisted in the streams during these activities, the effects of timber harvesting on this aquatic species were never investigated. Its habitat is currently threatened by feral pigs, invasion of weeds (particularly mistflower Ageratina riparia), and altered flow and water quality due to upstream disturbances (Hines et al. 1999.)

References
 

Czechura, G.V. (1991). ''The Blackall-Conondale Ranges: frogs, reptiles and fauna conservation.'' The Rainforest Legacy, Australian National Rainforest Study, Volume 2. Flora and Fauna of the Rainforest. G. Werren and P. Kershaw, eds., Australian Government Publishing Service, Canberra, 311-324.  

Czechura, G.V. and Ingram, G. (1990). ''Taudactylus diurnus and the case of the disappearing frogs.'' Memoirs of the Queensland Museum, 29(2), 361-365.  

Hines, H., Mahony, M. and McDonald, K. (1999). ''An assessment of frog declines in wet subtropical Australia.'' Declines and Disappearances of Australian Frogs. A. Campbell, eds., Environment Australia, Canberra, 44-63.  

Ingram, G. (1983). ''Natural history.'' The Gastric Brooding Frog. M.J. Tyler, eds., Croom Helm, London, 16-35.  

Ingram, G. J., and McDonald, K. R. (1993). ''An update on the decline of Queensland's frogs.'' Herpetology in Australia: A diverse discipline. D. Lunney and D. Ayers, eds., Transactions of the Royal Zoological Society of New South Wales, 297-303.  

Ingram, G.J. (1990). ''The mystery of the disappearing frog.'' Wildlife Australia, 27(3), 6-7.  

Ingram, G.J. (1991). ''The earliest records of the extinct Platypus Frog.'' Memoirs of the Queensland Museum, 30(3), 454.  

Liem, D.S. (1973). ''A new genus of frog of the family Leptodactylidae from south-east Queensland, Australia.'' Memoirs of the Queensland Museum, 16(3), 459-470.  

Meyer, E., Hines, H., and Hero, J.-M. (2001). ''Southern Gastric Brooding Frog, Rheobatrachus silus.'' Wet Forest Frogs of South-east Queensland. Griffith University, Gold Coast, 34-35.  

Richards, S. J., McDonald, K. R., and Alford, R. A. (1993). ''Declines in populations of Australia's endemic rainforest frogs.'' Pacific Conservation Biology, 1, 66-77.  

Tyler, M.J. (1989). Australian Frogs. Penguin Books Australia Ltd., Victoria.  

Tyler, M.J. and Carter, D.B. (1982). ''Oral birth of the young of the gastric-brooding frog Rheobatrachus silus.'' Animal Behaviour, 29, 280-282.  

Tyler, M.J. and Davies, M. (1983). ''Larval development.'' The Gastric Brooding Frog. M.J. Tyler, eds., Croom Helm, London, 44-57.  

Tyler, M.J. and Davies, M. (1983). ''Superficial features.'' The Gastric Brooding Frog. M.J Tyler, eds., Croom Helm, London, 5-15.  

Tyler, M.J. and Davies, M. (1985). ''The Gastric Brooding Frog.'' Biology of Australasian Frogs and Reptiles. G. Grigg, R. Shine, and H. Ehmann, eds., Royal Zoological Society of New South Wales, Sydney, 469-470.  

Tyler, M.J., Shearman, D.J.C., Franco, R., O'Brien, P., Seamark, R.F., and Kelly, R. (1983). ''Inhabitaion of gastric acid secretion in the Gastric Brooding Frog, Rheobatrachus silus.'' Science, 220, 609-610.

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