AMPHIBIAWEB
Litoria spenceri
Spotted Tree Frog, Spencer’s River Tree Frog
family: Hylidae
subfamily: Pelodryadinae

© 2002 Jean-Marc Hero (1 of 1)
Conservation Status (definitions)
IUCN (Red List) Status Critically Endangered (CR)
CITES No CITES Listing
Other International Status None
National Status None
Regional Status None

 

View distribution map using BerkeleyMapper.

   

From the IUCN Red List Species Account:

 

Range Description

This species, an Australian endemic, is restricted predominantly to the western fall of the Great Divide, from Lake Eildon in the Central Highlands of Victoria to Mount Kosciuszko in New South Wales, at altitudes of 200-1,100m asl (Gillespie and Hollis 1996; Victorian Wildlife Atlas unpublished data). The area of occupancy of this species is believed to be less than 5km².

Habitat and Ecology

This species is associated with a range of vegetation communities from montane forest at high altitudes to wet and dry forest at moderate to low altitudes, respectively (Gillespie and Hollis 1996). The extent of riparian forest at known localities ranges from virtually non-existent, with scattered riparian tree or shrub species, to a dense canopy of Leptospermum spp. shading the stream (Gillespie and Hollis 1996). The species is found almost exclusively in association with rock habitats along streams and occurs along sections of streams with steep banks, invariably in steeply dissected country or gorges with numerous rapids and waterfalls (Gillespie and Hollis 1996). L. spenceri is restricted to riffle and cascade stream sections with exposed rock banks, resulting in a highly patchy distribution along most streams (Gillespie and Hollis 1996). Adults and juveniles most likely remain in the vicinity of the stream, rarely venturing far from riparian zone (Gillespie 1997). Frogs have been seen basking on rocks mid-stream (Ehmann, Ehmann and Ehmann 1993). Adults have been found between September and May, and calling males have been heard in October, November and early December (Hero 1990, 1991; Watson et al. 1991; Gillespie 1993) and February (G. Gillespie, in Hero, Watson and Gillespie 1995). Clutches consist of 200-1,000 eggs (Gillespie 1997). Oviposition sites are in narrow spaces beneath large river stones within the stream and eggs are hidden as they adhere to the underside of the rock (Gillespie 2001b). The seasonal distribution of size classes of frogs and breeding activity (Watson et al. 1991; Gillespie 1993) suggest that eggs are laid in late spring/early summer and tadpoles reach metamorphosis in late summer/autumn (Hero, Watson and Gillespie 1995). Hero, Watson and Gillespie (1995) described the tadpole. At lower altitudes, sexual maturity is reached 18 months and 3.5 years after metamorphosis by males and females, respectively (Gillespie 2001a). At higher altitudes, sexual maturity is reached at least 3.5 and 4.5 years by males and females, respectively (Gillespie 1997).

Population

Despite extensive systematic surveys throughout eastern Victoria and southern New South Wales (Watson et al. 1991; Gillespie 1992; Gillespie and Hollis 1996; Hunter and Gillespie 1999) this species has only ever been found in 19 streams, and has always been considered rare (Watson et al. 1991). The species is now believed to be extinct in four of these streams, and has declined substantially in distribution and abundance along most others (Gillespie and Hollis 1996). The remaining streams comprise 12 discrete isolated populations (Gillespie and Hollis 1996; Hunter and Gillespie 1999). Two populations are known to have died out over the past five years. Monitoring has been conducted at eight populations since 1994 and has recently been expanded to include 15 streams (G. Gillespie pers. comm.). With the exception of the historic site on Buffalo Creek, Mount Buffalo National Park, monitoring of sites where it is extinct ceased in 1998 (G. Gillespie pers. comm.). Most extant adult populations have remained relatively stable since 1993; however, a population at Bogong Creek, Mount Kosciuszko National Park suffered a precipitous decline in 1996 (Gillespie 1997). It is at a higher elevation than other populations and was the only high-density population known prior to the decline (Gillespie and Hollis 1996). Gillespie and Hines (1999) estimate the largest population to contain approximately 1,000-1,500 adults in the Upper Goulburn River with the sizes of all other populations comprising less than 1,000 adults.

Population Trend

Decreasing

Major Threats

Declines occurred in the 1970s and early 1980s (Watson et al. 1991). Gillespie and Hollis (1996) suggest that, based upon the known demography of the species, this species probably suffered population declines over a wider area earlier in the 20th century, and possibly late in the 19th century. Human disturbances to streams, such as gold dredging, forest roads and recreational pressures are correlated with the general pattern of decline of this species (Gillespie and Hollis 1996). Trout species (Rainbow Trout Oncorhynchus mykiss and Brown Trout Salmo trutta) occur throughout the geographic range and are able to exert significant predation pressure on larvae (Gillespie 2001a). Trout are believed to be a major cause of population declines of this species (Gillespie 2001a). Several moribund frogs have been located from four populations (Gillespie and Hines 1999) and recently identified as being infected with the chytrid fungus (Berger et al. 1998; Gillespie and Hines 1999). However, the role of the fungus in the population dynamics of this species remains to be resolved (Gillespie and Hines 1999).

Conservation Actions

The range of the species is within a few protected areas. It is listed as Endangered in Australian legislation. A monitoring programme for this species has been established, but further research is required to determine the reasons for the observed declines. Given the possible threat of chytridiomycosis, the establishment of a captive-breeding programme might be required, while in situ conservation measures should include control of invasive trout species at least within protected areas.

Citation

Jean-Marc Hero, Graeme Gillespie, Peter Robertson, Murray Littlejohn, Frank Lemckert 2004. Litoria spenceri. In: IUCN 2014

 

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