NSW National Parks and Wildlife Service, July 2001
ISBN 0 731 36275 6
The Yellow-spotted Bell Frog and the Peppered Tree Frog are two frog species endemic to the highlands and tablelands of New South Wales. The Yellow-spotted Bell Frog also occurs in the Australian Capital Territory. Neither species has been definitely recorded in the wild since the mid 1970s, and concerns are held for their continued survival. In a formal response to these concerns, both species have been listed under the NSW Threatened Species Conservation Act 1995 (TSC Act). The aim of this recovery plan is to assist in returning these two species to a position of viability in nature.
The Yellow-spotted Bell Frog (Litoria castanea) (Steindachner 1867) is a large (53 to 85 mm) terrestrial hylid frog belonging to the Australian Bell Frog complex. It is known from the New England Tableland and South Eastern Highland biogeographical regions of south-eastern Australia (Heatwole et al.1995; Osborne et al.1996). Thomson et al. (1996) documented morphological differences between the New England Tableland and South Eastern Highland populations, but concluded that insufficient information was available to warrant recognition of the two forms as distinct species. The Yellow-spotted Bell Frog is distinguished from other species of Bell Frogs by the fully webbed toes and the presence of black and yellow marbling on the ventral surface of the legs (Thomson et al. 1996).
The species has a restricted distribution on the New England Tableland, with all known locations occurring in an area approximately 50 km by 25 km in an altitudinal range between 1000 and 1500 m Australian Height Datum (AHD) (Ehmann 1997). The species' distribution on the South Eastern Highlands was described by Osborne et al. (1996) as ranging from Lake George south to the Bombala area in an altitudinal range between 700 and 800 m AHD. Previously undocumented photographic records of a Litoria castanea-like Bell Frog from near Orange and Bathurst in central western NSW in the late 1960s to mid 1970s may extend the known distribution of the species to include the northern part of the South Eastern Highlands (D. Binns pers. comm.; White and Pyke 1999). The distribution of records of the species is shown in Figure 1.
The Peppered Tree Frog (Litoria piperata) (Tyler and Davies 1985) is a small (20 to 27mm) hylid frog belonging to the leaf green tree frog species complex. It is distinctive from other related species because of its small size, dorsal colour pattern of darker brown-grey peppering on a dark green background and lack of an obvious lateral stripe.
The Peppered Tree Frog occurs only within NSW with a geographic range extending from south of Armidale to the Gibraltar Range, comprising the headwaters of numerous rivers over an altitude range from 800 to 1000 m AHD. The distribution of records of the species is shown in Figure 2.
There have been no confirmed records of the Yellow-spotted Bell Frog in the wild since 1973 (Mahony 1996). The species is currently listed as critically endangered (category A1ac) on the IUCN Red List (International Union for the Conservation of Nature 1997).
The Peppered Tree Frog has not been definitely recorded in the wild since the collection of the type series in 1973; however, some populations of uncertain taxonomic status have been detected recently adjacent to and to the north of its historic range, which may prove to be the species. The Peppered Tree Frog is currently listed as critically endangered (category A1ac) on the IUCN Red List (International Union for the Conservation of Nature 1997).
Concern is currently held for the continued survival of both the Yellow-spotted Bell Frog and the Peppered Tree Frog; however, insufficient survey has been undertaken to date to discount the possibility of small populations persisting in remote or unsurveyed areas.
The Yellow-spotted Bell Frog is listed as an endangered species on both the TSC Act and the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act).
The Peppered Tree Frog is currently listed as a vulnerable species on both the TSC Act and the EPBC Act.
The habitat of the Yellow-spotted Bell Frog comprises ponds, wetlands and slowly moving streams with abundant marginal growth of bulrushes and other vegetation (Heatwole et al. 1995; Tyler 1997). Gillespie et al. (1995) noted that the southern population occurred in both woodland and improved pastoral areas. The lagoons of the New England Tableland and Monaro Plateau may have evolved in a similar manner (Walker c. 1970), suggesting a possible geomorphological factor in the species' distribution.
Behaviour and ecology appears to be similar to other Bell Frog species. Courtice and Grigg (1975) noted that the Yellow-spotted Bell Frog could be found at night on reeds, that males called while floating in open water, that adults were known to bask in the sun during the day, usually on grassy banks or emergent reeds, and that adults over-wintered in hollow logs and in earth amongst the roots of fallen trees. It is presumed that the breeding biology of the Yellow-spotted Bell Frog is similar to that of other Bell Frogs (Courtice and Grigg 1975). Breeding activity of these species occurs during the warmer months, usually following reasonable rainfall. The frogs breed in still or slowly flowing water bodies, laying large spawn masses on the water surface, usually attached to emergent vegetation. Osborne et al. (1996) reported the southern population calling at water temperatures ranging from approximately 13 to 18o C.
The Peppered Tree Frog has been collected from rocky streams flowing eastward from the New England Tableland within an altitude range of 800 to 1010 m AHD (Mahony 1996). The general area in which this species has been recorded has been referred to as the "dry eastern escarpment" (NPWS 1994). Common streamside vegetation at sites where records were made includes Lomandra, Leptospermum and Casuarina (Mahony 1996).
Very little is known about the ecology of the Peppered Tree Frog. Adults are active in bushes or on rocks at the edge of creeks and on one occasion an aggregation of 22 animals was found by day in cracks in a dead tree limb next to a stream (Webb 1973). Nothing is known of the site of egg deposition or larval ecology of the species. It is presumed breeding activity occurs during the warmer months, following reasonable rainfall, although there are no reports of male mating calls.