Action Statement FloraFlora and and Fauna Fauna Guarantee Guarantee Act Act 1988 1988 No. No. ### 112 Spotted Tree Frog Litoria spenceri Description and Distribution The Spotted Tree Frog Litoria spenceri (Dubois 1984) is a medium-sized species in the Family Hylidae. Females may attain a length of 61mm (snout–vent), while males are smaller, reaching 50mm (Watson et al. 1991). The dorsum is highly variable: it may be pale brown, bright green to olive-grey, with or without darker blotches, usually with numerous small, raised ‘warts’. The ventral surface is pale and granular, often becoming flushed with pale orange towards the rear and on the underside of the hind limbs. Toes and fingers are distinctly flattened, with the discs moderately expanded; the fingers have distinct basal webbing Spotted Tree Frog Litoria spenceri and the toes are fully webbed. The head is broad (photograph by Graeme Gillespie) and a distinct fold is present above the indistinct tympanum. The tadpole is free swimming. The body is elongated and flattened, and individuals reach a total length of 40mm prior to metamorphosis. The tail is moderately thick and has a rounded tip. The eyes are dorso-lateral and the mouth is ventral. The oral disc is large relative to other closely related species, and the oral papillae have a wide anterior gap. There are two rows of anterior labial teeth and three posterior rows. The body is dark brown to black above, with fine silver chromatophores extending onto the flanks. Darker spots may be present on the dorsal surface. The ventral surface is darkly pigmented. The tail fin and muscle are covered with fine melanophores Distribution in Victoria (Hero et al. 1995). + before 1985, since 1985 The Spotted Tree Frog is confined predominantly [source: Atlas of Victorian Wildlife, NRE to the north-western side of the Great Dividing Range, between the Central Highlands of Victoria and Mt Kosciusko in NSW. Despite extensive surveys of most major streams within the species’ distribution and recreation/human access, road range, only 12 populations have been located in construction and clearing of stream bank Victoria; these occur in the catchments of 17 vegetation (Gillespie and Hollis 1996). streams (several populations occurring around the Disturbances which might result in changes to the confluences of streams). Two further populations physical or biotic habitat in or adjacent to streams are known from Kosciuszko National Park in NSW, include roading, timber harvesting, eductor including one in the upper Murray River along the dredging, human disturbance (e.g. angling), weed Victorian border. The species seems likely to have invasion, predation by exotic animals (including a limited and fragmented distribution and may introduced fish), impoundments, herbicides, have suffered a significant decline during the past inappropriate fire regimes and possibly grazing. 20 years. Important concerns include changes in flow rates, Spotted Tree Frogs inhabit naturally vegetated, which may affect the viability of eggs or the rocky, swift-flowing upland streams in dissected survivorship of tadpoles; increases in sediment mountainous country, between 280 and 1 110 levels, which may affect the availability of egg- metres above sea level. Frog populations are deposition sites or the survivorship of tadpoles; generally in areas with limited access and and predation of tadpoles by introduced fish, disturbance. Distribution along streams is patchy, which may reduce or preclude recruitment to the most individuals being associated with loose rock adult population. substrates, rocky banks and rapids. Adjacent streamside vegetation is also used for sheltering Remaining populations of L. spenceri are thought and basking. Eggs are deposited under large in- to be quite insular, based upon preliminary genetic stream boulders, and tadpole development occurs examination (Gillespie 1997a). Natural within the stream (Hero et al. 1995, Gillespie recolonisation of adjacent streams is highly 1997a,b). unlikely. The full range of habitats used by the species is Only one of the known Victorian localities is unknown; other species of riparian tree frogs range completely within a permanent conservation widely from streams during the non-breeding reserve, and the population is thought to be extinct period. Spotted Tree Frogs may use similar off- at this locality. All other Victorian localities are stream habitats. The stream environment is used within State Forest, although part of the by this species from October to April; it is not catchments of some are within conservation known what habitats are used at other times. reserves. The Code of Forest Practices for Timber Harvesting (NRE 1996) requires protection of the Current conservation status stream environment and the application of a 20m buffer on either side of permanent streams. ESP Act (1992)…. Endangered Additional protective measures may be needed to NRE (2000)………Critically Endangered ensure protection of Spotted Tree Frog habitat beyond the 20m buffer. The Spotted Tree Frog has been listed as a threatened taxon under the Flora and Fauna In its final recommendation the Scientific Advisory Guarantee Act 1988. Committee (SAC 1991a) has determined that the Spotted Tree Frog is: Reasons for conservation status • in a demonstrable state of decline which is The Spotted Tree Frog is known from only 13 likely to result in extinction; streams (11 in Victoria, two in NSW). Surveys • significantly prone to future threats which are during the past five years have found it along eight likely to result in extinction; and streams in which it had not been recorded before, • very rare in terms of abundance or distribution. but it could not be found along four streams in which it had previously been recorded. The Major Conservation Objectives surveys failed to detect Spotted Tree Frogs at historical sites on a further four streams, but The major conservation objectives are to: located the species elsewhere along those streams • Prevent further loss of populations of this (Gillespie and Hollis 1996, Gillespie 1998). species from Victorian streams, and ensure the This evidence suggests that the Spotted Tree Frog long-term viability of all existing populations may have suffered a general decline in distribution (twelve in Victoria and two in NSW). and abundance. All extant populations appear • Manage the habitat so that there is no more under threat from various disturbances; many than 1% probability of extinction of the species populations are small, and some have declined. An in Victoria within 100 years (as determined by analysis of disturbance histories at individual sites population viability analysis). As a short term indicates an association between the contraction in aim, until detailed ecological information is 2 available to enable such analyses, all extant subsequent recruitment are yet to be investigated. populations should be maintained at least at However, populations do appear to experience their present levels. The long-term aim extremely variable recruitment, and thus might be (dependent upon research findings) may particularly vulnerable to further disturbances. require enhancement of existing populations, Some catchments still supporting Spotted Tree and could conceivably involve reintroduction of Frogs have undergone various disturbances in the the species at sites where it has become extinct. past, and may be able to tolerate low levels of A target of over 200 adult frogs per population these disturbances. However, populations have is desirable; and become extinct in the past, and may do so in the • Identify and control any imposed disturbances future (with little or no possibility of which may potentially affect populations, until recolonisation from other populations) if such time as the actual effects of any such inappropriate levels of disturbance are allowed. disturbances are known. Wider conservation issues Management Issues Research into the Spotted Tree Frog will assist in Ecological issues specific to the taxon the conservation of other riverine frog species in Australia, in particular the Blue Mountains Tree Spotted Tree Frog populations are isolated, Frog Litoria citropa, Leaf Green Tree Frog L. possibly indicating a much wider distribution in phyllochroa, Lesueur’s Frog L. lesueuri and the past with a decline to present levels. The small Southern Barred Frog Mixophyes balbus in Victoria. size and isolation of these populations exposes all populations to risk of extinction from stochastic The sites of extant populations of this frog are events, with little chance of natural re-colonisation. often on streams of high conservation value for other reasons. Other threatened stream or riparian Potentially threatening processes implicated in the flora and fauna (e.g. Barred Galaxias Galaxias decline of this species include disturbance in and fuscus, Mountain Galaxias Galaxias olidus, Central adjacent to streams and in catchments of streams, Highlands Spiny Crayfish Euastacus woiwuru) exist which may result in changes to water flow, water in catchments supporting Spotted Tree Frogs. A quality, stream sedimentation or other changes to broad approach to catchment protection and the physical or biotic habitat (Gillespie and Hollis, management aimed at frog conservation will 1996). These include stream sedimentation and enhance the conservation of these other species. physical disturbances associated with poorly- managed roads or road construction activities, A number of threats to in-stream fauna have been