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Mixophyes balbus

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA AMPHIBIA ANURA MYOBATRACHIDAE

Scientific Name: Mixophyes balbus
Species Authority: Straughan, 1968
Common Name/s:
English Grey Barred Frog, Silver-eyed Barred Frog, Southern Barred Frog, Stuttering Frog
Taxonomic Notes: This taxon might represent a species complex.

Assessment Information [top]

Red List Category & Criteria: Vulnerable C1+2a(i) ver 3.1
Year Published: 2009
Date Assessed: 2004-04-30
Assessor/s: Gillespie, G., Robertson, P., Hines, H., Lemckert, F. & Hero, J.-M.
Reviewer/s: Chanson, J.S., Cox, N.A. & Stuart, S.N.
Justification:
Listed as Vulnerable because the population size is estimated to number fewer than 10,000 mature individuals, there is a decline of >10% expected over the next three generations, and no subpopulation is estimated to contain more than 1,000 mature individuals.
History:
2002 Vulnerable
1996 Vulnerable
1994 Insufficiently Known (Groombridge 1994)

Geographic Range [top]

Range Description: This species, an Australian endemic, is restricted to the eastern slopes of the Great Divide, from the Cann River catchments in far East Gippsland, Victoria, to tributaries of the Timbarra River near Drake, New South Wales (Gillespie and Hines 1999). It occurs from 20 to over 1,400 m asl, from low to high altitudes from south to north (Gillespie and Hines 1999).
Countries:
Native:
Australia (New South Wales, Victoria - Possibly Extinct)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Mixophyes balbus was formerly more frequently encountered in the northern part of its range than south of Sydney, although this might reflect limited historical searches in the region (Gillespie and Hines 1999). The species has only been found in Victoria on three occasions (Tennyson Creek, Cann River and Jones Creek) and is now thought to be extinct in that state (Gillespie and Hines 1999). The species has declined and disappeared from a number of locations in New South Wales where it was previously common (Mahony 1993, Anstis and Littlejohn 1996, Anstis 1997). Surveys in southeast New South Wales since 1990 have located individuals at only a few sites (Lemckert et al. 1997, Daly 1998). The estimated population number is less than 10,000, and where populations have been recorded recently, the species appears to be in low numbers (Mahony et al. 1997).
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: This species is typically found in association with permanent streams through temperate and sub-tropical rainforest and wet sclerophyll forest, and rarely in dry open tableland riparian vegetation (Mahony et al. 1997), and also in moist gullies in dry forest (Gillespie and Hines 1999). The ecological requirements of adults and larvae are poorly known. In northeast New South Wales, statistical modelling was used to investigate the relationship of this species with 24 environmental predictors (NSW NPWS 1994, in Gillespie and Hines 1999). The species showed a preference for the interiors of large forest tracts in areas with relatively cool mean annual temperatures. These sites are typically free from any disturbance with a thick canopy and relatively simple understorey (Gillespie and Hines 1999). Mixophyes balbus occurs in first order streams and occasionally springs; it is not associated with ponds or ephemeral pools (Mahony et al. 1997). Calling has been recorded from September to April (F. Lemckert pers. comm.). Males call from beside small streams, often from under leaf-litter or within holes (Lemckert and Morse 1999). Reproductive biology is very similar to that of Mixophyes fleayi (Gillespie and Hines 1999). Both species construct a nest in shallow running water that occurs between pools in relatively wide, flat sections of mountain streams (Knowles et al. 1998), and 500-550 pigmented eggs (2.8 mm diameter) are deposited in a shallow excavation in the streambed or pasted directly onto bed-rock (Watson and Martin 1973, Knowles et al. 1998). The stream microhabitats used by this species for oviposition are limited (Knowles et al. 1998). The free-swimming tadpole of the species has been described by Watson and Martin (1973) and Daly (1998). Tadpoles develop in pools and shallow water with the aquatic phase of the life cycle lasting approximately one year (Daly 1998).
Systems: Terrestrial; Freshwater

Threats [top]

Major Threat(s): Several potentially threatening processes have operated at sites where this species has been found, or up-stream in catchments. Logging and associated forest management practices have been carried out in some catchments where M. balbus historically occurred, or currently occurs (Mahony et al. 1997). The health and stability of extant populations in these disturbed catchments is unknown. Forest grazing and land clearance for pasture upstream have also occurred in some catchments (Mahony et al. 1997). Mahony et al. (1997) report that the species is not known from any localities with disturbed riparian vegetation or significant human impacts upstream. This might indicate that the species is highly sensitive to perturbations in the environment. However, populations of this species have also disappeared in catchments with seemingly minimal human disturbance (Mahony et al. 1997). Also, Lemckert (1999) was unable to detect a negative impact of selective logging on this species. Trampling by domestic stock is likely to have deleterious impacts on oviposition sites of the species (Knowles et al. 1998). However, different degrees of suspended sediments have not been found to affect growth and survivorship of tadpoles (Green et al. 2004). Mixophyes balbus tadpoles have been found in sympatry with native fish, and probably have survival strategies to avoid predation by them (Gillespie and Hines 1999). However, the impact of introduced fish, such as Eastern Gambusia (Gambusia holbrooki), carp (Cyprinus spp.) and salmonids is unknown (Gillespie and Hines 1999). Mahony et al. (1997) did not observe introduced fish at any sites where they found M. balbus. In other reports though, introduced fish (salmonids) have been recorded at sites where M. balbus has declined (Anstis 1997). However, M. balbus has also disappeared from many streams that do not contain introduced fish species (Gillespie and Hines 1999), and so disease, such as chytridiomycosis, might also be a factor in its decline.

Conservation Actions [top]

Conservation Actions: Disease protocols are in place. A Recovery Plan is being developed for this species. Its range includes a few protected areas and it is protected wherever it occurs in State Forests. There is a cooperative program between Melbourne Zoo and the NSW North-East Threatened Frog Recovery Team to develop husbandry protocols for the species. It is now thought that this species encompasses more than one taxonomic form. The Zoo has frogs from northern and southern populations and has bred the former.
Citation: Gillespie, G., Robertson, P., Hines, H., Lemckert, F. & Hero, J.-M. 2009. Mixophyes balbus. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 20 April 2014.
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