Orange Bellied Frog

Population and Distribution Geocrinia vitellina is confined to a 6.3 km2 area east of the Leeuwin-Naturaliste Ridge in the extreme s.w. of WA (Tyler 1997). Only six populations of G. vitellina are known (Roberts et al. 1999). Population estimates are available for Spearwood North and South from 1992 to 1998 (Driscoll 1998, 1999; Roberts et al. 1999) and Geo Ck from 1993 to 1994 (Driscoll 1998, 1999). Estimates of calling males for the three locations varied between approximately 30 and 160 individuals (Driscoll 1998, 1999; Roberts et al. 1999). Populations at Spearwood varied in size over the survey period with no obvious cause of decline or increase at either site (Roberts et al. 1999). In 1994 the maximum total number of adults of the species was estimated at 2,230 frogs (Wardell-Johnson et al. 1995 in Roberts et al. 1999). HabitatGeocrinia vitellina is wholly distributed within SF (Tyler 1997). However, most of the species range has been recommended for gazettal as a Nature Reserve as part of the Regional Forest Agreement.Wardell-Johnson and Roberts (1993) described the biogeographic barriers separating the distributions of four allopatric species from the Geocrinia rosea complex. Both G. alba and G. vitellina occur in permanently moist sites in relatively dry and seasonal climatic zones and their distributions are separated by 9 km of lateritic uplands and narrow valleys (Wardell-Johnson & Roberts 1993). Geocrinia vitellina occupies six unconnected and undisturbed areas of riparian vegetation at an elevation of 120 m in broad u-shaped valleys where there is marked topographic relief (Tyler 1997). The species is abundant at seepages but rare on the valley floor (Tyler et al. 1994).

ReproductionMales call from small depressions in clay under dense vegetation cover. Egg are deposited in small depressions and are often associated with calling males. Eggs hatch and the tadpoles develop in a jelly mass with no free swimming of feeding stage.[Roberts et al. 1990]Invasive speciesFeral pigs have been identified as a potential threat to the species, however, pig control has been conducted in the area and there has been no evidence of pig damage at any known population of this species (Roberts et al. 1999).MovementsGenetic structuring of populations indicate that movement is extremely limited with little or no migration among populations for any life stage or sex, even at very local scales (Driscoll 1997, 1998). The genetic differences throughout the range of the species are very large, especially given the small distances between populations (maxima 4 km) (Driscoll 1998). While a precise value for the rate of dispersal cannot be calculated, the conclusion that individuals do not disperse far from their natal swamp is consistent with a mark-recapture study of G. alba and G. vitellina (Driscoll 1997). Driscoll (1997) found that 97% of adult male frogs were displaced less than 20 m over one year, while the maximum displacement was 50 m. Migration rates between populations are so low that any local extinctions are unlikely to be countered in the short term by recolonisation (Driscoll 1998).

No populations are known to have gone extinct, however, populations burnt in 1997 are currently the subject of monitoring to assess their status (Roberts et al. 1999). All six known populations occur in State Forest or areas proposed as conservation reserves and are under no immediate threat from clearing or logging activity (Roberts et al. 1999). Potential threats to G. vitellina include inappropriate fire management and feral pigs, however, there has been no evidence of pig damage at any known population of this species (Roberts et al. 1999).A fire exclusion zone has been established for part of the range of this species (covering about half of the geographic range and containing approximately 80% of the adult frog population). The remainder of the range is subject to fuel reduction burning which is restricted to spring on an eight year cycle (Roberts et al. 1999). Importantly, however, since establishment 85% of the fire exclusion zone was burnt at varying intensities in a 1997 wild fire (an escape from a fuel reduction burn in an adjacent block) (Roberts et al. 1999). As there are large genetic differences between populations, many populations will need to be conserved in order to maintain genetic variation in the long term (Driscoll 1998). Maintaining many small populations is an effective way of preventing allelic loss from the species as a whole and is likely to be more effective than conserving a smaller number of large populations provided that small populations do not become extinct, which would result in loss of unique genetic variants (Driscoll 1998). The likely biogeographic history of G. vitellina suggests that contractions and expansions of geographic range may be a natural phenomenon, and that they play an important role in the evolution of the species (Driscoll 1998). Therefore, if evolutionary processes are to be maintained, range changes need to be accommodated in the long term. For range expansion to take effect, unoccupied swamps need to be available, and there needs to be suitable habitat between sites through which frogs can migrate (Driscoll 1998).Conservation concern is primarily a result of the restricted range of this species (Roberts et al. 1999).

The Coolgardie woodlands is the largest reamaining intact Mediterranean climate woodland on Earth, and this ecoregion hxhibits high species richness, in spite of the superficial appearance of a desiccated land. Soil fertility of this ecoregion is generally quite low, so that agriculture has never played a significant role; however, discovery of gold in the year 1892 generated a wave of alluvial mining, whose peak supported hundreds of miners and support personnel.

Due to the extreme geological stability and absence of glaciation since the Carboniferous period, the soils are low in nutrients and often high in salinity; therefore, the region is considered to have to lowest sheep stocking capacity of any ecoregion on Earth for a vegetative covered area. Maximum sheep stocking carrying capacity of one sheep per square mile is a norm.

Many of the ecoregion's soils are saline and calcareous, and plant species here have had to adapt to the poor soils and harsh, hot arid climate to survive. Much of the soil composition of the northern Coolgardie can be classifed as brown calcareous earths; however, the eastern portions manifest more shallow skeletal calcareous loams, and in the south duplex mallee soils dominate.Prominent vegetation includes mallee, certain eucalyptus species and a wide spectrum of plants from the genus Eremophila.

There have been 344 vertebrate species recorded in the Coolgardie woodlands, although faunal vertebrate endemism is low.Special status birds within the ecoregion are: the Near Threatened Australian bustard (Areodotis australis), the Near Threatened black-tailed godwit (Limosa limosa), the Near Threatened buff-breasted sandpiper (Tryngites subruficollis), the Near Threatened grey falcon (Falco hypoleucos), the Vulnerable malleefowl (Leipoa ocellata) and the Near Threatened western whipbird (Psophodes nigrogularis).

Amphibians occurring in the Coolgardie woodlands which have been classified as threatened or endangered are represented by the Vulnerable Australian ground froglet (Geocrinia vitellina). Special status reptiles found in the ecoregion are: the Near Threatened Bardick snake (Echiopsis curta) and the Endangered woma (Aspidites ramsayi). Special status mammals of the Coolgardie are represented by the Vulnerable plains mouse (Pseudomys australis) and the Near Threatened western quoll (Dasyurus geoffroii).

Anstisia vitellina, commonly known as the orange-bellied frog, is a species of frog in the family Myobatrachidae. It is endemic to a 20 hectare area near Margaret River in Southwest Australia. It is vulnerable to extinction due to fire and the destruction of habitat caused by feral pigs.