Taudactylus acutirostris (Andersson 1916)

Population and DistributionTaudactylus acutirostris was widely distributed from Mt Graham to the Big Tableland, n. Qld, at altitudes of 300 to 1300 m (McDonald 1992). The area of occurrence of the species was about less than 9,000km2 (Hero et al. in press). A conspicuous inhabitant of upland rainforest streams because of its diurnal habits and former abundance, the species started disappearing in the s. part of its range in 1988 and had disappeared from s. of the Daintree R. by 1992 (Richards et al. 1993). In the past the species was considered locally abundant and in 1989, 48 calling males were recorded along a 100 m stream transect (Richards et al. 1993). When surveys of the site were undertaken in 1990, only one adult and several tadpoles were located (Richards et al. 1993). The decline of this species is well documented and, in approximately five years from 1988 to 1993, it disappeared from an area spanning about 2o30’ latitude (Ingram 1993). Sightings of a single individual in a small tributary of the South Johnstone R. in 1996 (Marshall 1998), and in 1997, a gravid female seen near Mt Hartley (Hero et al. 1998), are the only records of the species since 1994 (Hero et al. in press). Taudactylus acutirostris was formerly known from Lumholtz, Wooroonooran, Daintree, Crater, Cedar Bay, and Tully Falls NP, Timber Reserve (165 Monkhouse), Lamb Range, Malbon Thompson Range, Herberton Range, Ravenshoe, Kirrama Range, Mt Fisher, Maalan, Mt Lewis, and Windsor SF, SF (757 Japoon) (Tyler 1997). HabitatTaudactylus acutirostris was a habitat specialist, endemic to the W.T. Bioregion (Williams & Hero 1998; 2001) occuring along small creeks in rainforest and wet sclerophyll forest above 300 m (Liem & Hosmer 1973). The species was seen on the rocks during the day near swift-flowing streams or in the rainforest leaf litter during wet weather (McDonald 1992).

ReproductionMales call during the day, from first light to early evening, near rainforest streams from beneath rocks or leaves (McDonald 1992). Males appear to establish territories, possibly as a response to seemingly low numbers of females (Dennis 1982). Breeding has been observed from late Nov. through to Jan. (Liem & Hosmer 1973). Eggs are laid as a gelatinous clump of about 25-40 eggs (2.2-2.7mm diameter) amongst rock in the water usually in heavily shaded locations (Liem & Hosmer 1973). Liem and Hosmer (1973) described that tadpole of the species as lotic benthic. Tadpoles generally inhabit debris in pools or slow flowing sections of stream (Liem & Hosmer 1973). Invasive speciesFeral pigs are a potential cause of riparian habitat damage and adult frog mortality (Richards et al. 1993). The activity of feral pigs has been recorded to have increased over the period 1989-1992 in an area previously inhabited by T. acutirostris (Richards et al. 1993). There is very little research, however, into the impact of feral pigs on native frog populations (Richards et al. 1993).MovementsIndividuals have been seen basking on rocks beside the stream and also forage along the sides of creeks and nearby forest floor (Ingram 1980). Taudactylus acutirostris has also been found long distances away from water during wet weather (Hero & Fickling 1994).

The cause(s) of the decline remains unknown. Richards et al. (1993) found no obvious evidence that drought, floods, habitat destruction or pollution by pesticides, inorganic ions or heavy metals were responsible for the population declines. Big Tableland, the area where T. acutirostris was at its highest density in 1991-1992, has been mined since 1887 and logging ceased in that area in 1963 (Richards et al. 1993). Current research is examining the possibility that disease, such as a viral infection or Chytrid fungus, may have caused the decline of this species (Berger et al. 1999). The effects that having very small isolated populations may have on the recovery of the species remain largely unknown, but may include low genetic variability, increased susceptibility to disease and general demographic instability (Hero et al. 1999).