Northern Tinker Frog

Population and DistributionTaudactylus rheophilus is restricted to four mountaintops from Thornton Peak to Mt Bellenden Ker, n. Qld, at altitudes of 940-1400 m (McDonald 1992; Hero et al. 1998). The area of occurrence of the species is less than 5,000 km2 (map in McDonald 1992). Taudactylus rheophilus has undergone a sudden range contraction and had apparently disappeared by Oct. 1991 (Richards et al. 1993). After a period of apparent absence, five individuals were heard calling in a small, high altitude tributary of the Mulgrave R., and a further seven individuals were heard calling and one captured in a small, high altitude tributary of the Mitchell R., Mt Carbine (Marshall 1998). Further records of the species from the s.e. slope of Mt. Bellenden Ker (Hero et al. 1998) include a single juvenile in Feb. 1998 (Hero et al. 1998) and 3-5 individuals in Dec. 2000 (Freeman 2000) at approximately 1400 m. Taudactylus rheophilus was formerly known from Daintree, and Wooroonooran NP and Lamb Range SF (Tyler 1997). The species is currently known at Mt. Lewis SF and Bellenden Ker NP (Freeman 2000; Hero et al. in press).HabitatTaudactylus rheophilus is a montane specialist, endemic to the W.T. Bioregion (Williams & Hero 1998; in press) occuring along rocky streams in upland rainforest (Liem & Hosmer 1973). It is usually found under rocks and logs beside fast-flowing streams and prefers seepage and trickle areas near streams (McDonald 1992). Individuals recorded in 1996 were found hidden from view in small gaps beneath or between boulders that were at least 1 m in diameter (Marshall 1998). On juvenile on Bellenden Kerr was captured from under a small rock approximately 30cm in diameter, in the streambed (Hero pers. obs.).

ReproductionTaudactylus rheophilus is active all year round (Richards et al. 1993) and calls day and night but mainly during the day (Ingram 1980). Male calling sites are usually under boulders, rocks or roots and individuals may be partially submerged (Ingram 1980; Marshall 1998). Egg masses and tadpoles of the species have not been identified (Liem & Hosmer 1973; McDonald & Alford 1999), but large eggs (1.8-2.4mm diameter), numbering 35-50 have been found in gravid females (Liem & Hosmer 1973). Juveniles have been collected in Dec. and May (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. rheophilus (Richards et al. 1993). There is very little research, however, into the impact of feral pigs on native frog populations (Richards et al. 1993).MovementsTaudactylus rheophilus displays an strong association with streams and is found within the stream banks throughout the year (McDonald & Alford 1999).

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. Current research is examining the possibility that disease, such as a viral infection or Chytrid fungus, may have contributed to 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. in press).