Population and Distribution
Nyctimystes dayi occurs throughout the Wet Tropics Bioregion from Paluma to Cooktown, n. Qld, at altitudes between 0 and 1200 m (McDonald 1992). The area of occurrence of the species is approximately 9000 km2 (M. Cunningham pers. comm.). The species includes two divergent genetic lineages separated by Barron Ck - diversity within each lineage is very low (M. Cunningham pers. comm.). Nyctimystes dayi has disappeared from upland sites throughout the Wet Tropics and was last recorded from Mt Spec SF in 1990 and the Kirrama Range in 1989 (Richards et al. 1993; M. Cunningham pers. comm.). Richards et al. (1993) noted that the species was still common at most foothill and lowland sites and recorded adults and larvae from upland sites north of the Daintree R. These populations subsequently disappeared in 1992 and 1993 (M. Cunningham pers. comm.). At one monitoring site at O’Keefe Ck, Big Tableland, N. dayi has occasionally reappeared near a site at an altitude of 400m, but has not established resident populations and is absent from a monitoring site at 680 m (McDonald & Alford 1999). Interestingly, the lowland and foothill populations still exist (McDonald & Alford 1999). Nyctimystes dayi is known from Cedar Bay, Crater, Daintree, Lumholtz, Millstream, Paluma Range and Wooroonooran NP, Daintree Timber Reserve (165 Monkhouse), Lamb Range, Mt Lewis, Mt Spec and Windsor Tableland SF, SF 768 Alcock, Crystal Cascades NP (Tyler 1997), Wallaman Falls (Seaview), Palmerston NP (M. Cunningham pers. comm).Habitat
Nyctimystes dayi is a rainforest specialist, endemic to the W.T. Bioregion (Williams & Hero 1998; 2001) associated with rainforests and rainforest margins (Czechura et al. 1987). In montane areas the species prefers fast-flowing rocky streams although they also frequent slower watercourses where ample vegetation exists along the margins (Czechura et al. 1987). At low elevations, N. dayi favours rock soaks, narrow ephemeral streams and rock outcrops in larger watercourses (Czechura et al. 1987). It may also be found on rocks, boulders and vegetation in or adjacent to streams (Czechura et al. 1987).

• Terrestrial
• Freshwater

The tadpoles of torrent-stream frogs stick to rocks in fast-flowing waters via enlarged mouths with suction lips.

Reproduction
Nyctimystes dayi is a spring/summer breeder (Davies & Richards 1990) with peak breeding activity from Oct. to Apr. (Hero & Fickling 1997; Hodgkinson & Hero in press). Davies and Richards (1990) provide a detailed description of the developmental biology of the species. Males call at night from rocks and low foliage along rapidly-flowing stretches of creek. The competition for females may necessitate territorial behaviour in males, as they have never been found calling in a group or within 1 m of another male (Hodgkinson & Hero in press). Amplexus is axillary and eggs are laid in a cohesive clump under rocks in rapidly-flowing water (Czechura et al. 1987). A clutch collected contained 107 unpigmented eggs (egg diameter 2.3-2.6mm, capsule diameter 3.3-3.5mm, n=5) (Davies & Richards 1990). Tadpoles can be found on or under rocks in fast flowing sections of stream and show adaptations to living in torrent, such as large suctorial mouthparts and muscular tails (Davies & Richards 1990; Fickling & Hero 1994). After hatching they aggregate under a rock until their digestive tracts are fully formed (Davies & Richards 1990). After several days they begin to graze on benthic algae and may drift downstream (Davies & Richards 1990). Tadpoles from eggs laid in early summer complete development in 3-4 months (Davies & Richards 1990). Those eggs laid in late summer may overwinter and metamorphose the following summer (Davies & Richards 1990). Feeding
Adults feed indiscriminately on both aquatic and terrestrial invertebrates (Hodgkinson & Hero in press). Their principal diet includes: Coleoptera, Aranea, Odonate larvae, Blattodea and Diptera (Hodgkinson & Hero in review).Invasive species
Feral 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 N. dayi (Richards et al. 1993). There is very little research, however, into the impact of feral pigs on native frog populations (Richards et al. 1993).Movements
Nyctimystes dayi displays a moderate association with streams and is found with some reliability within the stream banks over an extended season (McDonald & Alford 1999). Hodgkison and Hero (in press) described the movements of the species. Nyctimystes dayi moves towards rainforest streams where it is known to breed only during the warmer wet season/early dry season. Adult males are most abundant at the stream during this time, presumably because they are holding breeding territories. Juveniles and females are rarely encountered. Changes in the stream temperature seem to influence nocturnal activity and trigger the movement of the species in relation to the stream. The location of this species during non-breeding periods remains unknown (Hodgkison & Hero in press).

The reason(s) for the decline of the species are largely unknown. Although in the past habitat destruction may have been a factor, clearing or logging has not taken place in the Wet Tropics World Heritage Area, where the species occurs, since 1988 (McDonald & Alford 1999). Richards et al. (1993) first noted a decline of the species in pristine rainforest habitats in 1989. Richards et al. (1993) reject drought, floods, habitat destruction or changes in water quality (pH, conductivity, temperature, dissolved oxygen and metal ions) as the primary causes of the decline. However, in a study by Hodgkinson and Hero (in press) cold temperatures were found to reduce the activity of N. dayi and it was suggested that prolonged exposure to cold, dry conditions (particularly at high altitudes) may inhibit the breeding and survival of the frogs and influence recruitment in local populations. Current research is examining the possibility that disease, possibly a virus or Chytrid fungus, may have contributed to the decline of this species (Berger et al. 1999, McDonald & Alford 1999).