Sharp snouted dayfrog
Sharp snouted dayfrog. Photo: SJ Richards
Common name: sharp snouted dayfrog
Scientific name: Taudactylus acutirostris
Family: Myobatrachidae (Australian water frogs)
Conservation status: This species is listed as Endangered in Queensland (Nature Conservation Act 1992) and Extinct nationally (Environment Protection and Biodiversity Conservation Act 1999). It is considered a low priority under the Department of Environment and Heritage Protection Back on Track species prioritisation framework.
The sharp-snouted dayfrog is a small frog with narrow wedge shaped snout, with males between 18-25 mm and females 22-31 mm long. Adult males weigh up to 1.6 g and females 2.5 g (McDonald and Alford 1999). Its dorsum (back) is greyish olive to dark chocolate brown, and it may have dark V or W shaped markings. A broad, dark grey or black band, bounded above by distinct pale line, runs laterally from the level of the eye to the groin.
The frog’s hind legs have darker cross bands, sometimes barely detectable, but usually quite conspicuous. The ventral (abdominal) surface is greyish white with dark flecks and blotches. The rear part of ventral surface and underside of the limbs are olive-yellow and there is a distinct white patch edged with black at base of each forelimb. The lower jaw is edged with black. The frog’s skin is smooth above and below, with tubercles arranged in a triangle or ridges on the lower back, and there's a distinct dorso-lateral (back and side) skin fold. Its fingers and toes have slightly expanded toe pads, and are fringed but lack webbing (Liem & Hosmer 1973, Dennis 1982, Cogger 2000).
Habitat and distribution
Sharp snouted dayfrogs are generally found among rocks and leaf litter along the edges of rainforest streams, though in wet weather they may be found some distance from the water (K.R. McDonald pers. obs.). It is a diurnal (active both during the day and night) species and will often bask in the sun. The tadpoles are found in debris in pools or slow flowing areas of rainforest streams (McDonald and Alford 1999, K.R. McDonald pers. obs.).
The sharp snouted dayfrog was widely distributed through the upland rainforests of the Wet Tropics, from Mt. Graham near Cardwell to Big Tableland approximately 30km south of Cooktown. The species underwent a dramatic range contraction in the late 1980's, disappearing in the southern parts of its distribution. The last sightings were of an individual reported from Mount Father Clancy, South Johnstone River (Marshall 1998) and a pregnant female near Mt Hartley in 1997 (Hero et al. 1998) but additional surveys have not located the species (Schloegel et al. 2006).
Life history and behaviour
The sharp snouted dayfrog appears to have two calls. A high pitched metallic tinkling sound, "tink tink", repeated several times in quick succession (Liem & Hosmer 1973, Dennis 1982, Richards 1993), and a second call variously described as a popping call (McDonald 1992) or a short, scratchy chirp, "eek eek eek" (Ingram 1980, Richards et al. 1993). Males call from exposed positions on rocks, sand or gravel banks at the waters edge, or from beneath rocks or leaves (Ingram 1980, K.R. McDonald pers. obs.). They call from first light and may continue until early evening. The males establish territories (Dennis 1982). After a period of basking, individuals will move off to forage along the sides of creeks and the rainforest floor nearby. When disturbed they will leap into the water and lie on the substrate for some minutes before resurfacing (Ingram 1980).
Calling males and gravid females have been encountered year round (McDonald and Martin unpublished data). Females lay 25-40 large (2.2-2.7 mm diameter) unpigmented eggs in a large gelatinous clump on the underside of rocks at or below the waterline in flowing creeks (Liem and Hosmer 1973).
Tadpoles are small, with a dark oval body, that is transparent and unpigmented posteriorly with discrete spots across the tail muscle and fins. The tadpole’s eyes are on top of the head and it has two rows of teeth anterior to the jaws and three posterior to the jaws. The inner two rows of teeth are divided in the middle (Liem & Hosmer 1973, Richards 1993).
The sharp snouted dayfrog is one of seven species of frogs occurring in the upland rainforest streams of north-eastern Queensland which have undergone rapid and substantial population declines (Ingram and McDonald 1993, Richards et al 1993, Trenerry et al 1994), with only three individuals reported from the wild since December 1994.
The causes of the decline remain 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. UV impact has been discounted in the tropics (McDonald and Alford 1999). Current research has suggested that the chytrid fungus Batrachochytrium dendrobatidis may have caused the decline of this species (Schloegel et al. 2006). Information on disease investigations and management can be located at the James Cook University website.
The recovery plan for stream-dwelling frogs of the Wet Tropics biogeographic region of north-east Queensland 2000-2004 makes the following management recommendations for the conservation of the sharp snouted dayfrog.
- Monitor historical localities to detect recovery.
- Investigate the role of disease in frog declines.
- Develop and refine captive husbandry techniques for rainforest stream dwelling frogs.
- Train park staff and community volunteers in identification of this species.
- Implement monitoring by park staff of select locations within the national park estate where the sharp snouted dayfrog formerly occurred.
Berger L, Speare R, and Hyatt A 1999. Chytrid fungi and Amphibian declines: Overview, Implications and Future Directions, pp 23-33, in Campbell, A (ed), Declines and Disappearances of Australian frogs, Environment Australia, Department of the Environment and Heritage, Canberra, 234.
Cogger HG 2000. Reptiles and Amphibians of Australia, Reed New Holland, Sydney.
Dennis A 1982. A brief study of the Sharp-snouted Torrent Frog Taudactylus acutirostris. North Queensland Naturalist 50, 7-8.
Hero J-M and Fickling S 1994. A Guide to Stream-dwelling Frogs of the Wet Tropics Rainforests, James Cook University of North Queensland, Townsville.
Hero J-M, Hines H, Meyer,E, Morrison C, Streatfeild C and Roberts L 1998. New records of ‘‘declining’’ frogs in Queensland, Australia, Froglog 29, 1–4.
Ingram G 1980. A new frog for the genus Taudactylus (Myobatrachidae) from mid-eastern Qld with notes on the other species of the genu’. Memoirs of the Queensland. Museum 20 (1) 111-119.
Ingram GJ and McDonald KR 1993. An update on the decline of Queensland's frogs. Pp 297-303, in Lunney, D and Ayers, D (eds), Herpetology in Australia. A diverse discipline, Royal Zoological Society of New South Wales, Mosman, 41.
Liem DS and Hosmer W 1973. Frogs of the genus Taudactylus with description of two new species (Anura: Leptodactylidae), Memoirs of the Queensland Museum 16 (3), 435-457.
Marshall CJ 1998. The reappearance of Taudactylus (Anura: Myobatrachidae) in north Queensland streams, Pacific Conservation Biology 4, 39-41.
McDonald KR 1992. Distribution patterns and conservation status of north Queensland rainforest frogs, Conservation Technical Report 1, Queensland Department of Environment and Heritage, Brisbane.
McDonald KR and Alford RA 1999. A Review of Declining Frogs in Northern Queensland, pp14-22, in Campbell, A (ed), Declines and Disappearances of Australian frogs. Environment Australia, Department of the Environment and Heritage, Canberra, 234.
Richards SJ, McDonald KR, Alford RA 1993. Declines in populations of Australia's endemic tropical rainforest frogs, Pacific Conservation Biology 1, 66-77.
Schloegel LM, Hero J-C, Berger L, Speare R, McDonald K and Daszak P 2006. The Decline of the Sharp-Snouted Day Frog (Taudactylus acutirostris): The First Documented Case of Extinction by Infection in a Free-Ranging Wildlife Species?, EcoHealth 3, 35–40.
Trenerry MP, Laurance WF, and McDonald KR 1994. Further evidence for the precipitous decline of endemic rainforest frogs in tropical Australia, Pacific Conservation Biology 1, 150-153.
Tyler MJ 1997. The Action Plan for Australian Frogs, Environment Australia, Canberra.
Tyler MJ and Knight F 2009. Field guide to the frogs of Australia, CSIRO Publishing, Collingwood Victoria.