Green and golden bell frog (Litoria aurea)
|Also known as:||golden bell frog, smooth swamp frog, swamp frog|
|Size||Maximum adult male length: 70 mm (2)|
Maximum adult female length: 90 - 100 mm (2)
Maximum tadpole length: 65 - 80 mm (2)
Classified as Vulnerable (VU A2abce) by the IUCN Red List (1) and listed on Schedule 1 of the New South Wales Threatened Species Conservation Act 1995 (3). Listed as near threatened under the Victorian Flora and Fauna Guarantee Act (1998) (6).
The green and golden bell frog belongs to the tree frog family (Hylidae) (4) and was once one of the most common frogs in south-east Australia (5). Unfortunately it has undergone a major decline, and is now classified as globally Vulnerable by the IUCN Red List of Threatened Species (1). It is a large, stout-looking frog, with bright pea-green upperparts blotched with metallic brassy-brown or golden markings (2). A creamy-white stripe bordered below with black and above with gold extends from behind the eye to the groin. The belly is cream or white in colour, and has a granular texture (3). The legs are green and gold and the inside thigh and groin are electric-blue (2). Males are smaller than females and develop a yellowish throat when mature (2). When in breeding condition, males have swollen thumbs as they develop ‘nuptial pads’, used to grip females during mating (3). The large tadpoles have deep bodies and high tail fins (3). Just before their limbs form, they begin to develop the greenish colouration of the adults (2). This frog produces a deep, growling call which has been described as a four-part ‘craw-awk, crawk, crok crok’ (4) that has been likened to the sound of a motorbike changing gears (5).
This species is found in eastern and south-eastern New South Wales, the Australian Capital Territory and eastern Victoria, Australia (3). In New South Wales and Victoria this species has undergone a severe decline in terms of both range and abundance since the 1960s (1). It has disappeared from all highland areas over 250m except for the population in the Australian Capital Territory, and coastal populations have become small and highly isolated. A study of subpopulations throughout the region has shown that many are worryingly small (less than 20 adults) (1). This frog still survives in some areas of Sydney, one of which was the proposed site for the tennis courts for the 2000 Sydney Olympics. After the frog was discovered on the site, the courts were built elsewhere, and the species has been monitored at the site ever since (5). This frog has been introduced to New Zealand and some Pacific Islands (3).
Although a member of the tree frog family, this species tends to spend most of its time on the ground or in water (4). Its habitat requirements have been difficult to pin-point, as it has been found in a huge range of water bodies except fast-flowing streams (1). It is most typically found in short-lived freshwater ponds that are still, shallow and unpolluted, and it tends to avoid waters supporting native fish (3). Foraging and basking habitats are characterised by the presence of dense vegetation that protrudes out of the water; furthermore, grassy habitats are usually close at hand to provide suitable terrestrial feeding grounds (3).
The green and golden bell frog is unusual in that it is often also active during the day. They breed in the warmer months from October to March (4). During the breeding season, males tend to call whilst partially submerged in the water (4) and females lay 3,000 to 10,000 eggs in gelatinous masses that initially float, but sink up to 12 hours after laying. Two days later the tadpoles hatch out and on average they will have fully metamorphosed into young froglets after a further two months (3), although the development period depends on the temperature (2).
The voracious adults have a very broad diet, including insects and other frogs, even of the same species (4). The tadpoles feed on detritus, algae and bacteria (3). Natural predators include wading birds and snakes, and the tadpoles are taken by tortoises, eels and other fish (2) as well as a range of invertebrate predators (7).
There are many factors thought to be responsible for the dramatic decline of this species. Habitat fragmentation, the introduction of predatory fish and alteration of drainage regimes are all thought to be involved. Many studies have shown that losses of this frog are closely related to the introduction of the ‘mosquito fish’ (Gambusia holbrooki), native to North America and introduced as an attempt to control mosquito larvae. Laboratory studies have demonstrated that the tadpoles of the green and golden bell frog are extremely susceptible to predation by this fish (3). Other factors thought to affect this species include predation by introduced mammalian predators such as cats and foxes, changes to the quality of water, herbicide use, and loss of habitat through the destruction of wetlands (2). However, the recently identified Chytrid fungus appears likely to have led to at least some and perhaps most of the major declines observed through the 1970s and 1980s (7).
The green and golden bell frog has been the subject of much research and monitoring. This is very important, as well-informed conservation measures are likely to be more effective (1). Current work is focusing on the development of management measures to keep the introduced mosquito fish under control. Furthermore, strategies are being devised that will allow the development and improvement of suitable habitat in order to increase the reproductive success of the species. In parallel to these measures, community awareness programmes have also been proposed (2).
For more on this species see:
New South Wales National Parks and Wildlife Service – Threatened Species Information- Green and golden bell frog:
Authenticated (25/05/05) by Frank Lemckert and Traecey Brassil of Forest Resources Research, New South Wales, Australia.
- Larvae: stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
- Metamorphosis: an abrupt physical change from the larval to the adult form.
IUCN Red List (March, 2004)
New South Wales National Parks and Wildlife Service – Threatened Species Information- Green and golden bell frog (March, 2004)
Amphibia Web (July, 2010)
Victorian Flora and Fauna Guarantee Act (May, 2005)
National parks association of New South Wales -Wandering wildlife (March, 2004)
Wildlife of Sydney (March, 2004)
- Lemckert, F. (2005) Pers. comm.