Illawarra frogs

Frogs are amphibians and separated from other groups of animals as they have a moist skin that absorbs water and oxygen and are cold blooded. Amphibians have double lives in that most lay eggs in water where the young live and breathe with the aid of gills, until they metamorphose into frogs, which live on land. Many people like frogs and they have become symbolic of green products. Apart from the Green and Golden Bell Frog most other species are nocturnal. The Illawarra had some 24 species the majority of which are tree frogs that have suction caps on their fingers and toes to help them climb. I say ‘had’ as Stuttering Frog is now locally extinct.

The Leaf Green Tree Frog, a local frog species that breeds in streams and creeks. Image by Garry Daly ©.

Frogs of the Illawarra

Note: Those shown with * are listed on the NSW Biodiversity Conservation Act (2016)

Family	Species	Common name
Hylidae	Litoria aurea	Green and Golden Bell Frog*
	Litoria caerulea	Green Tree Frog
	Litoria citropa	Blue Mountains Tree Frog
	Litoria dentata	Bleating Tree Frog
	Litoria fallax	Dwarf Tree Frog
	Litoria freycineti	Freycinet's Frog
	Litoria jervisiensis	Jervis Bay Tree Frog
	Litoria lesueuri	Lesueur’s Frog
	Litoria littlejohni	Littlejohn's Tree Frog*
	Litoria peronii	Peron's Tree Frog
	Litoria nudidigitus	Leaf Green Tree Frog
	Litoria tyleri	Tyler's Tree Frog
	Litoria verreauxii	Verreaux's Tree Frog
Limnodynastidae	Heleioporus australiacus	Giant Burrowing Frog*
	Limnodynastes dumerilii	Pobblebonk
	Limnodynastes peronii	Striped Marsh Frog
	Mixophyes balbus	Stuttering Frog*
	Mixophyes fasciolatus	Great Barred Frog
Myobatrachidae	Crinia signifera	Common Froglet
	Paracrinia haswelli	Haswell's Toadlet
	Pseudophryne australis	Red-crowned Toadlet
	Pseudophryne bibronii	Bibron's Toadlet
	Uperoleia laevigata	Smooth Toadlet
	Uperoleia tyleri	Tyler's Toadlet

Urban frogs

The Striped Marsh Frog copes with urban life as it can breed in small shaded ponds. This species makes a repeated “bock bock” call that may keep people awake at night. Females lay eggs in a foam mass and this is the characteristic spawn that east coast Australians usually identify with frogs, although most species lay eggs under the water in clusters. The Striped Marsh Frog has a retiring disposition hiding in dense vegetation or under logs or rocks. The opposite side to this behaviour is that the males fight to secure prime locations from which to call. They have a spine in their thumbs that can be used to scratch and even kill their opponents. Their tadpoles are quite remarkable as within a spawn there are fast and slow growing individuals. This gives the species an advantage as the survivors of one spawn can emerge as frogs between 3 and 12 months after the eggs have hatched and enter the terrestrial world over a range of weather conditions. Tadpoles eat detritus and protein such as meat and frogs’ eggs. The Striped Marsh Frog tadpoles are cannibalistic but also eat the eggs of other species of frog. So if you have a shaded pond that is colonised by the Striped Marsh Frog then there is little chance of any other species making your pond home.

So what do you do if you want to encourage a range of frogs to your place? Here are some tips: ponds with fish generally do not support frogs as fish eat tadpoles (years ago people used to think the small exotic aquarium fish the Mountain Clouds did not eat taddies but they do). Large shallow ponds that receive direct sun are better than small deep ones in the shade. Ponds that dry out are usually better than ones that have water all year round. So emptying a pond mid winter can be a useful strategy to promote diversity. Ponds that have some water plants provide locations for frogs to attach eggs, purify the water and also are features. If your pond has all these features then you might get tree frogs calling and breeding there. Some species that use garden ponds are Peron’s Tree Frog, Dwarf Tree Frog and Verreaux’s Tree Frog. The first species has a loud jack-hammer like call that may irritate some people.

Peron's Tree Frog is easily identified by the blackish cross shape in its eyes. Image by Garry Daly ©.

Verreaux's Tree Frog breeds in shallow dams and ponds in winter and attaches its eggs to submerged twigs. Image by Garry Daly ©.

I know a fellow at Port Kembla who loves Green and Golden Bell Frogs. One time he did not attend to his in-ground pool and this endangered species colonised the place. He was thrilled but not so his family who were banned from swimming in the pool. It was incredible to visit the guy and see a number of Bell frogs calling and mating during the day in this algae filled pool. The Bell Frogs used the pool for years but disappeared and the owner had no idea why. When I visited his place I found the pool was colonised by the yabbie Cherax destructor, a species normally found west of the dividing range. The crustaceans had colonised his pool from his neighbours’ fish pond. The pool had to be drained and the crayfish removed. However, since that time the frogs have rarely been back to his pool to breed.

Of course frogs need somewhere to hide so there is a need to provide this habitat as well. Native emergent species such as Water Plantain (Alisma plantago-aquatica) and or Yellow Marsh-flower (Liparophyllum exaltatum) are what is needed for metamorphling tree frogs to use as basking sites when they first leave the water. Species such as Peron’s Tree Frog and the Dwarf Tree Frog loaf on the large leaves away from predators such as Eastern Water Skinks for the first few days when they leave the water. Spiny-headed Mat-rush is also good at providing a place with dense foliage and high humidity for small species such as the Dwarf Tree Frog. This species is used as an overwintering site for adult Dwarf Tree Frog.

Dwarf Tree Frogs on a water plant. Image by Garry Daly ©.

Other habitat that may be provided includes piles of rock and old timber. Tree frogs such as the Bleating Tree Frog and Peron’s Tree Frog live in hollow trees so this type of habitat is difficult to replicate. However, if a large hollow exists in a place nearby the frogs may overwinter there and return to your place to breed.

Rural frogs

In a rural landscape there are lots more opportunities to conserve and create frog habitat so it is best to describe the natural habitats where frogs breed to get an idea of where these animals hang out. Certain species breed in creeks but not dams. So having a natural creek is an asset for frog biodiversity. If a place lacks this feature then a whole lot of species will be absent. The stream-breeding species in the Illawarra include the Blue Mountains Tree Frog, Lesueur’s Frog, Leaf Green Tree Frog, Stuttering Frog, Littlejohn's Tree Frog and probably the subspecies of Pobblebonk Limnodynastes dumerilii dumerilii. Then there are Giant Burrowing Frog, Freycinet's Frog and the Red-crowned Toadlet, which breed in the smallest bodies of moving water but their tadpoles end up in pools either in or beside creeks. Of the stream-breeding specialists species the Blue Mountains Tree Frog, Lesueur’s Frog, Freycinet's Frog, Littlejohn's Tree Frog, Red-crowned Toadlet and Pobblebonk Limnodynastes dumerilii dumerilii occur primarily in areas with sandstone-based creekbeds. These species can be found in places like Darkes Forest outside the scope of this study area but the Blue Mountains Tree Frog does occur along the coast at Stanwell Creek. Unfortunately the Stuttering Frog is locally extinct having succumbed to the deadly chytrid fungus that was introduced to Australia, probably from Africa, in about 1980.

Lesueur's Frog, showing the bright yellow colour of the male during the breeding season. Image by Garry Daly ©.

The Red-crowned Toadlet is a striking-looking species, with a preference for sandstone soils. Image by Garry Daly ©.

Then there are species of frog that mostly breed in dams or bodies of still water such as coastal wetlands. They include the Green Tree Frog, Green and Golden Bell Frog, Bleating Tree Frog, Jervis Bay Tree Frog, Tyler's Tree Frog, Verreaux's Tree Frog, Brown-striped Frog, Smooth Toadlet and Tyler's Toadlet. The Green Tree Frog is now rare in the area and is probably locally extinct from Bulli to Stanwell Park but still persists on the coastal plain around Toolijooa, especially where large old Swamp Oaks persist near areas that become flooded after heavy summer rain. Similarly the Green and Golden Bell Frog is now rare in the area because of chytrid fungus and because many coastal wetlands have been drained and filled. I suggest that in places like Port Kembla the copper from the old smelter ameliorated chytrid and as this leaches from the environment the population of Bell Frogs are exposed to lethal levels of chytrid.

Creating or recreating a large shallow expanse of water is an asset for frogs. In one area (Tapitallee, just outside the scope of this study area) we convinced new landowners on rural properties to fill in drainage channels that were dug to drain ephemeral wetlands. This sort of action is rare but if landowners and councils are educated on the benefits of having temporary ponds then the rush to fill may be curbed.

Creating dams is generally a good action for frogs but a word of warning. Bibron's Toadlet has been severely impacted by clearing the bush and creating dams. This species (like its cousin the Red-crowned Toadlet) breeds in the upper laterals of small creeks. The males make tunnels in the moss or under the leaves in places where water seeps through the mulch. They call from these concealed locations and if lucky get a mate. The males stay with the eggs until they hatch, which is usually in late summer or autumn when rain floods the site. The taddies swim into small pools where they complete their aquatic life. Constructing a dam over the headwaters of a gully can compromise the specific breeding requirements of this frog as the large area of seeping water is replaced with a body of open water that is not suitable for this species.

Frogs can be found in surprising places. These Bleating Tree Frogs are clustered in a piece of pipe. Image by Garry Daly ©.

Useful plants to attract frogs

Common name	Scientific name	Species	Use
Water Plantain	Alisma plantago-aquatica	Dwarf Tree Frog, Baby Peron’s Tree Frog	Perch
Swamp Lilly	Crinum pedunculatum	Baby Peron’s Tree Frog	Refuge
Gymea Lilly	Doryanthes excelsa	Peron’s Tree Frog	Refuge
Tall Spike-rush	Eleocharis sphacelata	Green and Golden Bell Frog, Dwarf Tree Frog, Jervis Bay Tree Frog	Refuge
Red-fruit Saw-sedge	Gahnia sieberana	Dwarf Tree Frog	Refuge
Spiny-headed Matt-rush	Lomandra longifolia	Dwarf Tree Frog	Refuge in winter
Frogsmouth	Philydrum lanuginosum	Baby Peron’s Tree Frog, Bleating Tree Frog	Refuge
Cumbungi (Bullrush)	Typha spp.	Green and Golden Bell Frog	Refuge