Bool lagoon in South Australia’s South East bustles with life. Thousands of waterbirds were floating, flying, or walking through the water. Magpie Geese were honking away in the vast swathes of Water-ribbons, while Whiskered Terns scouted the narrow water-filled channels looking for a tasty tadpole meal. Fairy-wrens and Southern Emu-wrens sung from dense vegetation at the water’s edge and Lowland Copperhead snakes slid off the warm roads to make way for cars. Bool Lagoon Game Reserve is about 360 km south east of Adelaide and is a large freshwater lagoon system that provides a refuge for diverse fauna including many rare and vulnerable species of birds, fish, reptiles and amphibians. I have rarely seen such an abundance of wildlife in one place and it is awe-inspiring.
As day turns to night and the Magpie Geese honk less often, a different cohort of animals become active. Fluttering about in the half-light, silhouetted against the evening sky, small bats emerge and begin catching insects. High pitched chirps appear from every direction from what could be Lesser Long-eared bats or Chocolate Wattled Bats. As I am getting nestled down in my sleeping bag I hear a plonk on the side of the swag. Moments later another plonk! I unzip my swag and grab my torch to investigate. Illuminated in the torchlight is a large green frog, a Southern Bell Frog. A short walk around camp reveals many more of these spectacular amphibians making their way through the night.
Southern Bell Frogs, also called Growling Grass Frogs, are fairly large frogs reaching about 11 cm long. They have green bodies with brown markings and golden stripes on the upper edge of the flanks with a green stripe running from their head down their back. They are quite variable with some individuals being darker green and more brown while others have very little brown and are light green. The bell frogs are nocturnal ambush predators and sit and wait for their prey to stroll within striking distance. Unfortunate souls may be beetles, insect larvae, bugs, termites and sometimes small frogs including others of their own species.
Southern Bell Frogs were once common throughout south-eastern Australia however they have declined considerably in recent years and are now listed as vulnerable nationally. This has been linked to a number of potential factors including habitat fragmentation and degradation, barriers to movement, disease, pollution, as well as other influences which have led to the loss of some populations and the isolation of others.
Southern Bell Frogs occur in areas with permanent or near permanent water such as lagoons, lakes, slow flowing creeks, dams, channels and rice crops. Permanent water, or close to it, is important because the frogs breed during spring and summer and it enables the eggs and tadpoles to develop fully without the risk of the water drying up. The adults can be found in thick vegetation in or near the water’s edge, or in ground debris and soil cracks. They are however sometimes found a considerable distance from the water.
Bell frogs are wonderful, charismatic animals with beautiful and variable colours and are definitely an amphibian to keep an eye out for. Bool lagoon is a stronghold for the Southern Bell Frog in South Australia and is worth a visit not only for the frogs but also for the vast array of other fascinating creatures that live at and use the lagoon system as a refuge.