Scattered around Sutherland Shire are small disused quarries. These sites echo with age from a hundred or more years ago when the generations before us were mining out shale and sandstone to build some of the very buildings we use today. During this mining extraction process, holes the the ground were created, cutting into the bed rock. The sandstone bed rock is impermeable and more often than not, these old mining spots become full of water as the mining works usually cut in a pond like shape into the earth.
As an indirect and unforeseen consequence, these disused quarries have become perfect habitat for frogs. Some of them being large enough to sustain permanent wetlands and other smaller ones become equally as important ephemeral wetlands (A water body which dries up periodically). In fact, in this day and age, ephemeral water bodies may be especially important for frogs, as their periodic drying removes the water born fungal pathogen effecting frogs world wide called ‘chytrid’.
It’s not just frogs that are able to utilize these quarry wetlands. Water birds, snakes and freshwater macroinvertebrates are able to live and breed in these habitats. A good example of these habitats are the many sand mining quarries found along the stretch of Greenhills near Cronulla, which reach out patchily to Kurnell. There are many smaller disused quarries found scattered throughout the Royal National Park.
A few nights ago, I went to investigate how much diversity of frogs one of these artificially created wetlands harbor and I was astounded and very impressed to hear and see at least 9 species.
The first noise I heard as I approached the wetland was clicking of the Common Eastern Froglet (Crinia signifera) which you are likely to hear almost all year round in any pool of water, whether its a puddle or a wetland. The next noise I heard was unfamiliar to me at first. It sounded reminiscent of a ducks ‘quack’ but It sounded frog like to me. I followed my ears to locate one and It turned up being the Wallum Rocket Frog (Litoria freycineti). It was exciting to hear them calling in such numbers (around 20 at least) as they usually begin calling in November, so a few weeks early.
I did note that the water in this particular wetland was very warm and could be an explanation for the early arrival of the Wallum Rocket Frog. It could also explain the abundance of metamorphling frogs literally jumping every where. From tiny 5 mm Common Eastern Froglet metamorph, to larger Striped Marsh Frog metamorphs. In warm water the growth and development of the tadpole is spend up which is an adaptation to avoid being stuck in a water body that is destined to dry up.
The next noise that became apparent to me (which were also in very high abundance, approximately 30+ calling individuals), were the Smooth Toadlets (Uperoleia laevigata). These small frogs make a dull ‘arrrkkk’ sound, calling terrestrially, sometimes quite a distance from the water.
After listening carefully I started to tune into the frequencies of some tree frog species who were joining in on the chorus. Calling in much less abundances, the Perons Tree Frogs (Litoria peronii) maniacal cackle could be heard in numbers between 5-10, and also the occasional inclusion of Eastern Sedge Frogs (Litoria fallax), with about 5 individuals contributing.
I noticed huge amounts of tadpoles in the water. On closer inspection I could see multiple different species and the occasional dragonfly nymph (a common predator of tadpoles). However it seemed they were the only predator, with no appearances of fish. Perhaps this is a reason why tadpoles are in such high abundances here. I managed to scoop a large tadpole out which I thought could of been a Giant Burrowing Frog (Heleioporus australiacus) tadpole. However it was more likely to be a Striped Marsh Frog (Limnodynastes peronii) tadpole… Speaking of which where are the Striped Marsh Frogs?
After scanning deciding to head home I did a quick scan of the bank as I was exiting and stumbled across a frog I’m sure you are all familiar with, the Striped Marsh Frog (Limnodynastes peronii). How strange it was to hear not even one calling, and only see 2 this night. Perhaps they don’t fair as well in natural sites, and utilize urban areas better?
We have covered a frog fact Friday on this common frog and can read more about it here: http://gumnutnaturalist.com/frog-fact-friday-the-most-common-frog-of-sydney/
After getting ready to head back to the car, I stopped to have one last marvel at the chorus of multiple species of male frogs competing to find a mate. I took recordingg to share it with you. See if you can tease out which species of frogs are calling in the recording!