If you live in Sydney and have a garden pond in the backyard it is highly likely that you may hear a repeating ‘tock’ noise before going to bed every night. The noise you are hearing is the mating call of a male Striped Marsh Frog (Limnodynastes peronii). This frog species is adapted to marsh environments, with no flowing water (hence why the genus name ‘Limnodynastes‘ translates to ‘lord of the marsh’). The morphology of this frog is peculiar compared to other frogs. Almost every frog in Australia (or the world for that matter), have larger females than males. This frog species has larger males. Distinguishing whether a Striped Marsh Frog is a male or a female is quite easy: males have a buff upper body, as if they have been hitting the gym (see the picture below), as well as a nuptial spike (a body protrusion on the inside of the front hands). The nuptial spikes are for gripping onto females during amplexus (mating). Females lack the buff looking upper body and also lack a nuptial spike.
Usually the loudest frog wins the females, as the loudest frog is usually the biggest frog. Some frogs will find a spot which echoes more (such as in a drain pipe) to trick the females into thinking they are larger. When there is multiple males calling in the same spot, ritual combat can occur. Striped Marsh Frogs have ritual combat which involved puffing themselves up and wrestling, trying to drag the other underwater. This may go on for a while. The winner is determined by stamina i.e. who can keep going the longest.
They are known to be very opportunistic breeders and may breed all year round. Their eggs are incredibly easy to identify; they are a floating mass of bubbles with little dots in them (each is an embryo which has the potential to become a frog). In each egg mass, there may be over 2000 embryos, but on average there will be around 800.
The tadpoles of this species can get quite large and are generally black, with a dark brown coloured belly. Tadpoles can take from 7 month – 12 months to metamorphasis and eat algae, detritus and will readily take meat (e.g. drowned slug, injured tadpoles), even small tadpole must be weary of being eaten by larger ones. After metamorphasis, juveniles will hop away and forage in the garden, mainly eating small invertebrates. As a rule of thumb, Striped Marsh Frogs will generally eat anything that fits in their mouth, including juvenile Striped Marsh Frogs. I have seen this frog species make good use of Christmas beetles during the warmer months.
Hopefully you now know a little more about the interesting lives of this common garden frog. Amazing things such as male ritual combat, romance and insect hunting may be occurring in your garden right now. You don’t know if you don’t look.
I implore all of you to pay more attention to your garden and you may see something remarkable. Better still, get a pond. The frogs would appreciate it.
Comment below if you have marsh frogs in the backyard or if you have seen something amazing in your backyard.
Thank you for reading