Monday, 21 December 2015

Frogs and Toads!

Cane toad (Rhinella marinus) - an introduced species and environmental pest
Do you know the difference between a cane toad's eggs and frog's eggs? And why does this matter?

With the massive public awareness campaigns, I assumed most Australians knew about the cane toad and what do do about it - so why am I writing this post? 

Yesterday, I was completely surprised.  In an entire room of gardeners, at a permaculture talk I was giving, not one person knew how to distinguish between frog and toad eggs.  I think for a moment I was speechless. I know I should never assume (I can hear my father's advice clearly in this comment!). But obviously the cane toad public campaign has faded into distant memories and newcomers to these cane toad areas of Australia have not been exposed to this information.

Often in the early evening, I am out in my garden harvesting the last garnishes and leafy greens for dinner, I stumble across many big cane toads sitting up tall. Sometimes I accidentally step on them!  They are everywhere.

When I arrived in Queensland in 1993, I got to know this tough warty creature. I learnt that how they are a big problem for wildlife - outcompeting and poisoning local species, contaminating water and eating insects - including bees, reptiles and even small birds and mammals. They can also be harmful to pets and people.

Sixty years ago, the Queensland Government introduced the cane toad (Rhinella marinus) to control cane beetles, but the experiment failed and the toads have been slowing marching across Australia since. It was all a big mistake that we are still trying to sort out.

Public campaigns encouraged everybody to help slow their spread. Back in the mid 1990s, I was astonished by the neighbourhood cane toad hunts in Brisbane. I had just arrived from Melbourne to find kids racing around with sticks and bins in the early evening collecting as many toads as they could in what seemed like quite a violent frenzy. If I remember well, some communities even offered prizes for the biggest haul.

It was all a bit too gruesome for me. I did however become a vigilant pond watcher and have dutifully scooped many thousands of cane toad eggs from ponds.  It seemed by far the most humane way that didn't involve killing the toad or collecting and freezing them.

So here it is - the simple way to tell the difference between frog and cane toad eggs....

Cane toad eggs are long strings of black pearls. Frog eggs are in clusters usually looking a bit like detergent bubbles with little black spots. If you find the cane toads, scoop them out and leave them in the sun to dry out.

Cane toad eggs - longs strings of black pearls 
Image Source:
Spotted Marsh Frog and eggs
Image source: © Craig Cleeland
Strangely, cane toads are not actually a declared pest in Queensland but we do need to remember that even though we are encouraged to eradicate them, that they are animals and can suffer pain.  In fact, the Queensland Animal Care and Protection Act, 2001, makes it unlawful for us to be cruel to cane toads, and the RSPCA has developed an information sheet on how to humanely despose of adult can toads.


  1. Hi Morag, a guy who was at a gardening talk explained to me that cane toads have to have at least 11 inches of water depth to breed but can't jump higher than 23 inches, so if you have shallower ponds etc.than the breeding depth they can't breed and if you have water pots deeper than jump height they can't use that either.
    I hope I have remembered the figures correctly, it was a few years ago and the guy said he belonged to a Brisbane frog breeders group, their ponds were 8 inches deep, this might be handy information to pass along when you are discussing toads and I am sure converting to centimeters would be more relevant to younger people.

    1. Merry Christmas Margaret. Thanks for sharing that information.

  2. I believe Cane farmers view the toads a bit differently than the rest of us. I was told by one that before cane toads the cane beetles were so thick that in one incident a young girl went out to give her father a lantern one night and she was smothered by the beetles and died. They are not so thick anymore but that may be the sprays rather then the toads. But at the time it made a huge difference.

  3. people also need to know that not everything brown is a toad, frogs come in colours other than green. I have 3 ponds and the frogs at night are deafening don't hear very many toads here which I like.

    1. Good point Judi, absolutely. You can see lovely little brown striped marsh frog above in the photo above. A good way to tell the difference is the way they stand. Toads in resting position seem to be sitting up tall whereas frogs sit low and flat.

  4. Thanks or your comment Trace. That's a tragic story about the girl. I think you may be right - it's probably more to do with the sprays than the toad. I understood that the beetles were a severe problem which is why the toads were introduced, but unlike their impact in Hawaii and the Carribbean Islands, the box of toads shipped to Gordonvale, just south of Cairns, did not impact the beetle - they could not jump high enough to where they lived on the cane. Also, at the time of year when the beetle's larvae were hatching from the ground, no toads were about. My understanding is that the cane toad had no impact on the cane beetles at all and farmers had to go back to the use of chemicals to kill the beetle. I would be really interested to hear if there were stories of success.