Cape Dwarf Mountain Toad Survey

Cape Dwarf Mountain Toad Survey - Southern Africa : An elusive amphibian: the silent tails of the Cape Dwarf Mountain Toad You’ve probably already heard the news: amphibians are in trouble all over the world. Familiar to all of us, from the omnipresent click-click-clickety-click of the Clicking Stream F

An elusive amphibian: the silent tails of the Cape Dwarf Mountain Toad

You’ve probably already heard the news: amphibians are in trouble all over the world. Familiar to all of us, from the omnipresent click-click-clickety-click of the Clicking Stream Frogs around our homes to the light chirp of the Moss Frogs which tell us that we’re about to find a wet patch in the fynbos, frogs are everywhere. They rely on both ample supplies of freshwater and land to complete their biphasic (two phases) life cycles: that makes them susceptible to changes in either medium.
Cape Town is well endowed with frogs, and while we’ve all heard of the Table Mountain Ghost Frog (found on Table Mountain and nowhere else) and the Western Leopard Toad (found on the Peninsula and selected areas toward Gansbaai), how many of you have heard of the Cape Dwarf Mountain Toad Capensibufo rosei?

If you study frogs, you can be assured that at least once a year they’ll let you know exactly where they are by calling in species-specific voices to attract a mate. Large choruses of frogs can drive local residents to sleepless nights, but at least for those who live next to Western Leopard Toad breeding sites they are only active for a few nights each winter. Then you’ll hear a gentle snoring, rocking too and fro between males from different places in the pond.
But did you know that there are frogs that don’t call? The Cape Dwarf Mountain Toad is one such silent species: this makes finding a frog that is only 24mm long (at its largest) very difficult. This species occurs in our beloved Cape Fold Mountains: Hottentots-Holland, DuToitsberg/Limietberg, Riviersonderend and Klein River, as well as the Peninsula. Not a very big distribution, and very fragmented – which is why the IUCN saw fit to give this species a threatened status: Vulnerable.

On the Peninsula, populations have been recorded in Cape Point, Silvermine, Chapmans Peak, Blackhill Road and Table Mountain. Together with Dr. Krystal Tolley (and the permission of TMNP) I’ve been monitoring the population in Silvermine for the last three years. They really are quite fascinating animals with large assemblages of breeding adults in late August, strings of amber-beaded eggs in early September and the most torpedo shaped tadpoles that you’re ever likely to see throughout September. By October, most of them have metamorphosed into tiny adults and are off into the fynbos to live their enigmatic lives until its time to breed again.

We need to know more about the other populations on the Peninsula. Our aim is two-fold:
• First to consider how they are doing in this area in the run up to another IUCN red-list assessment, and
• second to undertake a genetic study to find out how well they move between populations – or even if they move at all.
We have visited all the sites where they’ve been recorded. The most eerie news is that we haven’t found them anywhere except Silvermine and Cape Point. But then neither has anyone else back to the 1970’s in some places and the 1920’s in others.

Is it time to be worried about our Cape Dwarf Mountain Toad? I’m usually optimistic, but the last time these frogs were seen on Table Mountain was 1974. Despite many searches in the 1990s and more recently in the past 3 years, not a single individual has been found. This suggests that if this species does still occur on Table Mountain, the numbers are now very low, which in itself is worrying. I know that you are out and about on the mountains all the time, and it would be fantastic if you’d note down if you ever see these frogs.
I’m not asking you to pick them up or bring them home, in fact it’s best if you don’t touch them at all! But iSpot is a fantastic opportunity to obtain this much needed information and a location (preferably with GPS) would be fantastic. It doesn’t have to be just on the Peninsula: anywhere that you see these wonderful Cape Dwarf Mountain Toads would help add data to make our assessment more accurate.

John Measey

See what they look like : Capensibufo rosei

11 Oct 2011
Tony Rebelo