By Les Minter
Late afternoon on the Gamkaberg, with the ground still wet from yesterday’s rain. Shadows begin to reveal the work of water and time on the mountains to the south.
It’s a beautiful sight, but I only have eyes for the small, plump frog I am holding in my hand. We have been turning rocks all day, searching for the Gamkaberg Rain Frog and, at last, here it is!
Breviceps (hereafter affectionately referred to as brevies) are not your common-or-garden frog or toad: they ooze character.
When meeting a brevi for the first time, people are immediately charmed by their human-like faces and grumpy expressions. Furthermore, whereas most frogs leap about wildly when meeting humans (who, in turn, are inclined to leap about too), brevies waddle along as though they had all the time in the world to get from A to B.
Amphibians, typically, live a double life: first in water, as tadpoles, and then on land, as adults. Brevies have broken this rule, living entirely on land. They spend most of their time buried in the soil, only coming to the surface after rain to feed on ants, termites and other small invertebrates, and to mate.
Eggs are laid in an underground chamber constructed by the female, and the developing tadpoles obtain all their nutrients for growth and metamorphosis from the egg yolk. Whereas free-living tadpoles in ponds and streams have gills for breathing, and rasping mouthparts for feeding on plant material, brevie tadpoles lack these structures, absorbing oxygen through their skin.
Mating frogs adopt a position known as amplexus, in which the male approaches the female from behind, clasping her tightly under her arms or around her waist, to ensure that he is in the right position to fertilise her eggs. Male brevies have short arms and are smaller than the females, making it difficult for them to remain in amplexus while the female burrows into the soil to construct the egg chamber.
This problem has been solved (through natural selection acting on skin secretions) by the evolution of a strong glue that ensures the male “sticks around” until his services are no longer required. After a few days the glue weakens and the pair separate, the female remaining with the developing tadpoles until metamorphosis is complete.
About 20 brevi species are recognised at present, and most are endemic to South Africa, with only a few occurring further north. The Gamkaberg brevies are isolated from those living on the Langeberge and may have diverged genetically to the extent that they represent a new species. Further research is needed to answer this question.
At a time when the human population recently reached 8 billion (from 2.5 billion when I was born) and we are rapidly and unsustainably squandering our natural resources, I am tempted to ask: “Do we really want to know? “
In A Short History of Progress, Ronald Wright ominously predicts that “this new century will not grow very old before we enter an age of chaos and collapse that will dwarf all the dark ages in our past”, and comedian George Carlin amusingly points out how arrogant it is to talk about “Saving the Planet” when we can’t even take care of each other.
CapeNature’s website for Gamkaberg Nature Reserve informs us that “its name is derived from the Khoisan, gami, meaning lion, where the Cape Lion – now extinct – once so successfully wondered (sic) here.”
And then, just in case you were wondering how the Cape Lion became extinct, it adds: “As the humans approached, so the lions withdrew so humanity could prosper”. So that’s what those (apparently unsuccessful) lions were wondering as they wandered over the Gamkaberg – whether-or-not they should withdraw so humanity could prosper?
I draw some comfort from the thought that before the Bloubok, before the Cape Lion, before the VOC, even before the KhoiKhoi and San, brevies lived on this hill …. and will probably still be there after we are gone.
*Les Minter is a retired herpetologist and is therefore someone with friends in low places.