A bullfrog expert is calling for the urgent creation of a conservancy to protect Gauteng's only breeding population of enigmatic giant bullfrogs, in Midrand.
This follows the deaths of thousands of juvenile giant bullfrogs after the Johannesburg Roads Agency (JRA) graded a road at Midrand's protected Glen Austin Pan.
It's the latest threat to the survival of the world-famous giant bullfrogs, hemmed in by development; squashed by quadbikes, traffic and illegal dumping; or snatched for the exotic-pet trade.
Bullfrog specialist Clayton Cook, who has monitored Glen Austin's bullfrogs since 1991, termed the graded road "non-negotiable" and demanded that it be closed in order to protect them.
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The rare species spend most of the year dormant, encased in an underground cocoon, surfacing from their retreat only briefly to feed and breed.
And with around 1 000 breeding adults at Glen Austin - the only viable breeding population left in the most "critical wetland habitat in Gauteng" - their survival is of "international importance".
Two weeks ago the JRA graded the gravel road alongside the pan. Until now, only Laurie Kay, a pilot whose smallholding overlooks the pan, has had access to the gravel road that ends at his driveway.
"There were concrete barriers for the last 15 years that restricted access to Kay," explained Cook.
"Last Saturday, he discovered three-ton trucks, bulldozers and graders opening up the entire road.
"It's the worst time of the year for this to happen. Thousands of juvenile bullfrogs are migrating from the pan."
The summer had seen an "incredible" bullfrog breeding season, with three successive breeding events in the pan.
"On the Sunday, I saw dead bullfrogs on Belvedere Road. We can't say exactly how many were destroyed."
Their migration from the pan is influenced by their growth and temperature, Cook pointed out.
"They bury themselves in the top 5cm to 10cm of the softer sandy soils on the road. We know that about 30 tons of sandy soil has been removed from that site [by the JRA]. The grader decapitates and squashes frogs, toads and snakes - whatever is buried in the soil."
Kay said he saw thousands of the migrating bullfrogs dug up by front-end loaders and then run over by them.
"The day before, my wife and I saw thousands of little froggies crossing the road. Since they've graded, I've only seen two juveniles. It's sad."
Cook is adamant: "The area should be registered as a private conservancy. Residents must be encouraged to leave natural grassland in their gardens for the frogs to migrate through, use palisade fencing and not use gardens forks that dig up the dormant frogs in their gardens."
JRA spokesperson Conel Mackay said the grading was requested by residents.
- This article was originally published on page 9 of The Star on March 29, 2008
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