Yellow toad births offer hope for extinct-in-the-wild species
Yellow toad births offer hope for extinct-in-the-wild species
Rhett A. Butler, mongabay.com
September 4, 2008
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The birth of Kihansi spray toadlets at the Wildlife Conservation Society’s Bronx Zoo has renewed hopes that the species can someday be successfully reintroduced to its natural habitat in a remote gorge in Tanzania.
The Kihansi spray toad is believed to have been driven to extinction by the destruction of its only known habitat — the Kihansi gorge in the Southern Udzungwa Mountains of South Central Tanzania — by a hydroelectric project. Its demise was hastened by the appearance of the deadly chytrid fungus, a pathogen that is taking a heavy toll on amphibians around the world. The last confirmed sighting of the species in the wild was in May 2005.
  This one week old Kihansi spray toadlet image provides a rare look at a “baby” of its species. The red paperclip (one of the smaller types) illustrates just how tiny this amphibian really is. Photos by Julie Larsen Maher © WCS   Adult Kihansi spray toads (mating in the lower image) at the Bronx Zoo. Photos by Rhett A. Butler. |
Anticipating the impact of the dam, conservationists worked with the Tanzanian government to establish a captive breeding program for the species, but the program was initially fraught with difficulties associated with a particularly fragile species, including disease. By the spring of 2004, the worldwide captive population of the Kihansi spray toad was down to 70.
Since then the outlook for the species has been improving. A captive breeding program by the Bronx Zoo has brought the facility’s population up to 300 toads, including the dozen born last week (unlike most other amphibians, spray toads have live birth, rather than laying eggs). Kihansi spray toads are now also breeding successfully elsewhere.
WCS says it plans to work with Tanzania to return some of the captive toads to their habitat where a sprinkler system has been installed to counter the ecosystem changes caused by the hydroelectric dam. Reintroduction will require complete eradication of the chytrid fungus from the gorge.
Still while it looks increasingly likely that the Kihansi spray toad has escaped its brush with extinction, amphibians are still in big trouble worldwide. According to the recent Global Amphibian Assessment, about a third of amphibians are threatened with extinction. Pollution, the introduction of alien species, habitat destruction, over-collection, climate change, and the emergence of the pathogenic chytrid fungus have driven more than 170 species to extinction over the past two decades.
In an effort to save the most at-risk species, last year saw the launch of the Amphibian Ark, an initiative by zoos, aquariums, and botanical gardens to establish captive populations for 500 species.
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