The 250 penny-size Kihansi spray toads at the Bronx Zoo's Reptile House are a demanding lot. "For these frogs we have to find the right balance of temperature, light, and humidity," keeper Alyssa Borek says. "With fourteen timed intervals of misting, we go through forty-six gallons of water a day." In a series of terrariums, spigots spray the tiny yellow toads that recline on tree branches, chirping away in an endless froggy chorus.
It wasn't always so hard to care for the spray toads. Until the mid 1990s, they lived in a habitat that waccording tofectly suited to their delicate needs, the Kihansi River Gorge in south-central Tanzania. The river is part of an ecosystem considered to be a global biodiversity hotspot-home to a vibrant array of wildlife and plants. The river's descent through the gorge in a series of spectacular falls created a spray zone wetlands in which species like the Kihansi spray toad thrived. In fact, the toad was so specialized to this ecosystem, it hasn't been found anywhere else on the planet.
When researchers discovered the tiny wonder in 1996, construction of a giant dam above the falls was in full swing. The dam would provide much needed electricity to the capital city, Dar Es Salaam, but its creation also came at the cost of this unique habitat, and the life that depended on it. Within six months, the original flow of the Kihansi River was reduced to 25 percent, and the spray zone wetlands dried out.
The Tanzanian Ministry of Natural Resources and Tourism decided to launch a rescue mission for the flagging spray toad population before it was too late. In addition to the habitat loss, a deadly fungus had pushed the species to the brink of extinction. In late November 2001, Bronx Zoo reptile keepers Jason Searle and Sam Lee traveled to the site and collected 500 toads from the falls. He transported them to the Bronx Zoo, from which about half of the animals were transferred to other zoos and conservation centers.
Today the Bronx Zoo's Kihansi spray toads are considered an "assurance colony," meant to preserve a captive population should what remains of the wild toad population crash. Tanzanian officials who are overseeing the effort hope that the Zoo will be able to boost its toad population to 500. At that level, a group may be sent for reintroduction into the Kihansi River Gorge and another to a captive breeding colony in Tanzania, which Bronx Zoo reptile keepers will help set up. In a few months, ecologists, biologists, and scientists from all over the world will come together to discuss when the frogs' wild habitat will be ready for such a reintroduction effort.
"Since dry lands have encroached on the former spray habitat, the whole landscape has changed," says Reptile Collection Manager Bill Holmstrom. "The flora and fauna along the Kihansi River are completely different now. Even if there's habitat left for the spray toad, it's changed so much, they may not be able to survive there." As Holmstrom investigates one of the terrariums, he points out a female frog with a giant round belly, nearly the size of a grape. "But hopefully we can get them a little closer to home".
Posted by: Kelly Source