Feature Story

The Kihansi Spray Toad’s Journey Back Home

June 10, 2015

When we look back at the lessons learned from our decades-long work in biodiversity conservation, the Kihansi Catchment Conservation and Management Project (KCCMP) and its central character, the tiny Kihansi Spray Toad, stand out as an unprecendented success story.

The original GEF-funded project aimed to protect the biodiversity of the Kihansi area in the Udzungwa Mountains of Tanzania – part of one of the world’s biodiversity hotspots. A central activity of the project, and a historical accomplishment, is the reintroduction of the Kihansi spray toad, a species that was extinct in the wild, back to the Kihansi Gorge.  Conserving the toad and its habitat has been a long and technically challenging process, involving a wide range of national and international partners.

 

The toad and its habitat become endangered

 

The Kihansi spray toad is a highly specialized species. It has adapted to giving birth to fully formed live young to avoid having eggs washed away by the spray from the powerful waterfalls of the gorge. It has the smallest range of any tetrapod (four legged vertebrate) in the world – restricted to about five acres. A Kihansi spray toad can sit comfortably on a dime and weighs only a few grams. Meanwhile, its young can fit on the head of a pin.

The Kihansi spray toad gets its name from living in the mist zone produced by a single high water fall, upon which it depends to survive. Back in 2000, the opening of hydropower dam upstream seriously affected the flow of water from the Kihansi Gorge Waterfalls, cutting it by 90%. The reduction in the volume of spray, particularly in the dry season, and the subsequent alteration of vegetation composition led the toad’s population to plummet.

In a multi-pronged approach involving partnerships across sectors, the KCCMP project began its work. The GEF-funded project, implemented by the World Bank, took measures to set up an artificial gravity-fed sprinkler system to mimic the natural spray of the Kihansi ecosystem with the remaining water flow.

Unfortunately in 2005, there was an outbreak of the amphibian disease called chyrtid fungus that has devastated amphibian populations around the world. The Kihansi spray toad population crashed from 20,000 to zero, and the species was declared extinct in the wild.

Luckily, before they could completely disappear from the Kihansi Gorge, 499 remaining individuals were moved from the wild to US zoos for captive breeding. Zoo staff had to learn how to raise and successfully grow a population of this toad in captivity, and with hard work, the populations grew and the species was released into its native habitat with the new sprinkler system.

 

The road to conservation

 

In collaboration with the National Environment Management Council (NEMC), the GEF supported a series of activities to re-establish good habitat conditions in the Kihansi Gorge and maintain captive breeding populations, with the goal of eventually re-introducing it into the wild. Among other activities, the project supported the captive breeding of the toad at the Bronx and Toledo Zoos in the US and two captive breeding facilities in Tanzania. It also supported genetic sequencing of the strain of chytrid fungus found in Kihansi, and the ecological monitoring of water quality and quantity in the Kihansi Gorge.

Although keeping the toads alive in captive breeding was challenging due to parasites and population numbers reached a low of 72, the Kihansi spray toad survived. “The story of the Kihansi spray toad’s re-introduction to the gorge is a tremendous and unprecedented success that managed to reconcile energy development in Tanzania, community natural resource management, and conservation of a globally highly threated species”, said Gustavo Fonseca, GEF Director of Programs. Approximately 5,200 individuals have been reintroduced to the wild since October 2012.  Currently, more than 6,200 individuals live in their natural habitat.

“The Kihansi spray toad is an important indicator species for the health of the Kihansi Gorge ecosystem,” said Dr. William Newmark, Conservation Biologist and Research Associate at the Natural History Museum of Utah who has been involved throughout this project. “The reintroduction of an amphibian species back to the wild where chytrid fungus is endemic is a pioneering achievement”. Among other successes of the project, he highlights the rehabilitation of the spray wetland habitat to its original condition, as well as the development of local capacity in Tanzania to manage captive breeding populations. Furthermore, a new curriculum in conservation biology was developed at the University of Dar es Salaam. Biologists working on this project in the area have also found tremendous diversity in the Kihansi Gorge, including a butterfly and a relative of coffee that are found nowhere else on Earth.

The KCCMP project demonstrated the adoption of a collaborative, experimentally-driven, and adaptive approach to conserving the Kihansi spray toad. The third phase of the KCCMP project, worth $5.95 million, extends between 2014 and 2018 and involves the dissemination of knowledge on conservation of the environment to further extend and enhance the conservation of critically endangered species and their habitat in the Kihansi catchment.

 

Looking ahead

 

“The biggest challenge is to establish a long-term sustainable Kihansi spray toad population in the Gorge,” continued Dr. Newmark.  “The best predictor of success for amphibian reintroductions is the number of animals which are reintroduced. Thus, our objective over the next four years is to reintroduce as many toads back to the Gorge as possible.”

Another major challenge is reducing the likelihood of re-introduction of chytrid fungus back to the Gorge. In order to address this, the project will support the construction of new concrete foot baths for sterilizing workers and visitors’ boots at the entrance of each of the spray wetlands. The project is also supporting the development of an Integrated Pest Management Program to reduce pesticide use in the areas upstream and is supporting micro projects that enhance water quantity and quality for people and nature.

Future work to be done also includes maintaining critical gorge infrastructure (spray irrigation systems, walkways and bridge, research station), continuing support for international and national collaboration among scientists and organizations with expertise in amphibian reintroductions and conservation, and developing a strategy for enhancing the long-term financial sustainability for managing the Kihansi Gorge ecosystem.

The story of the Kihansi Gorge and its protagonist, the tiny Kihansi spray toad, show how people working together from around the world can find solutions to conserve biodiversity for multiple benefits. This project is just one of thousands the GEF has supported to protect and conserve the wealth of animals and plants found on Earth in the places that need help the most.