Kihansi Spray Toad

Nectophrynoides asperginis

Kihansi Spray Toad (Nectophrynoides asperginis): Extinct in the Wild, Saved by Zoos

The Kihansi spray toad is a tiny golden toad that lived only in the waterfall spray meadows of Tanzania's Kihansi Gorge and gives birth to live toadlets. After a hydropower dam took most of the waterfall's water and chytrid fungus arrived, it was declared Extinct in the Wild in 2009. Toads rescued in 2000 and bred at the Bronx Zoo and Toledo Zoo saved the species, and zoo-bred toads have been released back into the gorge since 2012.

Habitat

Waterfall spray wetlands of grasses, mosses and ferns, about 600-940 m

Size

Adults about 1-3 cm; females larger than males; newborns about 5 mm

Diet

Tiny invertebrates; in zoos fruit flies, springtails and pinhead crickets

Range

About 2 hectares in the Kihansi Gorge, Udzungwa Mountains, Tanzania

Conservation

Extinct in the Wild (IUCN, since 2009); CITES Appendix I

Breeding

Internal fertilisation; females give birth to live toadlets, no tadpole stage

Habitat & range

The Kihansi spray toad was found in 1996 in the Kihansi River Gorge on the Udzungwa escarpment of Tanzania's Eastern Arc Mountains (WCS 2012). It lived only in a few small wetlands kept soaking wet by the spray of the waterfalls, an area of about 2 hectares. That is one of the smallest ranges of any land vertebrate (Lee et al. 2006), and searches at other waterfalls never found it anywhere else (Nahonyo et al. 2017). The constant mist kept the air humid and cool, so instead of forest the spray zone was covered in dense grasses, mosses and ferns (Nahonyo et al. 2017; IUCN Red List).

How to recognise it

It is tiny: adults are only about 1 to 3 cm long, and females are larger than males (AmphibiaWeb). The skin is golden yellow, often with a darker brown band along each side, and the belly skin is so thin that you can see the organs, and the developing young in pregnant females, through it (AmphibiaWeb; Lee et al. 2006). It has no eardrum and no air-filled middle ear, yet males still call to each other with soft, short notes during fights and courtship. Unlike many frogs, it is active by day (Arch et al. 2011).

Live birth

Most frogs and toads lay eggs that hatch into tadpoles. The Kihansi spray toad skips both. Fertilisation is internal, the young develop inside the mother, and she gives birth to fully formed toadlets about 5 mm long. Reported litter sizes range from 5 to 13 young in the wild, and Bronx Zoo keepers reported clutches of up to 24-28 eggs (AmphibiaWeb; Lee et al. 2006). In zoos the toads are fed tiny insects such as fruit flies and springtails, along with isopods and pinhead crickets (Nahonyo et al. 2017).

Conservation: lost in the wild, saved by zoos

The Lower Kihansi hydropower dam was built in 1999 and started producing power in 2000. It diverted the river into tunnels and cut the waterfall's flow by about 90 percent, so the spray wetlands dried out (WCS 2012; Nahonyo et al. 2017). In 2000, WCS and the Tanzanian government collected 499 toads from the gorge and flew them to the Bronx Zoo as an insurance colony (WCS 2010). Sprinklers were installed to replace the lost spray, but the wild population crashed in 2003 and the toads were gone by the mid-2000s (IUCN Red List). Chytrid fungus was the direct cause, the first known extinction of an African amphibian by disease (Weldon et al. 2020). The IUCN declared the species Extinct in the Wild in 2009 (WCS 2012). The rescued toads were shared among US zoos, but only the Bronx Zoo and the Toledo Zoo, whose colony came from the Detroit Zoo, managed to breed them, and they grew the population to thousands (WCS 2012; Nahonyo et al. 2017). In 2010, 100 toads were flown back to a breeding centre at the University of Dar es Salaam (WCS 2012). On 30 October 2012 about 2,000 zoo-bred toads were released into the gorge, the first time an amphibian declared Extinct in the Wild was returned to its home (WCS 2012; Ngalason et al. 2019). By May 2017, 8,669 toads had been released, but surveys found that few survived for long, and chytrid is still a threat (Ngalason et al. 2019; Weldon et al. 2020). The IUCN still lists it as Extinct in the Wild.

Fun facts about Kihansi Spray Toad

• Its whole wild range was about 2 hectares, roughly the size of three football pitches.
• It has no eardrum, but males still call to rivals and mates with soft, short notes (Arch et al. 2011).
• Mothers give birth to toadlets about 5 mm long, with no free-swimming tadpole stage.
• Its belly skin is see-through, so you can spot the babies inside a pregnant female.
• In 2012 it became the first amphibian declared Extinct in the Wild to be released back into its native habitat (WCS 2012).

Kihansi Spray Toad vs American Bullfrog (tiny vs huge)

The bullfrog wins easily: a spray toad would be a snack, not an opponent.

A just-for-fun pairing of two amphibians that never meet: the Kihansi spray toad comes from one waterfall gorge in Tanzania, while the American bullfrog lives in North American ponds and lakes. The spray toad is only 1 to 3 cm long. The bullfrog is one of the biggest frogs in North America and swallows almost any animal that fits in its mouth, including other frogs.

Read more about American Bullfrog.

More Amphibia animals

• Lemur Leaf Frog
• Olm
• Phawngpui Toad
• South China Giant Salamander
• Southern Corroboree Frog
• Tomato Frog

Amphibia · Water · Cost 1

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