Open Access Open Access  Restricted Access Subscription or Fee Access

Survivorship of the Reintroduced Kihansi Spray Toads Nectophrynoides asperginis in a Soft Release Experiment at the Kihansi Gorge, Tanzania

Nassoro Mohamed, Flora John Magige


The Kihansi Spray Toad (KST) Nectophrynoides asperginis is endemic to the unique wetland habitat surrounding the Kihansi Falls, Tanzania, with which it was associated. The species was declared extinct in the wild in 2009 by the International Union for Conservation of Nature (IUCN), following the loss of its unique habitat due to the diversion of the Kihansi River for hydropower production. This study is an initial attempt to determine the survivorship and possible sources of mortality of newborn and adult KSTs placed in cages in their original habitat in the Upper Spray Wetland (USW) and Lower Spray Wetland (LSW) areas. The cages were made of wooden frames covered with galvanized wire mesh to prevent the toads from escaping while allowing their prey (live invertebrates) to enter. There was a significantly higher survivorship of adult toads in the USW (29.2%) compared to those in the LSW (4.2%) (χ2 = 36.7, DF = 1, P < 0.0001). The newborn toads showed equally high survivorship rates in both USW (70%) and LSW (80%) (χ 2 = 0.1441, DF = 1, P = 0.7042). Newborn toads had a higher survivorship (75%) than adults (17%) (χ 2 = 16.7, DF = 1, P < 0.0001). Thus, we conclude that newborns were the more suitable life-stage for successful reintroduction of the KST back into its natural habitat. Therefore, we recommend continual reintroduction of newborn toads until the population stabilizes. Further studies should be conducted on other factors affecting the population dynamics of released KST, such as predation, diseases and both inter- and intra-specific competition. Maintenance of the habitat and constant monitoring programmes for the reintroduced KST should be continued.


Extinct in the wild, Kihansi Spray Toad, reintroduction, soft release, survivorship

Full Text:



Bertolero, A., D. Oro & A. Besnard. 2007. Assessing the Efficacy of Reintroduction Programmes by Modelling Adult Survival: The Example of Hermann’s Tortoise. Animal Conservation, 10: 360–368. Bouskra, D., C. Brézillon, M. Bérard, C. Werts, R. Varona, I.G. Boneca & G. Eberl. 2008. Lymphoid Tissue Genesis Induced by Commensals Through NOD1 Regulates Intestinal Homeostasis. Nature, 456: 507–510.

Channing, A., K.S. Finlow-Bates, S.E. Haarklau & P. Hawkes. 2006. The Biology and Recent History of the Critically Endangered Kihansi Spray Toad Nectophrynoides asperginis in Tanzania. Journal of East African Natural History, 95: 117–138. Cichoń, M & J. Kozlowski. 2000. Ageing and Typical Survivorship Curves Result from Optimal Resource Allocation. Evolutionary Ecology Research, 2: 857–870.

Cook, R.P. 2008. Testing the Potential and Limitations of Herpetofaunal Community Restoration in an Urban Landscape at Gateway National Recreation Area, NY/NJ. in R.E. Jung & J.C. Mitchell (Eds). Urban Herpetology. Society for the Study of Amphibians and Reptiles, Salt Lake City, Utah.

Cooke, A.S. & R.S. Oldham. 1995. Establishment of Populations of the Common Frog, Rana Temporaria, and Common Toad, Bufo bufo, in a Newly Created Reserve Following Translocation. Herpetological Journal, 5: 173–180.

Daly, G., P. Johnson, G. Malolakis, A. Hyatt & R. Pietsch. 2008. Reintroduction of the Green and Golden Bell Frog Litoria aurea To Pambula on the South Coast of New South Wales. Australian Zoologist, 34: 261–270.

Davis, T.M. & K. Ovaska. 2001. Individual Recognition of Amphibians: Effects of Toeclipping and Fluorescent Tagging on the Salamander Plethodon vehiculum. Journal of Herpetology, 35: 217‐225.

Duellman, W. & L. Trueb. 1994. Biology of Amphibians. JHU Press. London

Germano, J.M. & P.J. Bishop. 2009. Suitability of Amphibians and Reptiles for Translocation. Conservation Biology. 23: 7–15.

Hoffmann, M., C. Hilton-Taylor, A. M. Angulo, Bohm, M. Brooks, S. Butchart, K. E. Carpenter, J. Chanson, B. Collen & N.A. Cox. 2010. The Impact of Conservation on the Status of the World’s Vertebrates. Science, 330: 1503–1509.

IUCN. 1998. IUCN Guidelines for Re-Introduction. Prepared By the IUCN/SSC Reintroduction Specialist Group. IUCN, Gland, Switzerland and Cambridge, UK. 10 Pp.

IUCN. 2006. Global Amphibian Assessment. Accessed on 16 November 2018.

IUCN. 2009. IUCN Red List of Threatened Species. Www.Redlist.Org. Accessed on 16 November 2018

Kleinbaum D.G. & M. Klein. 2012. Survival Analysis: A Self-Learning Text, Third Edition, Statistics for Biology and Health, Springer-Verlag, New York

Kolby, J.E., G.E. Padgett-Flohr & R. Field. 2010. Amphibian Chytrid Fungus Batrachochytrium dendrobatidis in Cusuco National Park, Honduras. Diseases of Aquatic Organisms, 92: 245 – 251.

Lee, S., K. Zippel, L. Ramos & J. Searle. 2006. Captive-Breeding Programmes for the Kihansi Spray Toad at the Wildlife Conservation Society, Bronx, New York. International Zoo Yearbook, 40: 241–253.

LKEMP. 2004. Updated Environmental Management Plan for the Lower Kihansi Hydropower Project. Dar es Salaam: Submitted To Vice President Office NEMC.

Makange, M., N. Kulaya, E. Biseko, P. Kalenga, S. Mutagwaba & G. Misinzo. 2014. Batrachochytrium dendrobatidis Detected in Kihansi Spray Toads at a Captive Breeding Facility (Kihansi, Tanzania). Diseases of Aquatic Organisms, 111, 159–164, 2014 Doi: 10.3354/Dao02775.

Malago, J.J. 2019. Histopathological Diagnosis of Diseases Affecting Amphibians Inhabiting Kihansi Gorge, Tanzania. Tanzania Journal of Science, 45(4): 608–617.

Moore, M.C., C.W. Thompson & C.A. Marler. 1991. Reciprocal Changes in Corticosterone and Testosterone Levels Following Acute and Chronic Handling Stress in the Tree Lizard, Urosaurus ornatus. General and Comparative Endocrinology, 81: 217–226.

Msuya, C.A. & N. Mohamed. 2019. Reintroduction of the Kihansi Spray Toad Nectophrynoides asperginis Back to Its Natural Habitat by Using Acclimatizing Cages Tanzania. Journal of Science, 45(4): 570–583.

Mtui, D., F.H.A. Khatibu & G. Misinzo. 2008. Observation on the Status of Amphibians in Kihansi Gorge, Tanzania and Potential Species for Biological Control Against Chytridiomycosis. In: Proceedings of the 13th Meeting of the African Amphibian Working Group (AAWG). 12–13 April, 2008, Arusha, Tanzania.

Mullen, E.B. & P. Ross. 1997. Survival of Relocated Tortoises: Feasibility of Relocating Tortoises as a Successful Mitigation Tool. in Proceedings Conservation, Restoration, and Management of Tortoises and Turtles: A n International Conferences: 140–146.

Mutagwaba, S.J. & J.R.M. John. 2014. Kihansi Spray Wetlands Under Mitigation Measures and Its Implication to the Biodiversity of the Resultant Ecosystems. Journal of Biodiversity and Environmental Sciences, 5: 204–213.

Odum, E. P. 1971. Fundamentals of Ecology. Philadelphia, PA: W.B, Saunders.

NORPLAN. 2002. Lower Kihansi Hydropower Project. Immediate Rescue and Emergency Measures. Final Specialist Report:Amphibian Studies. Dar es Salaam, Tanzania: Report Produced for Tanzania Electric Supply Company Ltd (TANESCO). Olney, P.J.S., G.M. Mace & A.T.C. Friesner. 1994. Creative Conservation. Interactive Management of Wild and Captive Animals. Chapman & Hall, London, UK. ISBN -0 412 49570 8.

Phillips, C.T. & J.N. Fries. 2009. An Evaluation of Visible Implant Elastomer for Markingthe Federally Listed Fountain Darter and the San Marcos Salamander. North American Journal of Fisheries Management, 29: 529‐532.

Poynton, J.C., K.M., Howell, B.T. Clarke & J.C. Lovett. 1998. a Critically Endangered New Species of Nectophrynoides (Anura: Bufonidae) from the Kihansi Gorge, Udzungwa Mountains, Tanzania. African Journal of Herpetology, 47: 59-67.

R Core Development Team. 2018. R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna, Austria.

Rich, J.T., J.G., Neely, R.C. Paniello, C.C. Voelker, B. Nussenbaum & E.W. Wang. 2010. a Practical Guide To Understanding Kaplan-Meier Curves. Otolaryngology Head and Neck Surgery, 143(3): 331–336. Https://Doi.Org/10.1016/J.Otohns.2010.05.007

Sarrazin, F. & S. Legendre. 2000. Demographic Approach to Releasing Adults Versus Young in Reintroductions. Conservation Biology, 14: 488–500.

Short, J. & B. Turner. 2000. Reintroduction of the Burrowing Bettong Bettongia Lesueur (Marsupialia: Potoroidae) To Mainland Australia. Conservation Biology, 96: 185–196.

Skerratt, L.F., L. Berger, R. Speare, S. Cashins, K.R. Mcdonald, A.D. Phillott, H.B. Hines & N. Kenyo. 2007. Spread of Chytridiomycosis Has Caused the Rapid Global Decline and Extinction of Frogs. Ecohealth, 4: 125–134.

Stephens, P.A. & W.J. Sutherland. 1999. Consequences of the Allee Effect for Behaviour, Ecology and Conservation. Trends in Ecology and Evolution. 14: 401–405.Stuart, S.N., J.S. Chanson, N.A. Cox, B.E. Young, A.S. Rodriguez, D.L. Fischman & W. Waller. 2004. Status and Trends on Amphibian Declines and Extinction Worldwide. Science, 306: 1783–1786.

Stuart, S.N., J.S. Chanson, N.A. Cox, B.E. Young, A.S. Rodriguez, D.L. Fischman & W. Waller. 2004. Status and Trends on Amphibian Declines and Extinction Worldwide. Science, 306: 1783–1786.

Tavecchia, G., C. Viedma, A. Martinez-Abrain, M.A. Bartolome, J.A. Gomez & D. Oro. 2009. Maximizing Reintroduction Success: Assessing the Immediate Cost of Release in a Threatened Waterfowl. Biological Conservation, 142: 3005–3012.

Tocher, M.D., D. Fletcher & P.J. Bishop. 2006. A Modeling Approach To Determine a Translocation Scenario for the Endangered New Zealand Frog Leiopelma hamiltoni. Herpetological Journal, 16: 97–106.

Tuberville, T.D. & Buhlmann, K.A. 2014) Final Report on Kihansi Spray Toad Efforts During 2012–2013, Including Progress Report for December 2012-July 2013. Report University of Dar es Salaam.

Weldon, C. & D. Mtui. 2006. Follow Up Survey at Kihansi Gorge for the Presence of Amphibian Chytrid Fungus. Dar es Salaam, Tanzania: Final Report. LKEMP.

Weldon, C. & L.H. Du Preez. 2004. Decline of the Kihansi Spray Toad, Nectophrynoides asperginis, from the Udzungwa Mountains, Tanzania. Froglog, 62: 2−3.

World Bank. 2002. Lower Kihansi Hydropower Project (LKHP) Environmental Review in Support of the National Environmental Management Council – Finalreport. Washington D.C.,USA: World Bank.


  • There are currently no refbacks.