Skip to main content

Ecology and demography of the Critically Endangered Kandian torrent toad Adenomus kandianus: a long-lost endemic species of Sri Lanka

  • Suranjan Karunarathna (a1), Sujan Henkanaththegedara (a2), Dinesh Gabadage (a3), Madhava Botejue (a3), Majintha Madawala (a4) and Thilina D. Surasinghe (a5)...

The tropical island nation of Sri Lanka is a biodiversity hotspot with a high diversity and endemism of amphibians. The endemic, stream-dwelling Kandian torrent toad Adenomus kandianus is Critically Endangered and was considered to be extinct until its rediscovery in 2012. The species is now known from two localities in tropical montane forests. We conducted a 4-year study using transect surveys and opportunistic excursions to assess habitat associations, demographics and abundance of A. kandianus in and around Pidurutalagala Conservation Forest. We recorded a mean of 44.25 post-metamorphs per year, with a density of < 1 individual per 100 m2, with occurrence within a narrow extent (c. 0.005 km2) of the stream channel. Behaviour and microhabitat selection varied depending on sex and stage of maturity. The species preferred moderately sized montane streams with rocky substrates and woody debris, colder temperatures, and closed-canopy, intact riparian forests. We noted size-based reversed sexual dimorphism and a strong ontogenetic relationship between snout–vent length and body weight. Anthropogenic activities such as intensive crop farming deterred the species; proximity to croplands had a negative influence on abundance. We recommend re-delineation of the boundary of Pidurutalagala Conservation Forest to incorporate the toad's habitat into the core of the reserve and thus limit the impacts of human activities. Conservation and management actions such as ex-situ breeding, population monitoring, and restoration of degraded habitats could also contribute towards the persistence of this toad. Our findings provide useful insights into ecological research on and conservation of range-restricted aquatic amphibians.

Corresponding author
(Corresponding author) E-mail
Hide All
Blaustein, A.R., Wake, D.B. & Sousa, W.P. (1994) Amphibian declines: judging stability, persistence, and susceptibility of populations to local and global extinctions. Conservation Biology, 8, 6071.
Didham, R.K., Tylianakis, J.M., Hutchison, M.A., Ewers, R.M. & Gemmell, N.J. (2005) Are invasive species the drivers of ecological change? Trends in Ecology & Evolution, 20, 470474.
Dudley, N. (2008) Guidelines for Applying Protected Area Management Categories. IUCN, Gland, Switzerland.
Gabadage, D.E., De Silva, A., Botejue, W.M.S., Bahir, M.M., Surasinghe, T.D., Madawala, M.B. et al. (2014) On the discovery of second living population of Adenomus kandianus (Günther, 1872) from Sri Lanka: with the bioecology, and detailed redescription to the species. Herpetotropicos, 10, 3749.
IUCN SSC Amphibian Specialist Group (2012) Adenomus kandianus. The IUCN Red List of Threatened Species 2012: e.T54458A17511456. Http:// [accessed 18 May 2016].
Karunarathna, D.M.S.S., Henkanaththegedara, S.M., Amarasinghe, A.A.T. & De Silva, A. (2013) Impact of vehicular traffic on Herpetofaunal mortality in a savannah forest, eastern Sri Lanka. Taprobanica, 5, 111119.
Meegaskumbura, M., Bossuyt, F., Pethiyagoda, R., Manamendra-Arachchi, K., Bahir, M., Milinkovitch, M.C. & Schneider, C.J. (2002) Sri Lanka: an amphibian hot spot. Science, 298, 379.
Meegaskumbura, M., Senevirathne, G., Wijayathilaka, N., Jayawardena, B., Bandara, C., Manamendra-Arachchi, K. & Pethiyagoda, R. (2015a) The Sri Lankan torrent toads (Bufonidae: Adenominae: Adenomus): species boundaries assessed using multiple criteria. Zootaxa, 3911, 245261.
Meegaskumbura, M., Wijayathilaka, N., Abayalath, N. & Senevirathne, G. (2015b) Realities of rarity: climatically and ecologically restricted, critically endangered Kandian Torrent Toads (Adenomus kandianus) breed en masse. PeerJ PrePrints, 3, e1964.
MOE (Ministry of Environment) (2012) The National Red List 2012 of Sri Lanka; Conservation Status of the Fauna and Flora. Biodiversity Secretariat, Ministry of Environment, Colombo, Sri Lanka.
Olson, D.H., Anderson, P.D., Frissell, C.A., Welsh, H.H. Jr & Bradford, D.F. (2007) Biodiversity management approaches for stream–riparian areas: perspectives for Pacific Northwest headwater forests, microclimates, and amphibians. Forest Ecology and Management, 246, 81107.
Pethiyagoda, R., Manamendra-Arachchi, K., Bahir, M.M. & Meegaskumbura, M. (2006) Sri Lankan amphibians: diversity, uniqueness and conservation. In The Fauna of Sri Lanka: Status of Taxonomy, Research and Conservation (ed. Bambaradeniya, C.N.B.), pp. 125133. The World Conservation Union, Colombo, Sri Lanka & Government of Sri Lanka.
R Development Core Team (2011) R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna, Austria.
Refsnider, J.M. & Janzen, F.J. (2010) Putting eggs in one basket: ecological and evolutionary hypotheses for variation in oviposition-site choice. Annual Review of Ecology, Evolution, and Systematics, 41, 3957.
Richter, B.D., Braun, D.P., Mendelson, M.A. & Master, L.L. (1997) Threats to imperiled freshwater fauna. Conservation Biology, 11, 10811093.
Sampath, K., Kennedy, I.J.J. & James, R. (2002) Pesticide impact on excretory physiology of the common frog, Rana tigrina (Daud) tadpoles. Bulletin of Environmental Contamination and Toxicology, 68, 652659.
Semlitsch, R.D. & Bodie, J.R. (2003) Biological criteria for buffer zones around wetlands and riparian habitats for amphibians and reptiles. Conservation Biology, 17, 12191228.
Skelly, D.K. (1994) Activity level and the susceptibility of anuran larvae to predation. Animal Behaviour, 47, 465468.
Sodhi, N.S., Bickford, D., Diesmos, A.C., Lee, T.M., Koh, L.P., Brook, B.W. et al. (2008) Measuring the meltdown: drivers of global amphibian extinction and decline. PLoS ONE, 3(2), e1636.
Stuart, S.N., Hoffmann, M., Chanson, J.S., Cox, N.A., Berridge, R.J., Ramani, P. & Young, B.E. (eds) (2008) Threatened Amphibians of the World. Lynx Edicions, Barcelona, Spain.
Surasinghe, T.D. (2009) Conservation and distribution status of amphibian fauna in Sri Lanka. Biodiversity, 10, 317.
Tejedo, M. (1992) Effects of body size and timing of reproduction on reproductive success in female natterjack toads (Bufo calamita). Journal of Zoology, 228, 545555.
UNESCO (2016) World Heritage List. Http:// [accessed 2 March 2016].
Werner, W. (1988) Human impact on natural environment in the Central Highlands of Sri Lanka. Universitas, 30, 2937.
Wickramasinghe, L.J.M., Bandara, I.N., Vidanapathirana, D.R., Tennakoon, K.H., Samarakoon, S.R. & Wickramasinghe, N. (2015) Pseudophilautus dilmah, a new species of shrub frog (Amphibia: Anura: Rhacophoridae) from a threatened habitat Loolkandura in Sri Lanka. Journal of Threatened Taxa, 7, 70897110.
Wickramasinghe, L.J.M., Vidanapathirana, D.R. & Wickramasinghe, N. (2012) Back from the dead: the world's rarest toad Adenomus kandianus rediscovered in Sri Lanka. Zootaxa, 3347, 6368.
Woolbright, L.L. (1983) Sexual selection and size dimorphism in anuran amphibia. The American Naturalist, 121, 110119.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

  • ISSN: 0030-6053
  • EISSN: 1365-3008
  • URL: /core/journals/oryx
Please enter your name
Please enter a valid email address
Who would you like to send this to? *



Altmetric attention score

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed