As our Common Toads start to enter hibernation after a tricky weather year; Becky Austin our Croaking Science Volunteer, talks about how climate change affected one of their cousins in Costa Rica.
The very first species whose extinction was blamed on climate change due to anthropogenic causes was an amphibian: the Golden Toad. Once abundant in a small area of the Costa Rican cloud forests of Central America, the last individual sighting was in 1989 and in 2004, the toad was stated as extinct.
Golden Toads, or Bufo periglenes, were only 5cm long and showed sexual dimorphism: males had bright ‘golden’ skin, whereas females had olive skin with red spots and a yellow rim. Golden toads also showed the extraordinary feature of ‘gastric breeding’, where eggs were kept in the stomach of the female until the tadpoles were ready to leave via the mouth.
How was climate change to blame for the extinction of this fascinating species? Recent discoveries may show that the toad’s extinction coincided with a very dry period of time caused by an El Niño event in 1986-7 (where a warm Pacific current affected the South American climate). This caused breeding pools to dry out and population numbers to crash as few tadpoles could survive. However, this alone may not be the cause.
Gobal warming is causing consistent atmospheric temperature changes in most parts of the world, including the toad’s home range in Costa Rica. Many scientists believe that in these highland areas, conditions are increasingly becoming more suited to the prolific growth of the chytrid fungus Batrachochytrium dendrobatidis, which may have caused the extinction of the golden toad. Even if the fungus initially spread due to the conditions the El Niño caused in the late 80s, continual warming will increase the fungus’s rate of destruction, leading to many further amphibian extinctions. Global warming must therefore be addressed as quickly as possible as the root of many species extinctions.
What can you do to help?
Check out our website and get clued up about chytrid fungus and what it looks like; so you can report any potential sightings of the disease.
Donate to Froglife this year and help us continue our work with amphibians and reptiles in 2014
Pounds, J.A., Bustamante, M.R., Coloma, L.A., Consuegra, J.A., Fogden, M.P.L., Foster, P.N., La Marca, E., Masters, K.L., Merino-Viteri, A., Puschendorf, R., Ron, S.R., Sanchez-Azofeifa, G.A., Still, C.J. and Young, B.E. (2006). Widespread amphibian extinctions from epidemic disease driven by global warming. Nature, 439: 161-167.
Anchukaitis, K.J . and Evans, M.N. (2010). Tropical cloud forest climate variability and the demise of the Monteverde golden toad. PNAS, 107: 5036-5040.