The catastrophic declines in frog and salamander populations in recent years may be even more widespread than had been feared 鈥� and the devastation seems to extend to reptiles.
Steven Whitfield at Florida International University in Miami, US, and colleagues studied data on ground-dwelling reptiles and amphibians collected over the past 35 years at La Selva Biological Station in Costa Rica.
The counts show a decline of around 75% in reptiles and amphibians in native forest since 1970. But the numbers of both increased in abandoned cacao plantations, by 4% annually for amphibians, and 2.7% per year for reptiles.
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Fungal diseases or pesticide contamination, blamed for amphibians鈥� decline elsewhere, are unlikely to be behind the declines at La Selva, since they would affect abandoned plantations as well as native forest.
The researchers suggest the cause may be a change to a warmer, wetter climate, which reduces tree growth and may lead to a thinner layer of leaf litter, where the animals live. Cacao plantations (which produce cocoa) produce a heavier layer of this leaf litter.
Pesticides and fungi have previously been blamed for the decline in Costa Rica鈥檚 mountain amphibians (see Mountain frogs succumb to highflying pesticides).
Journal reference: Proceedings of the National Academy of Sciences (DOI: 10.1073/pnas.0611256104)
