The big pond thaw
This winter has been the hardest for over 30 years in Scotland with temperatures, in Assynt, down to -12°C.
Because of this, many garden ponds froze for much longer than we have been used to. Ice cover has persisted for a month or more in many places. As the ice has started to melt people are now finding find dead amphibians, mainly Common Frogs (Rana temporaria), that had been overwintering in their ponds.
It seems that the large frogs are more susceptible. Work by the Freshwater Habitats Trust, formerly Pond Conservation, has shown that most die from lack of oxygen rather than being frozen. Therefore shallow ponds with lots of pond weed and not too many dead leaves are much better than deep ponds for overwintering amphibians.
A. Summers