Many rivers and ponds were running low after months of drought.
The Royal Society for the Protection of Birds said wading birds have been hit hard, The Guardian reported. At the Ouse Washes reserve in Cambridgeshire, the society estimates at least 600 nests have been destroyed.
"Following centuries of land drainage across the U.K., the Ouse Washes is now the most important stronghold for these birds, after they have been largely forced out of other sites," said Jon Reeves, the reserve's site manager. "Literally, we have all our eggs in one basket and we've lost them. It's devastating to watch the nests succumb to the rising waters without being able to do anything to prevent it."
A spokesman for the Environment Agency said the rain, which hit a historic record in April, has reduced the likelihood of fires on heaths and moors, helping birds that nest there. The spokesman said more water in ponds and rivers improves the chance that fish, newts and dragonflies will reproduce successfully.