28 January 2014 Last updated at 08:08 GMT
The mild winter is encouraging thousands of migratory birds to stay in the UK rather than head off to warmer climes abroad.
Staff at the Wildfowl and Wetlands Trust at Slimbridge in Gloucestershire say record numbers of species, such as ducks, wigeons, lapwings and golden plovers, are being recorded.
The weather has also led to the early arrival of a litter of seven harvest mice, the smallest species of British rodent.
The BBC's Steve Knibbs reports.