RARE butterfly species are winging their way back to Oxfordshire because of last year’s warm spring.

Butterfly experts say the conditions last spring were perfect for the insects, which emerged weeks earlier than normal, as they appealed yesterday for people in Oxfordshire to help monitor species this year.

Data collected by the UK Butterfly Monitoring Scheme revealed population rises for a number of species that have declined in recent years and scientists are hoping there will be similar increases this year, following hot weather in March.

Volunteers have been collecting data from about 1,000 sites across the UK and ecologist Dr Marc Botham, from the Centre for Ecology and Hydrology in Benson Lane, Crowmarsh Gifford, said people should look out for some scarce species in Oxfordshire.

Dr Botham said: “Increasingly warm spring weather in recent years has really benefited a number of scarce species. Volunteers have worked hard to improve the condition of current habitats by cutting back woodland to create open areas where violets and other plants can grow. The hot weather in March will have helped but it could be quite cold in April and May so that could set the spring butterflies back a bit.”

Dr Botham added that people can look out for the Grizzled Skipper throughout Oxfordshire at sites including Aston Rowant and Aston Upthorpe Downs, and the Dingy Skipper at sites including Swyncombe Downs in the Chilterns.

He said: “Both are localised scarce species that have shown significant long-term declines but had a superb year in 2011.”

For details about the UK Butterfly Monitoring Scheme, visit ukbms.org