Fans of BBC TV's Winterwatch will have enjoyed this year's film on an intriguing study of butterfly hibernation that Malcolm Hull, Chair of Herts and Middlesex Butterfly Conservation, has been conducting at his home in St Albans.

After four years of monitoring scores of Small Tortoiseshell and Peacock butterflies that seek 'winter' shelter in a brick shed extension, Malcolm has discovered that the former in some years start hibernation as early as late June, with a major influx at the start of July. This is far earlier than 'the end of summer' suggested by field guides.

Since Butterfly Conservation's 'Big Butterfly Count' takes place around the end of July and beginning of August, it may also help explain fluctuations from year to year in the number of Small Tortoiseshells being sighted.

Those who missed the TV film can still watch it using the BBC iPlayer.  You can also read a paper by Malcolm on his latest findings on the Herts & Middlesex Butterfly Conservation website.

*Sharp-eyed viewers will notice that the book Malcolm is filmed consulting ? with a colourful Peacock on its front cover ? is the HNHS's own best-selling Butterflies of Hertfordshire and Middlesex by Andrew Wood!