The depths of winter are typically a quiet time for butterflies and moths but this doesn’t mean there’s nothing of interest going on in the world of Lepidoptera.
In fact, the colder months see some of our more hardy species adopting extraordinary strategies to survive the winter.
And it was this story that we wanted to tell when we contacted the BBC Springwatch team last summer after they told us they would be filming their Winterwatch spin-off at the RSPB’s beautiful Arne reserve - just a stone’s throw from our Dorset HQ.
Studland Heath, a wild and windswept expanse of gorse and heather nestling up against the white sand beaches of Studland Bay, is not only a wildlife oasis but also played a key role in the defence of the UK’s southern border during World War Two. For this coastline is studded with pill boxes – low concrete structures hunkering down amidst the grassland that were used as wartime lookout points to give early warning of an enemy attack.
But as the soldiers moved out the wildlife moved in. These structures now provide shelter for overwintering butterflies which endure the cold by going into a deep state of torpor known as diapause. Clustered together in small groups inside the pill boxes adults temporarily shut down their development, only starting up again once the temperatures rise and daylight hours lengthen.
You might think that these sedentary specimens would be easy targets for hungry rodents, and true, the floor of some pillboxes were littered with partially chewed Peacock wings. But the butterflies are not totally helpless. With minimum expenditure of energy they can flare their wings – terrifying attackers with their vibrant patterns.
Winterwatch were keen to cover the story and after their researchers spent hours on the phone picking the brains of our diapause expert Richard Fox, BC staff were despatched in November onto the heath to find the perfect pillbox.
This task proved easier said than done. Peacocks, it appears are picky. Some pillboxes were too wet, some too drafty, and some, by the level of butterfly remains littering the floor, were just too dangerous.
Finally we found a perfect spot. Inside, clinging to the roof and walls were around 20 Peacocks, a dead slow worm and an empty can of cider.
Winterwatch presenter Gillian Burke and the production team arrived on site for filming on a freezing cold January morning just days before the programme was due to be broadcast.
Filming, it appears, takes a long time. A full day’s work was needed for the team to get the shots they wanted for a package that was just three minutes long.
The trickiest element was encouraging the Peacocks to perform their threat display. A combination of light blowing and the scraping of nails down the brick roof eventually provoked one feisty specimen to flare its wings in rage – key shot captured!
Elsewhere, BC’s moth expert Mark Parsons was on hand to provide background information for a piece explaining how some moths see out the coldest months. Luckily, despite a freezing and foggy night, Mark tracked down some specimens of the Herald Moth and Winter Moth that performed obligingly for the live cameras.
So with a little help from BC, Winterwatch successfully managed to reveal that the deep midwinter is still a great time to spot the extraordinary behaviour of our moths and butterflies.
Liam Creedon
Head of Media
Follow me on Twitter @Liamcreedon