This is the time of year when we take stock of the success of the years Pearl-bordered Fritillary all too short fight period. The news is not very good as once again despite our best efforts in providing the habitat the weather has stepped in with rain overcast skies and strong cold winds, not ideal breeding conditions for a small rare butterfly. Some have been seen and with the past few days of sunshine hopefully the late fliers will be able to get out there and lay some eggs in hope of a sunny spring next year.
On the subject of habitat within conservation there are often difficult decisions to be made around management options. One of these conundrums is developing on the side of the gorge below Castle Drogo.
For many years Piddledown common has been managed to benefit the Fritillary butterfly for a while the High Brown and Dark Green Fritillaries hung on but a series of poor summers saw them disappear now the Pearl bordered and small Pearl-bordered Fritillaries have the place to themselves.
Nationally the Pearl-bordered Fritillary is declining at an alarming rate, it was a species of coppice woodland, following the woodman as he cut parts of the wood on rotation, violets (the caterpillars food plant) growing profusely in the newly cut areas, allowing the butterfly to breed in the sheltered sunny clearings. As woodland management declined after the war so too did the butterfly the remaining colonies clinging on in scrubby grass–heaths with violets growing under a bracken ‘canopy’, particularly in the west where Dartmoor is seen as a ‘stronghold’.
Our management has ensured the well being of the butterfly for the last 20 years and populations are still viable. However nothing in nature is static and the habitat is slowly changing the bracken is less vigorous and new plants are beginning to spread.
The main culprit is our iconic woodland favourite the Bluebell its gift of colour and scent the subject of art, poetry and song. The problem is they also form dense mats of vegetation in the areas where the Fritillaries breed forcing out the violets and cooling the environment where the dead bracken used to absorb the heat of the sun and raise the temperature for the caterpillars to develop. In some places Bluebells have wiped out small colonies of Fritillaries.
So the dilemma is do we leave to site to develop into a sea of glorious scented blue matching the swathes of spring blue common in many other woods. Everybody visiting the area will gaze at the colours and smell the perfume and wonder at the beauty of nature.
Or do we try and restrict the spread of this headlining plant to protect the dainty but often overlooked violets and the rare and declining Fritillary which to those with an eye to see are also wonders of natures handy work, but easily overlooked by the casual observer.
And what happens if the bluebells in particular spread further onto these small and very select areas of butterfly habitat do we actively control them? Can you see the head lines ‘’National Trust wipe out bluebells’’!!! Whereas if the Fritillary slowly disappeared how many people would notice?
Which way would you go?