Today, at the fourth attempt I located one of Britain’s rarest butterflies in its local stronghold. Black Hairstreak is restricted to a belt of mostly woodland sites stretching north from Oxford through Buckinghamshire and into Cambridgeshire. BBOWT’s Whitecross Green Wood has become my location of choice in the last two seasons, since in my view some other Bernwood Forest sites have become over visited and I do not wish to contribute to that.
Myself and other hopeful observers began prospecting here from 4th June. On my second visit three days later a local expert predicted these Hairstreaks would begin flying in this month’s third week, following upon cold nights through May. That had been the usual emergence date until becoming earlier over the last few years. Her forecast proved to be spot on as BH were first seen at WGW and three more sites in Bucks from15th June.
I arrived at a regular hot spot in strong mid-afternoon sunshine, quickly finding 3 – 4 Black Hairstreak flying around the tops of a tall stand of Blackthorn. But these butterflies were not inclined to settle. As the sun weakened between 4 and 5pm they began to perch closer in lower growing Blackthorn. Even then they displayed the annoying tendencies to either lie side on to the sun upon settling, as BH do or adopt other difficult angles to my camera lens.
This was also not an easy spot for photography as there was no Wild Privet in bloom amongst the Blackthorn. When nectaring on that food plant BH are not prone to distraction and so allow a close approach. But when feeding on aphid honeydew, which I assume they were today, they tend to half conceal themselves in the curves of upturned leaves. Eventually acceptable shots were gained though, if from some slightly unusual angles (above).
The particular insect (pictured above) must be the Ricky Hatton of the Black Hairstreak world. That’s a lot of war wounds for a maximum four days on the wing. But this butterfly has a short flight period in which to defend its territory and mate, and I have noticed how quickly they deteriorate in previous seasons. Numbers are expected to peak before the end of June, then it will all be over for another year. In the interim many visitors are likely to pressurise the Bernwood Forest sites, but I for one will not seek out this rarity again in 2015.