The Duke of Burgundy butterfly is most certainly a very threatened species locally. Butterfly enthusiasts searching for it in late May (over the years the most productive time) might have considered this year one of the worst for our local Duke populations. In fact 2007 was no worse than 2006 and might have been an improvement over last year.

A male Duke at Ivinghoe Beacon in 2007
Photo © Nick Bowles

At various sites the Dukes flew early and managed to lay some eggs before the time of their normal peak emergence in late May; when poor weather led to many people failing to see any Dukes at all. When the weather improved in June two sites (at least) continued to produce sightings and probably the Duke also continued to lay eggs.

Duke of Burgundy distribution 2006
(Data from Levana)

So while the numbers of Dukes seen on any one day were below the maxima recorded at each site visited, the flight period was extended and observation of ova and larvae suggests that things ended no worse than in previous, recent years.

The fact remains that this species is now restricted to 10, or fewer, colonies within the UTB area - and some of these colonies are extremely small.

The 2006 distribution of the Duke of Burgundy. A distribution that stayed approximately unchanged in 2007.

Some effort is going into conserving the butterfly at most of these sites and a massive effort is made at a few. Unfortunately the butterfly is extremely capricious and why it chooses to lay its eggs on certain plants (usually cowslip, sometimes primrose) and not others remains obscure.

'Typical' egg-laying site, with 4 eggs on cowslip beneath a scrubby bush in longish but sparse grass.

Duke of Burgundy egg-laying habitat
Photo © Nick Bowles