The Duke of Burgundy (Duke) is a beautiful rare butterfly which has a colony in Denge Wood. Its two main populations there are at Bonsai Bank (Forestry England) and the Warren (Woodland Trust), with individuals found in other parts of the wood linking them. They fly in May, with a few emerging in late April if the weather is warm, and by June they are gone until next year.
Dukes are small butterflies, being not much bigger than a thumbnail when they close their wings. The males and females look the same unless studied closely, but behave slightly differently. The males tend to bask in the sun and perch on vegetation up to 1.5m high. They are quite territorial, so can often be seen flying to battle with interlopers. The females are more secretive, and can sometimes be seen laying eggs on Primroses or Cowslips. Dukes sometimes take nectar from flowers and particularly seem to like Wood Spurge.
In 2008, Butterfly Conservation started a 3 year project to help the Duke of Burgundy at Denge Wood, as its population had dwindled to a dangerously small number. Over those years monitoring was set up, and winter work parties started for conservation management of the colony sites. This improved and maintained the habitat for the butterfly, ensuring that the caterpillar foodplants, mainly Primroses, were abundant and in optimum condition. This work has continued ever since, and last year Dukes had one of their best years since the project began. However, the colony is still small.
The two populations at Denge Wood are separated by areas of private woodland, although joined by a Public Right of Way. Work has been done to open up this link so that Dukes can easily fly between populations, and also colonise the woodland edge along the path.
Please do come to see these lovely butterflies on a warm day in May at Bonsai Bank or the Warren. If you are fortunate enough to own some woodland in this area, keep your eyes open as you may get some on your land. If you provide them with open glades and primroses they may even set up home.
[Claire Ward, Butterfly Conservation Volunteer]