Butterfly benefits from warmer springs?

The Duke of Burgundy (picture courtesy of the BBC), one of the UK’s rarest butterflies, appears to be set to be benefit from climate change. For the first time in Britain the population of these butterflies in Gloucestershire has been recorded this month as producing a second brood - something which happens regularly further south in Europe but has not been recorded before in the UK. The butterfly normally produces one brood per year, taking to the wing in late April, but warmer springs have seen the April emergence taking place earlier in recent years and presumably the warmer weather has prompted the caterpillars to become pupae and then adult insects within weeks instead of over-wintering as pupae and emerging the following spring. If this trend continues it could help stem the decline of the Duke of Burgundy whose numbers have dropped by 60% over the past decade, and which is now found at only a limited number of sites on the chalk downland of southern England.