A collaboration of coast and countryside organisations on The Lizard Peninsula

Exeter University research investigates the importance of temperature for rare butterfly.
2019 is proving to be a year of climatic extremes. Hot, sunny weather back in February saw the mercury hitting 20°C in some parts of the country, while in July the UK’s all-time maximum recorded temperature was exceed with a new record of 38.7 °C. Current research at the University of Exeter is helping to uncover how temperature affects our wildlife, with a special focus on one of the Lizard’s threatened species butterfly.

A male Silver-studded Blue butterflyA male Silver-studded Blue butterfly

The Silver-studded Blue is a scarce butterfly in Britain, that can be found on the heaths and coastal grasslands of the Lizard. Elsewhere in Cornwall, it also occurs on sand dunes and some of the former mining sites in the region. This butterfly has a rather unusual lifecycle in that it has a special relationship with certain species of ant. The caterpillars produce a sweet, sugary liquid to reward ants, which in return protect it from predators and even let it live inside their nest. Because of this close association between butterfly and ant, Silver-studded Blues can only be found in places where the right species of ant occurs at high enough densities.

A black Lasius ant – the host species associated with Silver-studded BluesA black Lasius ant – the host species associated with Silver-studded Blues

Our research is investigating how both habitat conditions and temperature constrains the distribution of the butterfly and its associated ants. Temperature can vary greatly on a scale of centimetres or metres due to the influence of topography and vegetation. For small, cold-blooded insects, this fine-scale variation in “microclimate” can be very important in determining where they can and can’t live. We are studying this relationship with temperature at sites across Cornwall, looking at where the Silver-studded Blue and its host ants can be found, and what the habitat and microclimate conditions are like in these locations. One such site is the National Trust’s Penrose estate, where we are also looking at how the activity of Silver-studded Blues varies with different weather conditions and the time of day. This should help to give us a more mechanistic understanding about how environmental conditions directly affect the butterfly. By better understanding the factors important for allowing species to persistence within landscapes, we can improve our ability to predict how these species are likely to respond to future environmental changes.

Published: Sept 2019
Author: Marcus Rhodes (Exeter University)