The role of dispersal in species' ability to respond to climate change

There is an emerging consensus that many animal species are responding to current climate warming by shifting their distributions northwards. However, in order to track climate, species must be able to disperse through landscapes that have been greatly altered by human activities, and where breeding habitats are often fragmented and scattered across inhospitable urban and agricultural landscapes. Because of this human-induced habitat loss, many species with poor dispersal ability are failing to shift their ranges and are unable to reach new sites beyond their current range margin. Predicting why some species can shift their ranges in response to climate change whilst others cannot, is crucial for improving our projections of species' future distributions. This project will address this issue by investigating species' dispersal behaviour and capability. Even if greenhouse gas emissions were greatly reduced immediately, more warming would still occur due to inertia in the Earth's climate system. Thus, there is a commitment to future warming regardless of any mitigation and, in this context, adaptation measures are required urgently. One commonly suggested adaptation measure is the creation of more permeable landscapes that enable species to movement through degraded landscapes, and help them colonise new sites. However, the effectiveness of improving habitat connectivity for promoting range shifts is essentially untested. There are currently no data examining how species' flight behaviour in response to landscape features may affect their ability to disperse over longer-distances, colonise new sites, and hence shift their ranges. Yet such information will be crucial for understanding the impacts of climate change on the distribution of biodiversity. The proposed work will provide the first investigation of how 'everyday' local flight behaviour in fragmented landscapes translates into longer-distance dispersal and colonisation success. We will focus on butterflies and collect new field data on butterfly flight path characteristics (displacement, speed of flight, directionality, etc) within breeding habitats, within non-breeding habitats, and at habitat/non-habitat patch boundaries. We will incorporate movement information and butterfly behaviour (ovipositing, nectaring, etc) into spatially-explicit dynamic models to estimate movements in 'real' study landscapes. We will test the reliability of our models by comparing modelled movements with those obtained from independent mark-recapture data for the same species and study landscapes. We will then use validated models to examine how variation in flight behaviour and availability of breeding habitat affects the probability of movement in study landscapes. Our models will also allow us to examine the effectiveness of conservation management plans to improve landscape connectivity (Impact Plan). The project will produce results of considerable practical value, as well as addressing fundamental questions about dispersal limits to species ranges. It will open up a new avenue of research on understanding and predicting the impacts of climate change on biodiversity. Conservation strategies must include adaptation strategies, but conservationists are uncertain about what to do. The proposed work will provide a concrete body of scientific evidence to inform this debate.