The impact of climate change on habitat use: implications for predicting species' range changes

This proposal falls within the Ecology & Hydrology Funding Initiative. The lead CEH science programme is Biodiversity, but the proposal links strongly to the Environmental Informatics programme and the Climate Change cross-cutting theme There is an emerging consensus that the majority of animal species are responding to climate change, and that many species are at risk of extinction from climate warming. The main metrics of change reported in the scientific literature and in governmental reports are changes in the phenology (the timing of the life cycle, in relation to the changing seasons) and the distributions of species (many British species are moving northwards and to higher elevations). However, these are not the only ways that climate change affects species. The scientific literature and conservation organisations have largely ignored possible climate-driven changes in the habitat associations of species. The temperature conditions experienced by organisms vary between habitats, depending, for example, on the level of shading or protection from frost provided by the vegetation. Therefore, when the climate warms, particular habitats that were too cool in the past (e.g., shady woodlands) may now be warm enough to become occupied, and habitats that used to be favourable may become too hot (e.g., south-facing hillsides). So, the habitats that a species can occupy within a particular region may change as the climate warms and this may affect the patterns of distribution change; there is already evidence that at least a few species are changing their habitat associations in this way. The proposed work will provide the first systematic analysis of the impact of climate change on the habitat associations of an entire group of animals. We will quantify, for 57 species of British butterfly, the degree to which habitat use is modified by climate. We will determine how habitat use varies with geographical variation in the climate, and estimate for the first time how the habitats that species occupy have changed through time (since 1970), as the climate has warmed. The research programme will use the opportunity of climate change to test the ecological hypothesis that species become restricted to particular habitats at the edges of their geographic distributions, where the climate is generally unfavourable. Therefore, we predict that southern species (for which the climate is improving) will have shown increases in the variety of habitats they use over the last 35 years, whereas northern species (for which the climate is deteriorating) will have shown decreases in the range of habitats used. We will also collect new field data to examine relationships between habitat use and species survival in order to investigate the factors influencing species' habitat associations. The project will produce results of considerable practical value. It will open up a new avenue of research on the impacts of climate change on biodiversity. It will provide specific estimates of how the distributions of British butterflies are changing, and therefore whether additional habitats need to be protected, and whether the habitat management that is currently being applied is still appropriate. Conservation strategies must adapt to climate change, but conservationists are uncertain about what to do. The proposed work will provide a concrete body of scientific evidence to inform this debate.