Modelling the broad-front migrations of European-African migratory birds
Dr Tom Mason1, Dr Philip Stephens1, Dr Christine Howard1, Dr Chris Hewison2, Dr Stephen Baillie2, Dr James Pearce-Higgins2, Professor Stephen Willis1
1Durham University, Durham, United Kingdom, 2British Trust for Ornithology, Thetford, United Kingdom
Globally, many migratory species are experiencing more rapid rates of population decline than their resident counterparts, yet little progress has been made in explaining these declines. Climate change has been implicated in some cases, but is occurring in parallel with extensive land-use changes in some areas, confounding inference. Crucially, migrants are susceptible to events occurring between migratory end points e.g., via phenological mismatching between arrival and key resources. However, most research into the impacts of changing conditions on migratory species has been static and correlative, failing to consider the processes occurring during the migratory journey itself. Here, we developed a general model for investigating the impacts of environmental change on the journeys of broad-front migrating songbirds between Europe and Africa. We used dynamic optimisation models to determine state-dependent optimal migration routes across landscapes with continually varying environmental characteristics. We parameterised our models based on flight theory – how far species of different aerodynamic form and mass can travel with a given fuel loads – and using data on fuel loads of migrants gathered through long-term bird ringing programmes. Finally, taking advantage of recent developments in geolocator technology, we validated simulated migration routes with data from geolocator studies of migratory passerines. Using our model we accurately simulated the routes, timings and energy profiles of a variety of species. It should now be possible to predict, for the first time, how future environmental change is likely to influence these migratory journeys, e.g., in terms of routes, timings, stop-over strategies, and mortality rates
Biography:
I am a conservation ecologist interested in how wild animal populations respond to changes in their environment, and how this information can be used to target conservation actions that maximise coexistence between humans and wildlife. I am currently a post-doc in the Conservation Ecology Group at Durham University in the United Kingdom, where I previously completed my PhD on the impacts of environmental change on alpine ungulates. In the period intervening these roles I carried out post-docs at Laval University in Canada and the University of Stirling in Scotland.