Migratory decisions in a changing world: mechanisms and drivers of changing migratory behaviour

Evidence is growing that the migration behaviour of many species is changing in response to environmental change, with resident individuals being reported in previously wholly migratory populations and increases in the proportion of non-migrants being reported for a range of bird species in Europe. These rapid changes in migratory behaviour provide an opportunity to identify the control mechanisms underpinning these complex and highly evolved behaviours, and thus their capacity to adapt to changing environmental conditions. This project will fill a major current gap in migration science, by identifying the mechanisms influencing demography and behaviour of migratory and non-migratory individuals, and it will contribute to the understanding of the capacity for migratory behaviour to respond to rapid environmental change. As many migratory bird species are currently suffering rapid population declines, and many migratory species are hunted in Southern Europe, understanding these mechanisms is necessary to allow predictions of future changes in migratory bird populations, which is key to improve the effectiveness of protected area networks across Europe and Africa, and to reduce potential conflicts between migratory species and human activities.

The capacity for migratory behaviour to adapt to environmental changes will be influenced by whether individuals can alter their migration strategies, or whether changes in relative fitness are required to alter the proportions of differing strategies in a population. Facultative changes in individual migration strategies are likely to allow more rapid responses to environmental change, but such control mechanisms may be influenced by social or environmental factors. Identifying the control mechanisms influencing changes in migration systems therefore requires a study system in which individual migration strategies, their consistency and demographic consequences can all be quantified.

The proposed study involves a species of migratory bird for which there is annual variation in migration and for which individuals have been tracked on their migratory journeys: lesser kestrels (Falco naumanni). We aim to identify the mechanisms enabling changes in migratory behaviour by exploring the influence of social relationships, behavioural adaptations and heritability on individual migration strategies. We will incorporate this information in population models in order to explore the relative importance of individual plasticity in behaviour and demographic variation in altering rates and patterns of change in migratory behaviour, and the potential influence of future changes in climatic conditions and resource availability.

This project will produce results of considerable practical value, as well as addressing fundamental questions about the mechanisms underlying changes in migratory behaviour. Understanding the capacity for migratory behaviour to adapt to changing environmental conditions is key to predicting future changes in migratory populations, identifying and implementing appropriate conservation strategies, and exploring the role of these changes in the ongoing population declines of many Afro-Palearctic migratory bird species.

Policy-makers and practitioners urgently want to include environmental change adaptation strategies for biodiversity in their conservation and land-management policies. Changing behaviour of migratory species of birds poses several challenges: for conservation biologists interested in the protection of endangered species it will be important to be able to predict how these changes will affect the conservation status of species and how distribution changes may be included in the design of protected areas for conservation; for land managers interested in maximizing agricultural outputs, it will be important to understand which new species may occur in their lands and how population sizes will change, in order to implement management techniques that minimize potential conflicts with wildlife. In Southern European countries many migratory species are hunted, and current changes in the migratory behaviour of species are likely to increase the exposure of migratory species to hunting pressure, thus understanding the consequences of changing migratory behaviour at the population level will be essential for sustainable exploitation of hunted migratory species. Developing a strong evidence base for predictions of future changes in migratory behaviour in response to environmental change will be key in enabling the development of conservation and management decisions and adaptation measures. Our main research programme will investigate how environmental change may influence individual migratory decisions and demographic changes within migratory populations. In addition to supporting the development of conservation strategies for migratory species, our study will: (1) stimulate public involvement in the conservation of endangered species through the development of a website where the general public and visitors of LPN's Environmental Education Centre can see the activity inside lesser kestrel nest sites during the whole breeding season (2) train volunteers to identify lesser kestrels and to collaborate in national lesser kestrel census; (3) develop an education kit for school children to engage with the importance of conservation of migratory species and the need for evidence-based conservation. The main findings will be published in peer reviewed journals, on the web and, in conservation reports to ensure they will reach all stakeholders and the wider public.