Integrating individual movement behaviour into population ecology

The project aims at a better understanding of the population ecology of long lived bird species by recording individual movement behaviours and link them with habitat characteristics at one hand and fitness measures at the other hand. It includes the fitness and demographic consequences of differential food availability affected by land use, climate change, and anthropogenic feedings, the mechanisms underlying partial migration behaviour, the drivers of natal dispersal and patterns and causes of mortality.

Since 2015, we tagged 484 juveniles and 78 adult birds with solarpowered GPS transmitters in the Cantons of Fribourg and Bern, Switzerland, generating longterm information on movement and mortality patterns. Extensive territory mapping and nest controls have been done. Nest cameras recorded incubation behaviour, food deliveries and survival of the nestlings. We conducted food supplementation experiments during different seasons to identify the effect of food availability and anthropogenic feeding on reproduction, survival, natal dispersal and migration behaviour.

Given the significant fraction of Europe’s Red Kites occurring in Switzerland, the country has a large responsibility for the species. Our project will identify the drivers shaping the population dynamics of Red Kites which is pivotal for its conservation at the European distributional scale. The unprecedented sample of GPS tracked individuals combined with an experimental approach will enhance our understanding of the causes of the population increase in Switzerland in particular, and the mechanisms of natal dispersal in long-lived bird species and of partial migration in general.

Our analyses showed a high availability of anthropogenic food in the study area for facultative scavengers like the red kite. High food availability and early position in the hatching rank were associated with reduced stress levels, increased survival, early departure from the parental home-range, changed range use after independence, and higher probability of shifting from migrant to resident strategy. Habitat preferences were stronger for the settlement phase than during prospecting. Migratory behaviour, reproduction and survival all showed clear age and space patterns.

We are engaged in a large network of collaborators across Europe to study population ecology, movement ecology and population genetics of Red Kites throughout its global range. The collaborative project will help elucidating the phylogeographic history, demographic processes, and migration at a European scale.

• Dr. Adrian Aebischer
• AG Naturschutz, Universität Marburg
• Anne-Katleen Malchov und Damaris Zurrel, Universität Potsdam
• Rainer Raab, Technisches Büro für Biologie, Deutsch-Wagram, Österreich
• Eurokite

• Schweizerischer Nationalfonds
• Stiftung Yvonne Jacob