Movement, Abundance, Distribution
- Published: 21 March 2022
Université Savoie Mont-Blanc
Bureau 109, 1ème étage
Superviseurs: Aurélie Coulon (CEFE) et Anne Loison (LECA)
Projet / Project:
Seasonal partial migration in Alpine Ibex : drivers, determinants and plasticity of phenology, migration corridors, and connectivity under global environmental changes
Migration refers to an animal’s movement between distinct seasonal ranges to benefit from better resources and/or conditions. Partial migration occurs when only a part of the population migrates, the rest being residents. Migration represents energetic costs and is risky for individuals that travel through unfamiliar habitats. This process has major impacts not only on individuals, populations and migrant species themselves but also on their ecosystems. Within wild ungulates, partial seasonal migration is common. Depending on the season, those herbivores can surf “the green wave” by following the gradient of emerging vegetation, or they can avoid the rarefaction of resources and harsh weathers and reduce the risk of predation.
Though less known than African or North American ungulate migrations, migrations also occur in Europe and France. They are particularly remarkable in mountainous habitats, where the Alpine ibex (Capra ibex) can travel dozens of kilometers in steep and snowy habitats. This emblematic alpine species, now protected, went nearly extinct during the 19th century and is now widespread thanks to a vast reintroduction program. Despite the 50 000 individuals and 178 populations across the Alps, the species conservation status remains worrying because of the low genetic diversity and its poor colonization capacity, which impedes connections between populations. A better understanding of ibex migration is crucial for its conservation. Indeed, spring migration and its synchrony with vegetation phenology may play a key role in the species demography which depends on individual capacity to access good quality and abundant food resources during summer when they can constitute fat reserves to survive winter conditions. This spring migration is even more determining for females because migration occurs a few days or weeks before parturition and the breeding period when lactating requires an increase energetic demand. Climate warming is exacerbated in mountainous habitats (+2°C since the 19th century, 2 to 3 times faster than the world trend), with significant consequences on vegetation phenology. Finally, autumn migration precedes rut, therefore migratory movements influence gene flows within populations. In this context, the emergence of large infrastructure projects with the multiplication and diversification of recreative activities throughout the year may impede migratory movements. Identifying which landscape features ibex use within their corridors is essential to assess the potential impacts of such projects, consider the protection of sensitive areas used during migration, and associate human development and biodiversity. Thus, there is a need to better understand this singular phenomenon, the determinants of its phenology, landscape features used by alpine ibex during migration, and assess its demographic, genetic, sanitary, and ecosystemic consequences.
The main goals of my project are:
1 – Using GPS data collected over the entire Alps, I will describe the phenology of this migration, understand its determinants and drivers, and assess its plasticity and threats caused by global warming and advancing vegetation phenology.
2 – Identify migration corridors, understand which features ibex look for when moving, assess the threats caused by fragmentation due to linear infrastructures, and measure migratory connectivity inside populations and over the Alps.
3 – Invest the role of social behavior, cultural transmission, learning and memory in used migration corridors and the plasticity of these corridors.
4 – Evaluate the costs and benefits associated with migration, the link between this tradeoff and the proportion of migrants within studied populations and the flexibility in the choice to whether migrate or not.