It's time to go - Drivers and plasticity of migration phenology in a short-distance migratory ungulate

Files provided in the repository consist of two dataframes (.Rdata format) and two scripts (.R format) to perform analyses and making figures presented in the paper: "Drivers and plasticity of migration phenology in a short-distance migratory ungulate, the Alpine ibex Capra ibex"  

Abstract: 

Recurring events like migrations are an important part of the biological cycles of species. Understanding the factors influencing the timing of such events is crucial for determining how species face the pervasive consequences of climate change in highly seasonal environments. Relying on data from 406 GPS-collared Alpine ibex Capra ibex monitored across 17 populations, we investigated the environmental and individual drivers of short-distance migration in this emblematic mountain ungulate. Notably, we assessed how variations in the onset of spring and autumn affected the timing of migration and the extent to which ibex exhibited behavioral plasticity in their response. We found that vegetation phenology, including spring growth and autumn senescence, along with snow dynamics - snowmelt in spring, first snowfall in autumn - were the main drivers of the timing of migration.

In spring, ibex migration timing was synchronized with the peak of vegetation growth, but more in males than in females. Specifically, a shift of 10 days in vegetation growth peak delayed migration by 6.4 days for males and 2.7 days for females. This led to increased differences in migration timing between sexes when the vegetation growth peak occurred early or late in the season. In addition, ibex delayed migration timing when the length of growing season was longer and when the date of snowmelt on ibex summer range occurred later. Similarly, in autumn, prolonged vegetation senescence and delayed first snowfall led to later migration.

Overall, most of the response to inter-annual variations in vegetation and snow phenology could be explained by individual behavioral plasticity. Nonetheless, females appear to be less plastic than males in their timing of spring migration, likely due to the parturition period following migration forcing them to trade off foraging needs with predation risk. As the identified drivers of ibex migration are known to be and will continue to be largely impacted by climate change, the capacity of ibex to respond to such rapid changes could differ between sexes.