Bart Nolet

1 INTRODUCTION Dispersal is a widespread demographic process that can be found across all taxa, affecting population dynamics, spatial distribution and the degree of genetic variation between populations (Greenwood, 1980). At the individual level, dispersal is often considered to be a strategy to improve breeding conditions by reducing competition for mates or resources and providing opportunities to find new sites or mates (Lagrange et al., 2014; Nevoux et al., 2013).

1 INTRODUCTION Environmental seasonality increases with latitude and results in spatiotemporal variation in resource availability. In response, animals have evolved various life-history strategies to cope with seasonality. Migration is a striking example of a life-history tactic that enables animals to exploit seasonally occurring food peaks, while avoiding periods of scarcity (Holt & Fryxell, 2011; Newton, 2008).

1 INTRODUCTION Climate warming threatens the persistence of species and ecosystems across the globe (Parmesan, 2006; Urban, 2015; Walther et al., 2002; Wong & Candolin, 2015) and migratory animals may be especially vulnerable since they inhabit at least two different geographical areas where the extent and rate of change can differ (Culp et al., 2017; La Sorte et al., 2019; Runge et al., 2014).