Effect of predation risk, body size, and habitat characteristics on emigration decisions in mallards

Understanding the processes underlying emigrating behavior is fundamental to better understand animal dispersal. Because of the difficulties involved in carrying out controlled manipulation of the proximate drivers of emigration over large spatial scales, results from laboratory or small field enclosures suitable for small-bodied species remains to be validated in natural habitats. We investigate whether emigration is driven either by intraspecific competition or resulted from hunting-risk avoidance and assessed the effect of phenotypic variation on individual decisions. We made use of a quasi-experimental situation by using hunting recoveries of mallards (Anas platyrhynchos) released as ducklings in a fragmented landscape managed for duck hunting. Our results suggest an indirect effect of hunting on emigration. Body size plays a major role in modulating individual emigrating decisions, with small-bodied individuals emigrating more to escape from high levels of predation pressure while larger bodied individuals being more vulnerable to predation.