Disentangling the effects of genetic and environmental factors on movement behaviour

Individual variability in animal movement behaviour is well documented for many species. However, it remains unclear whether this variability reflects genetic variation, environmental variation, or a combination of the two. Here, we conduct a cross-fostering experiment with the aim of investigating the role of these two components in movement patterns during the post-fledging dependence period and early natal dispersal of 21 eagle owls Bubo bubo. Our experiment showed that cross-fostering did not influence any of the movement parameters considered. Movement parameters were, however, affected by the age and sex of the owlets. We therefore suggest that individual variability and family resemblance in movement behaviour during the post-fledging dependence period and early natal dispersal might not be due to the common genetic origin of siblings, but rather that it originates from factors related to the rearing environment.