A central question in ecology involves understanding the processes underlying patterns in population abundance and the distribution of species at small and large spatial scales. The distribution of individuals of a species across a landscape may be influenced by both local factors, such as resource abundance; and by landscape-level factors, such as the size of habitat patches, connectivity between patches and the permeability of the matrix surrounding habitat patches, all of which influence the colonisation and extinction of local populations and the movement of individuals between populations. How these local and landscape-level factors affect the distribution of a species may vary widely between species, because the response of species to these ecological conditions may depend on species-specific traits, such as body size, behaviour and other functional traits. There is relatively little known about how ecological factors interact with functional traits to influence species distribution in a landscape. I investigated the ecological processes at local and landscape levels influencing population densities by taking a behavioural ecological approach and using butterflies as a model system. I also examined how functional traits affect the relationships between ecological factors and species distribution in a landscape. I first examined how resource dispersion, an important ecological condition affecting butterfly populations, affects key behavioural decisions of butterflies. Studying the behaviour of individuals allows us to link population patterns with underlying ecological and evolutionary processes. I describe how butterflies appear to respond to resource dispersion at both small and large spatial scales and to balance acquiring two distinct types of resources when making foraging and habitat-use decisions. I then examined how landscape-level factors, specifically patch size, connectivity and matrix permeability, affect butterfly populations. I tested whether the apparent response of a species to landscape-level factors was affected by species-specific traits, specifically whether it was a habitat generalist or specialist and how permeable the matrix was to it. Finally, I test and describe how diverse functional traits, including morphological, life-history and behavioural traits, affect relationships between landscape composition and population density patterns of butterflies.