There is an ongoing discussion on whether invasive cavity nesting birds restrict the breeding of native species by exploiting the limited resource (nest cavities) (exploitation competition) and by directly usurping cavities already occupied by the native species (interference competition). We are in a middle of a field study using a Before-After-Control-Impact (BACI) design using nest boxes to determine whether larger alien birds (common myna (Acridotheres tristis) limit the breeding of native species (great tits Parus major and house sparrows Passer domesticus). Our goal is to not only increase our scientific knowledge but also to propose management practices using nest-boxes in order to reduce competition between native cavity breeders and alien invasive birds.