Flexible habitat use of an open-habitat bird species in a farmland-woodland landscape of southern Belgium

Behavioural flexibility is the first way for organisms to respond to anthropogenic modifications of the environment. In the Belgian Ardenne, harvesting of plantation forests have created large clear-cut patches, while in the same time, production of Christmas trees has massively developed in farmland. These novel habitats were colonized by a number of bird species formerly associated to grassland in this landscape. However, as birds rely on environmental cues for habitat selection, their choice may be maladaptive if the cues become uncoupled from the underlying habitat quality. Therefore, in order to test if habitat selection is adaptive in this changing landscape, we compared the attractiveness and breeding quality of clear-cut patches, Christmas tree plantations and grassland for the European Stonechat Saxicola torquatus, used as a model species between 2014 and 2018.
Examination of the settlement pattern of territorial males indicated that stonechats preferentially settle in clear-cut patches, where their fitness (reproductive performances and survival) was not found to be higher. They produced there lower-quality offspring due to a gradual decrease of nestling body conditions during the breeding season, but we failed to demonstrate that this had a negative consequence on first-year survival probabilities and thus on parental fitness. As other parameters of reproductive performances, adult survival and first-year survival were similar between the three habitats, we concluded that clear-cut patches, Christmas tree plantations and grassland may provide breeding opportunities of similar quality to stonechats, although they strongly differ in terms of vegetation structure and management.