Flexible habitat use of stonechats Saxicola torquatus dealing with different anthropogenic novel environments

Organisms may respond to rapid human induced environmental changes by adapting their habitat requirements through behavioural flexibility. In human-modified landscapes from southern Belgium, recent management activities have generated structurally different and novel land-use types that are now occupied by a number of farmland bird species. However, as birds rely on environmental cues to select their habitat, they can be subject to maladaptive habitat selection if these cues become uncoupled from the underlying habitat quality. We therefore used the European Stonechat Saxicola torquatus as a model species to compare the relative attractiveness and breeding quality of the three main land-use types occupied by farmland birds (i.e. intensive grassland, Christmas tree plantations and clear-cut patches in plantation forests) in order to test whether habitat selection is adaptive in a changing landscape. Between 2014 and 2018, we examined the settlement pattern of territorial males to measure habitat preference and we recorded key parameters reflecting reproductive performances and individual survival to assess the quality of the three land-use types for the reproduction of the stonechats. Our results indicate that stonechats preferentially settle in clear-cut patches where they produce lower-quality offspring due to a gradual decrease of nestling body conditions during the breeding season. However, we found that this has no consequence on recruitment rates, because first-year survival was not related to nestling body conditions in our study system. As other parameters of reproductive performances, adult survival and first-year survival were similar between the three land-use types, we concluded that stonechats are capable of flexible habitat use and may find breeding opportunities of similar quality in the three land-use types although these strongly differ in terms of vegetation structure and management. Moreover, our results highlight the importance of measuring multiple fitness components to assess habitat quality in a comprehensive way.