Authors: Hintsanen, Leena; Lehikoinen, Aleksi;Marjakangas, Emma-Liina;

Conservation of biodiversity relies heavily on protected areas but their role and effectiveness under warming climate is still debated. We estimated the climate-driven changes in avian community structure inside and outside of protected areas. To study community changes, we used large-scale survey data of breeding birds from Canada. To describe the temperature preference of bird communities, we calculated the community temperature index (CTI) annually for each bird community inside and outside protected areas. A high CTI value represents a community dominated by warm-dwelling species. We modelled temporal changes in CTI as a function of protection status using linear mixed effect models. In addition, we studied which species contributed most to the temporal changes of bird communities. Our results show that CTI is lower inside protected areas. However, against our hypothesis, CTI increased faster inside protected areas compared to outside areas, and the warm-dwelling species contributed most to CTI change within protected areas. These results highlight the ubiquitous impacts of climate change. Currently, protected areas can aid cold-dwelling species by providing suitable habitats, but the community compositions inside protected areas quickly approach those outside the protected areas, potentially erasing the conservation benefits of protected areas for cold-dwelling species.