From virtue to sin: Is the installation of bat boxes an effective conservation measure or a potential pitfall for vulnerable bat species?

Bat boxes are a key element in bat conservation policies being very popular. However, it is a biased action that is only favourable for a few bat species. In this manuscript, we hypothesize that the installation of these elements and an extensive proliferation of them could threaten other bat species more vulnerable due to the niche competition. For this, we calculated the overlapping degree between the bat species that use bat boxes and those that do not, specifically: (1) To determine the favourability area of these bat species through habitat suitability models in Iberian Peninsula; (2) To compare the overlapping degree between both bat groups; (3) To elaborate optimal maps for the installation of bat boxes through optimization algorithm; and (4) To discuss the implications for the conservation of this action. Our results showed that the overlapping between bat boxes users and the other species is high (mean 76.3 %) and there are areas where a bat boxes not user species could compete with at least 9 bat boxes user species. Therefore, the installation of bat boxes could be counterproductive, and we should focus on other conservation actions. We used an optimization algorithm to find out those areas where it is not recommendable to install them and developed a flowchart to evaluate its installation in an area. In conclusion, our study highlights that conservation actions on some occasions could be negative or be a pitfall for themselves, and it is necessary to discuss the effectiveness of certain measures for bat conservation.