Red squirrels are among the most commonly sighted wildlife in European big cities such as Berlin. However, their habitats are more reminiscent of a patchwork quilt full of challenges, a team of scientists led by the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) found out, with the help of computer models and red squirrel sightings by citizen scientists. The models link sightings to numerous environmental parameters and thus become important tools for urban planning, as they identify areas where ecological corridors are missing that could connect fragmented habitats.