Railway operations and the ban of killing protected animals – as in other fields, a balance between technical and economical, social and environmental aspects with regard to sustainability shall be achieved when parts of the transport infrastructure are upgraded or newly built. This leads to a special challenge when the objectives of moving more persons and goods by rail and those of protecting species are conflicting. The authors plead for an increased effort, in particular when it comes to the question of how to interpret and apply the ban on killing according to the German Federal Law on Nature Conservation to collisions with protected animals. Relevant considerations are being brought forward for discussion.