On the origin of species on road warning signs

Abstract Collisions of vehicles with animals are an increasing problem, and due to the loss of animal, as well as human, life is an active topic in applied ecology. One of the best-known mitigation methods to avoid collisions is the provision of dedicated road warning signs. However, due to changes in landscape, in the densities of cars and animals, and to changes in animal and driver behaviour, there have been recent modifications to the style of signs and in the animal species featured on them. It is apparent that developments in the design of road signs, and the perception by humans that particular animals are important have changed in parallel. However, the situation regarding animal road signs varies between countries, and different legal systems, evolving from the 1968 Vienna Convention. We review the global situation of animal road warning signs, paying attention to the animals featured, and evaluate how the system works and what should be improved in the near future. We also provide some ideas on how a warning sign system can link to automatic driverless vehicles, which will probably develop much faster than we anticipate.