Testing pole barriers as feasible mitigation measure to avoid bird vehicle collisions (BVC)

Abstract Numbers of bird vehicle collisions (BVCs) exceed several millions per year per country in Europe and North America. However, in contrast with the advances achieved in reducing road kills in mammals, few mitigation measures have been developed to reduce BVCs. Following this line, pole barriers have emerged as a cheap and effective measure to reduce bird mortality. We experimentally tested pole barriers in three different scenarios. First, we used trained raptors to test the effect of poles on their behaviour. We were unable to show that pole barrier was a good measure per se to prevent forest raptors crossing, but the results are promising when combining the poles with coloured flag elements. Second, we considered a corridor used for water birds to move from the feeding to the resting sites. The results showed that almost all birds (93.9%) shift the flight path to avoid poles. Only 17 birds of four different species out of 278 birds of 21 species flew throughout the poles. Therefore, the method may be suitable to reduce kills in those infrastructures affecting water birds and open area birds. Third, we attracted vultures to a feeding point where we tested the effect of a pole barrier. Overall 36% of the vultures that landed coming from the pole barrier direction and 24% of the vultures that took off using the same route flew through the pole barrier, suggesting that pole barriers are not so effective when feeding resources are conditioning the behaviour of birds. Our results show that pole barriers are effective tools to reduce BVC, mainly in open areas and close to water habitats. They also could reduce the likelihood of collision with scavengers and similar birds that are attracted by carcasses of previously killed animals.