Assessment of Ecological Bridges at Wildlife Crossings in Türkiye: A Case Study of Wild Boar Crossings on the Izmir-Çeşme Motorway

Abstract

In this study, the use of an ecological bridge installed as a wildlife overpass and constructed in the Zeytinler neighborhood in 2020 was analyzed as a mitigating factor in wild-boar–vehicle collisions (WVCs) on the Izmir-Çeşme motorway. In this context, this study aimed to assess the use of the Zeytinler Ecological Bridge by wild boars (Sus scrofa Linnaeus, 1758). To this end, wildlife crossings were monitored, analyzed, and modeled with Bayesian networks. Between August 2020 and December 2022, a total of 686 instances of movement were observed among six medium to large wild mammal species. Wild boars accounted for approximately 87.5% of the recorded wildlife crossings, with foxes comprising 10%. The findings showed that the highest frequency of wildlife crossings occurred during the autumn season, particularly between 22:00 (10 p.m.) and 02:00 (2 a.m.), coinciding with the Waxing Gibbous and Waxing Crescent phases of the moon. The model outcomes highlighted that during the autumn season with a full pond, wild boar crossings increased by one and a half times in comparison to regular herd crossings. Throughout the observation period, there were no instances of wild boar fatalities subsequent to the completion of the bridge.