Effectiveness of an acoustic wildlife warning device using natural calls to reduce the risk of train collisions with animals

The subject of study was the effectiveness of the UOZ-1 device - which emits the natural warning calls of animals - in protecting animals living near railway tracks. We performed the investigations in central Poland between 2008 and 2012 at two study sites along the E 20 line where the UOZ-1 devices had been installed. We used digital cameras to register animal activity 24 h a day, resulting in 2262 mammal observations (involving 2956 individuals). In 76% of the observations, no rail transport was observed. When a train did approach and acoustic signals were emitted, most of the wild mammals escaped (93-85% of cases, depending on the species). Regarding the most numerous species, the roe deer, the effectiveness of the device was tested by comparing the animals' reactions when a train approached with the device switched on or off. With sound signals emitted, animals escaped more often (84% vs. 68%), and their reaction to an oncoming train was 20 s faster. We found no proof that animals habituated to the warning signals because the proportion of roe deer that showed no reaction was similar in the first and last year of the study. There was also no difference between the reaction time to an oncoming train (on average 35 s). The results of this research indicate that the UOZ-1 is more effective in reducing the risk of train-animal collision, by prompting animals to leave the railway track faster and with greater frequency, than only the sound of an oncoming train.