Railway noise and long-distance calls of free-living maned wolves in Ecological Station of Itirapina, São Paulo, Brazil

Abstract

For the present study, we evaluated the long-distance vocalization of free-living maned wolves of the Ecological Station of Itirapina, São Paulo, Brazil. This population has been exposed to railway noise for at least 100 years, since the railroad activities, in 1916. For the present study, we aim to investigate long-distance calls of maned wolves in this area, verifying the presence and absence of calls during the railway noise. For six months, between February and December 2016, we collect data using passive acoustic monitoring systems. The evaluation data set comprised 600 h of file recordings. The measurement of sound activity used in this study was the occurrence of long-distance calls sequences and railway noise. To assess the variation of the occurrence in long-distance calls and railway noise, hourly calling rates were calculated. The railway noise was most frequent between 9 p.m. and 10 p.m. UTC. The time distribution of long-distance calls and railway noise varied between the 12 hours of record with more vocalizations from 12 a.m. to 3 a.m. UTC. Our results provided cues of how a vocally active mammal species may communicate in a noisy environment.