Acoustic parameters of Phyllodytes luteolus in conditions of low and high noise from vehicle traffic

Field activities were carried at five sampling sites in the municipality of Ilhéus, Bahia, Brazil. All areas have bromeliads used as reproductive sites by Phyllodytes luteolus. Three sites with the presence of vehicle traffic noise were located next to the BA-001 highway (between 3 and 10 meters away from the highway), in the stretches between Olivença and Acuípe villages, in the municipality of Ilhéus. The sampling sites were defined as Natural (no traffic noise) or Highways (with traffic noise). For each recorded individual, we obtained the social situation in which the male was inserted, being: with chorus (four or more conspecific individuals in vocalization activity within a three-meter radius – CC) or without chorus (four or less conspecific individuals vocalizing within a radius of three meters – SC). Males of Phyllodytes luteolus in vocalization activity were found through visual and auditory searches between 19:00 and 24:00 hrs. After viewing the male, the advertisement calls were recorded using a Sennheiser ME66 directional microphone coupled to a Marantz PMD660 hand recorder at a distance of 0.5 meters from the vocalizing male. As P. luteolus males have a long silent interval between calls, each male was recorded for ten minutes, in order to obtain as many calls as possible. The acoustic parameters were extracted using Raven Pro 1.6 software. Three to five calls were analyzed for each individual. The acoustic parameters extracted were: call duration (s), number of notes, number of pulses per call, pulse duration (s), rise time (s), interval between calls (s), repetition rate (calls/min.) and dominant frequency (Hz). The acoustic terminologies followed Köhler et al. (2017). The sound pressure level (SPL; intensity) was obtained for three to five advertisement calls from each individual using a Minipa MSL-1301 decibel meter (range: 30-130dB; 125ms, fast) positioned directly in front of and 0.5 meters away from the male in vocalization activity. Shortly after the recordings were finished, the males were captured for measurement of the snout-vent length (SVL) with a Western caliper (accuracy of 0.1 mm). Air temperature and humidity were recorded using a thermo-hygrometer (TechnoLine WS 9440, 0ºC precision).