Atividade bioacústica em ninhos de Eretmochelys imbricata (LINNAEUS, 1766) na Barreira do Inferno - RN

Abstract

Chelonians communicate mainly through smell and sight, but recent projects have shown a promising potential in the use of acoustic communication for this group, especially in regard to parental care. The research is an investigative analysis on the embryonic and hatchlings sound production in turtles (Eretmochelys imbricata), at Barreira do Inferno, Parnamirim - RN. For data collection, a TASCAM DR-40 recorder set to a sampling rate of 96kHz was used. We have analyzed 122 recordings with presence of eggs or eggs and hatchlings. In addition to the nests, hatchlings were recorded after nest emergence. Spectrographic analyses were performed on RAVEN Pro 1.5 software (Cornell Laboratory of Ornithology, Ithaca, NY). A specific window was used to compose each sound type spectrograms, namely Hamming, with FFT 256 for types 1 and 2 and 512 for types 3 and 4. Four acoustic patterns were performed for Eretmochelysimbricata nests and hatchlings in a total of 575 signs. The type 1 signal (N = 86) has an average duration of 0.0015 s, present up to 64 pulses and an average peak frequency of 759 Hz. Type 2 (N = 330) is a single pulse, which can appear in series of up to 25, with an average of 0.001s of duration of each pulse. The average peak frequency of Sound type 2 is 3055 Hz. The type 3 sound (N = 110) is tonal, formed by a single band, with frequency modulation and average duration of 0.01 s, the longest signals found. Type 4 (N = 49), have 2 to 5 harmonics and can have up to 6 inflection points, with a duration average of 0.07 s. Type 2 appeared on all contexts analyzed. Tonal sounds like types 3 and 4 were used with more frequency by hatchlings. Acoustic signals were detected from day 51 postnesting until nest emergence. The results showed that most emissions are produced overnight. It should be taken into account that the amount of recordings made in different contexts was not the same. The work is carried out in partnership with the TAMAR project and presents promising results on the acoustic communication of hatchlings and embryos of Eretmochelys imbricata.