The final call: evidence for signature whistle of dying common dolphin (Delphinus delphis) in Argentina, South America.

GISELA V GIARDINO; MARIA CERAULO; KARINA ALVAREZ; SALVATORE MAZZOLA; ELENA PAPALE; JUAN PABLO LOUREIRO; DIEGO H. RODRIGUEZ; GIUSEPPA BUSCAINO; MARTINA GREGORIETTI; SERGIO RODRÍGUEZ HEREDIA; RICARDO O. BASTIDA

Congreso; EFFECTS OF NOISE ON AQUATIC LIFE 2019; 2019

Signature whistles are stereotyped and individually distinctive acoustic signals emitted by T.truncatus in isolatedcaptive conditions. They are used as individual recognition signals, for maintaining group cohesion and duringstressful situations (Janik and Sayigh, 2010). However, little information was reported for other species(reviewed in Janik and Sayigh, 2013). Here, we tested the hypothesis of the occurrence of signature whistles inan isolated short-beaked common dolphin (Delphinus delphis) kept in a rehab circular tank (13m diameter,1.35m deep) at Mundo Marino Aquarium (San Clemente del Tuyú). The dolphin, an adult female, was foundashore in Villa Gesell, Argentina, on 19th January 2019. During its maintaining, a hydrophone (modelBenthowave BII-7017) with a flat sensitivity response of -174.5 (± 2) dB re V/µPa from 0.1 to 100 kHzconnected to digital analogical converter C5535 DSP (TMS320C5535), was deployed in the tank. Twenty-threehours of continuous recordings were collected, starting after 12 hours from the beginning of the dolphin´s rehabuntil their death for hepatitis. Data were visually screened and the number of whistles was noted. Six parameters(peak, maximum and minimum frequencies, duration, frequency contour and the number of harmonics) weremeasured from the recorded whistles by using Raven Pro (Cornell University). A total of 59 whistles wereanalyzed and only one type of frequency contour was detected (ascending-descending). They showed anaveraged peak frequency of 9. 04 ±2.33kHz; an averaged maximum frequency value of 13.28 ±1.81 and aminimum of kHz; a 5.99 ±1.58; the average duration was 0.72 ±0.29 seconds and harmonic´s number rangingfrom 1 to 4. The CV values of all parameters were lower than 0.4.The low variability of whistles parameters and the only whistle contour found in an isolated and stressed dolphinsupport the hypothesis that they produce signature whistles. It is the first evidence of the use of this signal inD.delphis in Southwester Ocean. Dolphins produce many non-stereotyped whistles but detecting the presence ofsignature whistles can provide us new info on socio-behavioral aspects and on the use of vocalizations. Our workis the first step to understanding Latin American common dolphin sound production, which the majority of theecological aspects are unknown.