The ontogeny of echolocation in bottlenose dolphin (Tursiops truncatus) is little known and understood. Previous studies have demonstrated that neonatal dolphins can produce both whistles and burst-pulsed sounds just after birth and those early pulsed sounds are probably a precursor of echolocation click trains. The aim of this study is to investigate the development of echolocation signals, from early impulsive sounds to echolocation click trains, in a captive-born calf. A set of 113 impulsive sounds were collected from birth to the seventh postnatal week and 10 additional echolocation click trains were recorded when dolphin was 1 year old. For each sound we measured 5 acoustic parameters: click train duration (CTD), number of click per trains (NCT), minimum, maximum and mean click-repetition rate (CRR). CTD and NCT were found to increase with age and dolphin growth, while minimum, maximum, and mean CRR decreased starting from the second postnatal week. The first Head Scanning Movement was recorded 21 days after birth. Our data suggest that in bottlenose dolphin the early postnatal weeks are essential for the development of echolocation and the acoustic features of the echolocation click trains remain relatively stable from the seventh postnatal week up to the first year of life.
The ontogeny of echolocation signals in a captive-born bottlenose dolphin (Tursiops truncatus)
FAVARO, LIVIO;PESSANI, Daniela
2010-01-01
Abstract
The ontogeny of echolocation in bottlenose dolphin (Tursiops truncatus) is little known and understood. Previous studies have demonstrated that neonatal dolphins can produce both whistles and burst-pulsed sounds just after birth and those early pulsed sounds are probably a precursor of echolocation click trains. The aim of this study is to investigate the development of echolocation signals, from early impulsive sounds to echolocation click trains, in a captive-born calf. A set of 113 impulsive sounds were collected from birth to the seventh postnatal week and 10 additional echolocation click trains were recorded when dolphin was 1 year old. For each sound we measured 5 acoustic parameters: click train duration (CTD), number of click per trains (NCT), minimum, maximum and mean click-repetition rate (CRR). CTD and NCT were found to increase with age and dolphin growth, while minimum, maximum, and mean CRR decreased starting from the second postnatal week. The first Head Scanning Movement was recorded 21 days after birth. Our data suggest that in bottlenose dolphin the early postnatal weeks are essential for the development of echolocation and the acoustic features of the echolocation click trains remain relatively stable from the seventh postnatal week up to the first year of life.
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