Postnatal Development of Echolocation Abilities in a Bottlenose Dolphin (Tursiops truncatus): Temporal Organization

Abstract

In spite of all the information available on adult bottlenose dolphin (Tursiops truncatus) biosonar, the ontogeny of its echolocation abilities has been investigated very little. Earlier studies have reported that neonatal dolphins can produce both whistles and burst-pulsed sounds just after birth and that early-pulsed sounds are probably a precursor of echolocation click trains. The aim of this research is to investigate the development of echolocation signals in a captive calf, born in the facilities of the Acquario di Genova. A set of 81 impulsive sounds were collected from birth to the seventh postnatal week and six additional echolocation click trains were recorded when the dolphin was 1 year old. Moreover, behavioral observations, concurring with sound production, were carried out by means of a video camera. For each sound we measured five acoustic parameters: click train duration (CTD), number of clicks per train, minimum, maximum, and mean click repetition rate (CRR). CTD and number of clicks per train were found to increase with age. Maximum and mean CRR followed a decreasing trend with dolphin growth starting from the second postnatal week. The calf's first head scanning movement was recorded 21 days after birth. Our data suggest that in the bottlenose dolphin the early postnatal weeks are essential for the development of echolocation abilities and that the temporal features of the echolocation click trains remain relatively stable from the seventh postnatal week up to the first year of life.

Postnatal development of franciscana's (Pontoporia blainvillei) biosonar relevant structures with potential implications for function, life history, and bycatch

“…Although routine modern imaging techniques are unable to detect delicate structures in the tympano-periotic complex and the ear ossicles (malleus, incus, and stapes) (Ketten 1994, Gutstein et al 2014 it is remarkable that the neonate ear complex volume and anatomy matches the adult shape and volume more than the rest of the 1206 head. Recent findings demonstrate that newborn bottlenose dolphins are capable of whistle learning (Killebrew et al 2001, Morisaka et al 2005, Favaro et al 2013, and that the first pulse trains can be recorded on the 14th day of life (Favaro et al 2013). Our anatomical data suggest that the sound generating system and the auditory sense may be functional at birth, since the location of the mandibular fat bodies relative to the mandible foramen in the neonates supports the function proposed by Norris (1968).…”

“…), and that the first pulse trains can be recorded on the 14th day of life (Favaro et al . ). Our anatomical data suggest that the sound generating system and the auditory sense may be functional at birth, since the location of the mandibular fat bodies relative to the mandible foramen in the neonates supports the function proposed by Norris ().…”

“…, Favaro et al . ), and that the first pulse trains can be recorded on the 14th day of life (Favaro et al . ).…”

Ontogenetic development and sexual dimorphism of franciscana dolphin skull: A 3D geometric morphometric approach

“…In this sense, the early development of these bones in P. blainvillei may be associated with the precocious development of the sound production apparatus. Previous studies performed on odontocetes (e.g., Hendry, ; Li et al, ; Favaro et al, ) indicate that sound emissions in some species ( Tursiops truncatus and Neophocaena phocaenoides asiaeorientalis ), starts at 22 days of age or earlier. Although there is no data about the age at which echolocation actually begins in P. blainvillei , the early development of such capacity is probably a characteristic widespread in odontocete cetaceans (e.g., Yurick and Gaskin, ); the proportionally wider premaxillary bones observed in immature franciscana dolphins (Fig.…”

Pectoral Fin Contact Between Dolphin Dyads at Zoo Duisburg, with Comparison to Other Dolphin Study Populations

“…These studies have focused on stress (Waples & Gales, 2002); mother-calf interactions (Gubbins et al, 1999) and calf development (Fellner et al, 2012), including the development of whistle (Fripp & Tyack, 2008) and echolocation production (Favaro et al, 2013); and dolphin/human interactions, particularly during interactive programs (Frohoff & Packard, 1995). Studies investigating social, affiliative, and communicative behavior of captive dolphins are scarce (e.g., Tamaki et al, 2006;Dudzinski et al, 2010); and research that compares wild and captive dolphin social behavior are even more uncommon (Caldwell et al, 1965;Brown et al, 1966;Mann & Smuts, 1999;Dudzinski et al, 2010;Greene et al, 2011).…”