Amphibious hearing in a diving bird, the great cormorant (Phalacrocorax carbo sinensis).
J Exp Biol
; 223(Pt 6)2020 03 17.
Article
em En
| MEDLINE
| ID: mdl-32098879
ABSTRACT
Diving birds can spend several minutes underwater during pursuit-dive foraging. To find and capture prey, such as fish and squid, they probably need several senses in addition to vision. Cormorants, very efficient predators of fish, have unexpectedly low visual acuity underwater. So, underwater hearing may be an important sense, as for other diving animals. We measured auditory thresholds and eardrum vibrations in air and underwater of the great cormorant (Phalacrocorax carbo sinensis). Wild-caught cormorant fledglings were anaesthetized, and their auditory brainstem response (ABR) and eardrum vibrations to clicks and tone bursts were measured, first in an anechoic box in air and then in a large water-filled tank, with their head and ears submerged 10â
cm below the surface. Both the ABR waveshape and latency, as well as the ABR threshold, measured in units of sound pressure, were similar in air and water. The best average sound pressure sensitivity was found at 1â
kHz, both in air (53â
dB re. 20â
µPa) and underwater (58â
dB re. 20â
µPa). When thresholds were compared in units of intensity, however, the sensitivity underwater was higher than in air. Eardrum vibration amplitude in both media reflected the ABR threshold curves. These results suggest that cormorants have in-air hearing abilities comparable to those of similar-sized diving birds, and that their underwater hearing sensitivity is at least as good as their aerial sensitivity. This, together with the morphology of the outer ear (collapsible meatus) and middle ear (thickened eardrum), suggests that cormorants may have anatomical and physiological adaptations for amphibious hearing.
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Texto completo:
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Base de dados:
MEDLINE
Assunto principal:
Audição
/
Testes Auditivos
Limite:
Animals
Idioma:
En
Ano de publicação:
2020
Tipo de documento:
Article