Meeting Abstract

84.1  Friday, Jan. 6  Auditory Brainstem Response in Sea Ducks and Diving Ducks THERRIEN, Sara*; CARR, Catherine; WELLS-BERLIN, Alicia; University of Maryland, College Park; University of Maryland, College Park; U.S. Geological Survey, Patuxent Wildlife Research Center

The Auditory Brainstem Response (ABR) is a valuable physiological technique used to describe an animal’s auditory sensitivity in a minimally invasive and time-efficient manner. The ABR is a scalp-recorded potential resulting from synchronized neural discharge (population response) following an auditory stimulus. This synchronized response is manifested as a series of four or more waves occurring within the first 10 ms following stimulation and represents the progressive propagation of auditory neural activity through the ascending auditory pathway. In this study, we have used the ABR to test hearing in one species of diving duck (Lesser Scaup, Aythya affinis), as well as several species of sea duck, including Long-tailed ducks (Clangula hyemalis), Surf Scoters (Melanitta perspicillata), White-Winged Scoters (Melanitta fusca), Black Scoters (Melanitta americana), and Harlequin ducks (Histrionicus histrionicus). The typical duck ABR waveform showed two to three prominent peaks. Peak amplitude of the response increased and peak latency of the response decreased with increasing stimulus sound pressure level (SPL). Threshold was defined as 2.5 dB below the lowest SPL that evoked a visual response (visual detection method). The best range of hearing for all six species was from 1000 Hz to 4000 Hz, with sensitivity peaking between 1500 Hz and 3000 Hz. Both the waveform morphology and response characteristics of the peaks to changing stimulus intensity are similar to those found in other avian species, such as screech owls (Megascops asio) and budgerigars (Melopsittacus undulatus). These results represent the first measurement of auditory sensitivity of any sea duck or diving duck.