Hearing in helmeted guineafowl (Numida meleagris): audiogram from 2Hz to 10kHz and localization acuity for brief noise bursts.

Abstract

Behavioral hearing thresholds and noise localization acuity were determined using a conditioned avoidance/suppression procedure for three Helmeted guineafowl (Numida meleagris). The guineafowl responded to frequencies as low as 2Hz at 82.5dB SPL, and as high as 8kHz at 84.5dB SPL.At a level of 60dB SPL, their hearing range spanned 8.12 octaves (24.6Hz-6.86kHz). Like most birds, they do not hear sounds above 8kHz. However, the guineafowl demonstrated good low-frequency hearing (frequencies below 32Hz), showing thresholds that are more sensitive than both the peafowl and pigeon, both of which hear infrasound. It thus appears that infrasound perception may be more common than previously thought and may have implications for species that inhabit areas with wind energy facilities. The guineafowls' minimum audible angle for a 100-ms broadband noise burst was 13.8 °, at the median for birds and near the mean for mammals. Unlike in mammals, the small sample of bird species and limited representation of lifestyles do not yet allow for meaningful interpretations of the selective pressures or mechanisms that underlie their abilities to locate sound sources.