Variation in the vocal behavior of common loons (Gavia immer): Insights from landscape-level recordings

Abstract

Animal signals play an important role in mate attraction and territory defense, and animals may benefit by adopting signaling strategies that maximize effective communication in the face of changing environmental conditions. In this study, a custom-designed microphone array was used to collect landscape-scale recordings of the acoustic signaling behavior of Common Loons (Gavia immer) along a 10-km transect spanning three lakes in eastern Ontario, Canada. Recordings were collected during the early part of the breeding season during two consecutive years (2008-2009). Analyses focused on understanding how the vocal output of Common Loons varied with time of day, time of year, and in response to variation in weather. Common Loons showed significant diel variation in vocal output, producing more wail, yodel, and tremolo calls at night than during the day. Common Loons showed significant seasonal variation in vocal output, producing fewer wail, yodel, and tremolo calls as the first month of the breeding season progressed. Common Loons showed significant differences in vocal behavior with changing weather conditions, producing more calls at cold temperatures, with low wind speed and air pressure, and when rain was light or absent. Microphone array recordings were used to estimate signal transmission properties of Common Loon vocalizations, demonstrating that wail, yodel, and tremolo calls transmit significantly farther at night than during the day. These results provide quantitative details of Common Loon vocal signaling strategies, revealing that this species calls when abiotic conditions are ideal for long-range signaling.