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Greater Yellowstone Ecosystem Report

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The study of animal communication has been dominated by a focus on signal types that are easily recognized and quantified by human observers. This approach has inevitably limited our ability to identify cryptic signals such as low-amplitude vocalizations and signals that transmit beyond the range of our sensory system, such as most olfactory signals. Only recently with the development of new technologies and less biased sampling techniques have we begun to unravel the importance and function of these non-traditional signal types. Here we report the results of two experiments focusing on poorly studied signals using a common songbird, the dark-eyed junco. We investigated the effect of low-amplitude song on male physiology and the occurrence of bill-wiping behavior during courtship and aggressive interactions. Preliminary results suggest that males do not alter their plasma testosterone or corticosterone levels in response to a song playback of high-amplitude or low-amplitude song, indicating that a stronger stimulus may be necessary to affect circulating hormones. Males that received intrusions of a live male or female conspecific performed significantly more bill-wiping in response to the female conspecific, suggesting that bill-wiping may be an important and overlooked courtship signal in this species.