| Abstrakt: |
Many animals produce long-distance acoustic signals to mediate a variety of social interactions, and the efficacy of transmission depends in part on environmental attenuation. Vocalizing from positions that optimize transmission is one key solution to minimizing attenuation, though few studies assess the magnitude of this effect in relation to receiver position. In this study, we assessed how transmission of high-frequency vocalizations produced by pinyon mice (Peromyscus truei) varied based on the position of senders and receivers. Pinyon mice are semi-arboreal rodents that produce sustained vocalizations to advertise to conspecifics. Synthesized signals derived from a population-sample-average of fundamental frequency, duration, and amplitude were broadcast and recorded at different heights (0, 1, and 2 m) and distances (1, 2, 4, and 8 m) in a full factorial design to mimic hypothetical senders and receivers. We also measured receiver hearing sensitivity using auditory brainstem responses (ABR) to quantify the audible distance (active space) of vocalizations at different heights. Vocalizations showed less attenuation when emitted and received from an elevation compared to the ground if the signal was received at least 4 m from the sender. Vocalizations emitted from a 1 m height had an approximately 3 times greater audible distance compared to the ground. Additionally, less attenuation occurred when both senders and receivers were elevated at the same height and when receivers were elevated, regardless of sender height. Our results highlight the importance of considering receiver position in animal communication, especially when senders produce highly directional signals. Significance statement: Vocalizing animals often position themselves in locations that maximize sound transmission. However, the magnitude of this effect is not often quantified, especially in relation to the position of intended receivers. In this study, we combined acoustic recording, hearing experiments, and modelling of sound attenuation to quantify how sending and receiving vocalizations from trees impacts sound transmission in a semi-arboreal mouse. We found that vocalizations produced from 1 m above the ground could be heard by receivers at 3 times the distance compared to ground level. We also found that no matter the sender position, receivers benefitted from being at elevated positions. Finally, we found that the least attenuation occurred when senders and receivers were elevated at the same height. Our results highlight the importance of considering receiver position in animal communication, especially when senders produce highly directional signals. [ABSTRACT FROM AUTHOR] |
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