Abstract
A robust adaptation to environmental changes is vital for survival. Almost all living organisms have a circadian timing system that allows adjusting their physiology to cyclic variations in the surrounding environment. Among vertebrates, many birds are also seasonal species, adapting their physiology to annual changes in photoperiod (amplitude, length and duration). Tawny Owls (Strix aluco) are nocturnal birds of prey that use vocalization as their principal mechanism of communication. Diurnal and seasonal changes in vocalization have been described for several vocal species, including songbirds. Comparable studies are lacking for owls. In the present work, we show that male Tawny Owls present a periodic vocalization pattern in the seconds-to-minutes range that is subject to both daily (early vs. late night) and seasonal (spring vs. summer) rhythmicity. These novel theory-generating findings appear to extend the role of the circadian system in regulating temporal events in the seconds-to-minutes range to other species.
Highlights
Vocalization is a complex behavior and crucial in language evolution [1]
Our findings indicate that the temporal structure of Tawny Owl vocalizations—in the seconds-to-minutes range of interval timing—presents both daily and seasonal variation
The coefficient of variation (CV) for the 30 owls evaluated was higher for T2 than T1 (t29 = 7.211, p
Summary
Vocalization is a complex behavior and crucial in language evolution [1]. Birds are the most vocal group of animals other than humans and a few other primates. In songbirds (order Passeriformes, suborder oscines), neural vocal control is achieved by a chain of interconnected brain areas in the fore-, mid-, and hindbrain [2]. Vocal communication is of vital importance to non-oscine birds (owls, gulls, doves, etc.), which share with oscines a system of vocal control nuclei. Owls (order Strigiformes) rely on acoustic signals for long-distance communication and are very vocal in different contexts [3]. In songbirds (e.g., zebra finches, canaries), the motor pathway for song proceeds from the high vocal center (HVC) to the nucleus robustus arcopallialis (RA), which projects directly to vocal motoneurons (XIIts) and to respiratory premotor neurons in the nucleus retroambigualis (RAm) in the lower medulla.
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