(2) Dos de las características derivadas de las alas que aparentemente evolucionaron para suprimir el sonido del vuelo son los flecos del vexilo y la felpa dorsal de las alas de las lechuzas. La evidencia actual favorece levemente la hipótesis del auto-enmascaramiento, pero éste tema permanece irresuelto. Proponemos y exploramos posibles respuestas a tres preguntas sobre la evolución y ecología del vuelo silencioso en lechuzas: (1) ¿Las lechuzas vuelan silenciosamente por sigilo o para reducir el auto-enmascaramiento?. Owl flight may not be the best (and certainly, not the only) model for "bio-inspiration" of silent flight. ![]() This implies that bats may be an overlooked model for silent flight. This hypothesis suggests a new perspective: rather than regarding owls as silent, perhaps it is bird flight that is loud. We hypothesize that bird flight is noisy because wing feathers are intrinsically predisposed to rub and make frictional noise. (3) Have other animals also evolved silent flight? Wing features in nightbirds (nocturnal members of Caprimulgiformes) suggest that they may have independently evolved to fly in relative silence, as have more than one diurnal hawk (Accipitriformes). Several lines of evidence instead support the hypothesis that the velvet and fringe reduce frictional sound, including: the anatomical location of the fringe and velvet, which is best developed in wing and tail regions prone to rubbing, rather than in areas exposed to airflow the acoustic signature of rubbing, which is broadband and includes ultrasound, is present in the flight of other birds but not owls and the apparent relationship between the velvet and friction barbules found on the remiges of other birds. Do these two features suppress aerodynamic noise (sounds generated by airflow), or do they instead reduce structural noise, such as frictional sounds of feathers rubbing during flight? The aerodynamic noise hypothesis lacks empirical support. (2) Two of the derived wing features that apparently evolved to suppress flight sound are the vane fringes and dorsal velvet of owl wing feathers. We raise and explore possible answers to three questions about the evolution and ecology of silent flight of owls: (1) do owls fly silently for stealth, or is it to reduce self-masking? Current evidence slightly favors the self-masking hypothesis, but this question remains unsettled.
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