An Experimental Field Study of the Function of Crested Auklet Feather Odor

During the breeding season, female and male Crested Auklets (Aethia cristatella; Alcidae) emit a pungent citruslike odor from their plumage. Previous experiments showed that captive birds oriented toward sources of the natural odor and toward isolates of its major constituents, cis-4 decenal and octanal, and avoided a noxious odor. In a blind experiment we manipulated odor on 12 life-sized, realistic Crested Auklet models (6 males, 6 females) to test for a social or sexual preference for the odor isolates in a natural setting. Based on the quantified behavior of 555 males and 280 females that approached the models at a breeding colony, we found no evidence for a sexual preference for models with added odor. Female auklets that approached male models with artificially added odor were no more likely to perform sexual displays than females that approached control models with less odor. Fewer males approached female models but the effect was the same: males that approached female models with artificially added odor were no more likely to perform sexual displays. However, males approached scented male models more closely and for longer duration than they approached control male models, and females approached scented male models more closely. Our findings confirm previous experiments with captive birds and further suggest that Crested Auklets' plumage odor serves at least a general social function. Estudio Experimental de Campo de la Función del Olor de las Plumas en Aethia cristatella Resumen. Durante la estación reproductiva, el plumaje del macho y la hembra de Aethia cristatella (Alcidae) emite un olor picante-cítrico. Experimentos previos han demostrado que las aves en cautiverio se orientan hacia fuentes de olor natural y hacia extractos de sus principales constituyentes, cis-4 decano y octano, y evitan un olor nocivo. En un experimento a ciegas, manipulamos el olor en 12 modelos de tamaño real de A. cristatella (6 machos y 6 hembras) para probar la preferencia sexual o social por los extractos en un ambiente natural. Basados en el comportamiento cuantitativo de 555 machos y 280 hembras que se acercaron a los modelos en la colonia reproductiva, no encontramos ninguna evidencia por una preferencia sexual por los modelos con el olor añadido. Las hembras de A. cristatella que se aproximaron a los modelos con el olor artificial añadido no presentaron una probabilidad mayor de realizar despliegues sexuales que las hembras que se acercaron a modelos con poco olor (control). Sin embargo, los machos se acercaron más y por más tiempo a los modelos de macho con olor que a los modelos de macho control, y las hembras se acercaron más a los modelos de macho con olor. Nuestros resultados confirman experimentos previos en aves en cautiverio y sugieren que el olor del plumaje de A. cristatella tiene por lo menos una función social general.