Possible relationships between morphology, territory quality, and skin color of American Kestrels

Abstract

Carotenoid-based coloration of skin and plumage has been found to be correlated with individual quality in many species of birds during the breeding season. However, less is known about the possible role of these signals during the nonbreeding season, particularly among nonpasserines that defend winter territories. American Kestrels (Falco sparverius) are sexually dimorphic raptors that defend winter territories and possess carotenoid-based morphological features known to be correlated with individual quality. Much is known about winter territory use and habitat segregation by male and female kestrels, but possible relationships among morphological features, individual quality, and habitat quality have not been examined. Our objective was to examine possible relationships between morphology, territory quality, and skin color of American Kestrels. Male kestrels had brighter skin than females, and the skin color of male kestrels was positively correlated with size (wing chord and tail length) and territorial quality (hunting territories with less canopy and more grass cover). No such relationships were found for female kestrels. Skin color appears to be an honest indicator of quality for male American Kestrels and may serve both intersexual (territory acquisition) and intersexual (mate choice) functions during the breeding and nonbreeding seasons. SINOPSIS. Posible relación entre la morfología, calidad del territorio y el color del integumento en Falco sparveriusSe ha encontrado que la coloración de plumas e integumento, asociada a la ingestión de carotenoides, está correlacionada con la calidad de individuos en muchas especies, durante laépoca reproductiva. Sin embargo, se conoce poco sobre el posible rol de estas señales durante laépoca no-reproductiva, particularmente entre paserinos que defienden territorios durante el invierno. Falco sparverius es un tipo de falcón sexualmente dimorfico que difiende territorio durante el invierno y tiene estructuras morfológicas cuyo pigmento está basado en carotenoides los cuales, a su vez, están correlacionados con la calidad de los individuos. Se conoce bastante sobre el uso de territorios durante el invierno y segregación de hábitat por parte de ambos sexos, pero nos se ha estudiado la posible relación entre aspectos morfológicos, la calidad de los individuos y la calidad del hábitat utilizado. Nuestro objetivo fue examinar la posible relación entre morfología, calidad del territorio y color del integumento en los falcones. El macho de la especie tiene un integumento más brillante que la hembra y el color de este se correlacionó positivamente con el tamano (largo del ala y el rabo) y la calidad del territorio (territorio de caceria con poco docel y másáreas abiertas con yerbas). No se encontró un correlación similar en las hembras. El color del integumento parece ser un buen indicador de la calidad de los machos y pudiera servir para la adquisición de territorios y la selección de parejas tanto durante laépoca de reproducción como fuera de la misma.

Effects of Small Increases in Corticosterone Levels on Morphology, Immune Function, and Feather Development

“…In kestrels, short-term food restriction during the nestling period results in decreased contour feather brightness (Marzot 2007). Additionally, length of wing feathers in kestrels is correlated with bare-part coloration (Bostrom and Ritchison 2006), which may be a condition-dependent trait (Bortolotti et al 1996;Negro et al 1998). However, contrary to findings in other studies ), we did not see an effect of hormonal treatment on feather coloration, which suggests that the blue gray coloration of kestrels is not condition dependent, although further work is needed to verify this suggestion.…”

Assessing the usefulness of ptilochronology in the study of melanin‐ and carotenoid‐based ornaments in the Great TitParus major

“…The usefulness of ptilochronology has been challenged (Murphy & King 1991 , Takaki et al. 2001 , Kern & Cowie 2002 , van Oort & Otter 2005 , Bostrom & Ritchison 2006). Here, we did not test methods of conducting ptilochronology but used standard methods to compare the relationship between feather ornaments and feather growth from a large sample of birds.…”

“…However, the efficacy of the method might differ, for example, between sexes (Grubb 1989 , Takaki et al. 2001 , Bostrom & Ritchison 2006) or age categories (Grubb et al. 1991).…”

Developmental immune history affects adult immune function but not carotenoid‐based ornamentation in mallard ducks

“…2005; Ezenwa & Jolles 2008; Cogliati, Corkum & Doucet 2010), reflect an individual’s quality by being costly enough that only the highest‐quality individuals can produce and/or maintain the ornament (Allen & Levinton 2007). Fitness‐related information communicated by ornament expression includes territory quality (Bostrom & Ritchison 2006), parental ability (Senar, Figuerola & Pascual 2002), genetic quality (Hale et al. 2009) and immune function (Peters et al.…”

“…The honest advertisement model of sexual selection posits that ornaments, such as antlers, horns and bright colours (Lailvaux et al 2005;Ezenwa & Jolles 2008;Cogliati, Corkum & Doucet 2010), reflect an individual's quality by being costly enough that only the highest-quality individuals can produce and ⁄ or maintain the ornament (Allen & Levinton 2007). Fitness-related information communicated by ornament expression includes territory quality (Bostrom & Ritchison 2006), parental ability (Senar, Figuerola & Pascual 2002), genetic quality (Hale et al 2009) and immune function (Peters et al 2004a). Owing to the putative role of parasites in mediating the evolution of ornamentation (Hamilton & Zuk 1982), the ability of ornaments to reveal immune function has been studied extensively.…”