Food color preferences against a dark, textured background vary in relation to sex and age in house finches (Carpodacus mexicanus)

Abstract

Many animals consume colorful foods, because bright coloration either enhances conspicuousness of food items or signals nutritional rewards. A comparatively under-studied aspect of food color preferences is the role of the background environment in shaping food detectability and choices. Previous work with house finches ( Carpodacus mexicanus), for example, showed that individuals preferred red and green food items and avoided yellow ones. However, this study of desert, ground-feeding birds was done with seeds presented against an artificial white background that is unlikely to reflect natural conditions. Therefore, we performed a similar experiment, but quantified selection of colorful foods using a different visual environment that better mimicked natural conditions. We mixed dark, inedible distractor pellets (i.e., analogous to natural desert sand and rocks) with sunflower kernels that were colored red, green, yellow, or orange to test for differences in foraging patterns by sex, age, and expression of male plumage coloration in non-molting house finches. This food presentation resulted in yellow seeds having a significantly greater chromatic, but not achromatic, contrast with the background than red or green seeds. Under these conditions, all birds consumed yellow, and to a lesser extent red, seeds most often, and both adult males and females had a strong preference for yellow kernels; adult males also tended to prefer green kernels, but females tended not to prefer green kernels. Juveniles showed no significant preferences for any seed color, and adult male plumage coloration was not related to seed color preference. Therefore, in contrast to studies using different foraging environments, house finches tended to prefer yellow seeds, supporting models that suggest that visual background and contrast may be more important than color per se in visually mediated foraging decisions of birds. Moreover, the fact that adult males and females differed in food color preference has not been reported previously in songbirds.

Do carotenoid‐based ornaments entail resource trade‐offs? An evaluation of theory and data

“…Unfortunately, questions related to environmental carotenoid limitation are difficult to answer under natural conditions wherein a population of birds may consume a wide variety of food items, individuals may differ in which and how much of those various items they consume, and the internal processes of carotenoid assimilation (which may differ among individuals, species, season and even specific carotenoid pigments; McGraw, 2005;Tella et al, 2004) are largely unknown in any given study system. Studies testing for preferences for carotenoidrich food in birds with carotenoid-based ornamentation have found only mixed support (Bascuñán, Tourville, Toomey, & McGraw, 2009;Behbahaninia, Butler, Toomey, & McGraw, 2012;Catoni, Metzger, Schaefer, & Bairlein, 2011;Senar et al, 2010), indicating that many colourful birds do not need to preferentially forage for carotenoidrich food in order to produce colourful ornaments (but see Walker et al, 2014). Currently, environmental carotenoid limitation is not widely considered to be a major determinant of carotenoid-based colour signalling (Hadfield & Owens, 2006;Møller et al, 2000;Svensson & Wong, 2011).…”

Developmental stress increases reproductive success in male zebra finches

“…We determined genetic paternity using six microsatellite markers previously developed for the zebra finch [52]. For each locus, we first used a single polymerase chain reaction (PCR) to genotype all parents from the breeding experiment (F 1 males and untreated mothers) to determine the range of allelic diversity for each locus.…”

Full Issue

“…higher chromatic contrast), the more conspicuous the object is from the background. Behavioral tests have corroborated the physiologically based predictions of perceptual models in foraging (Cazetta et al 2009, Behbahaninia et al 2012) as well as brood-parasitism (Avilés et al 2010) contexts.…”