title: Foraging for carotenoids: do colorful male hihi target carotenoid-rich foods in the wild?
abstract: Dietary access to carotenoids is expected to determine the strength of carotenoid-based signal expression and potentially to maintain signal honesty. Species that display carotenoid-based yellow, orange, or red plumage are therefore expected to forage selectively for carotenoid-rich foods when they are depositing these pigments during molt, but whether they actually do so is unknown. We set out to address this in the hihi (Notiomystis cincta), a New Zealand passerine where males, but not females, display yellow carotenoid-based plumage. We measured circulating carotenoid concentrations in male and female hihi during breeding and molt, determined the nutritional content of common foods in the hihi diet, and conducted feeding observations of male and female hihi during molt. We found that although male and female hihi do not differ significantly in plasma carotenoid concentration, male hihi have a greater proportion of carotenoid-rich foods in their diet than do females. This is a consequence of a greater fruit and lower invertebrate intake than females and an avoidance of low-carotenoid content fruit. By combining behavioral observations with quantification of circulating carotenoids, we present evidence that colorful birds forage to maximize carotenoid intake, a conclusion we would not have drawn had we examined plasma carotenoids alone.
authors.affiliation: Department of Zoology, University of Cambridge , Downing Street, Cambridge CB2 3EJ , UK , ; Institute of Zoology, Zoological Society of London , Regent's Park, London NW1 4RY , UK .
authors.forename: Leila K
authors.initials: LK
authors.lastname: Walker
authors.affiliation: Department of Zoology, University of Cambridge , Downing Street, Cambridge CB2 3EJ , UK .
authors.forename: Rose
authors.initials: R
authors.lastname: Thorogood
authors.affiliation: Department of Animal Science, Faculty of Agriculture, University of Yüzüncü Yil , Van 35080 , Turkey , and.
authors.forename: Filiz
authors.initials: F
authors.lastname: Karadas
authors.affiliation: Charles Perkins Centre and Faculty of Veterinary Science and School of Biological Sciences, University of Sydney , Sydney , NSW 2006, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Raubenheimer
authors.affiliation: Department of Zoology, University of Cambridge , Downing Street, Cambridge CB2 3EJ , UK .
authors.forename: Rebecca M
authors.initials: RM
authors.lastname: Kilner
authors.affiliation: Institute of Zoology, Zoological Society of London , Regent's Park, London NW1 4RY , UK .
authors.forename: John G
authors.initials: JG
authors.lastname: Ewen
keywords: carotenoids; foraging; hihi; nutrition; plumage.