Carotenoids and throat pouch coloration in the great frigatebird (Fregata minor).
Carotenoid pigments are a common source of red, orange, and yellow coloration in vertebrates. Animals cannot manufacture carotenoids and therefore must obtain them in their diet to produce carotenoid-based coloration. Male great frigatebirds (Fregata minor) display a bright red inflated gular pouch as part of their elaborate courtship display. The basis of this coloration until now has not been investigated. Using high-performance liquid chromatography (HPLC), we investigated the types and concentrations of carotenoids that great frigatebirds circulate in their plasma and whether male gular pouch coloration was carotenoid-based. Great frigatebird plasma collected during the breeding season contained three carotenoid pigments in dilute concentrations-tunaxanthin, zeaxanthin, and astaxanthin-with astaxanthin accounting for nearly 85% of the carotenoids present. Astaxanthin was the only carotenoid present in gular pouch tissue, but the concentration is the highest reported for any carotenoid-pigmented avian tissue. Throat pouch reflectance curves were measured with a UV-VIS spectrophotometer, revealing a complex pattern of one UV peak (approx. 360 nm), two absorption valleys (approx. 542 and 577 nm), followed by a plateau at approx 630 nm. The reflectance curve suggests a role for additional pigments, in particular hemoglobin, in the production of color in this ornament.
Department of Biology, University of Miami, Coral Gables, FL 33146, USA. frans@bio.miami.edu
Frans A
FA
Juola
Kevin
K
McGraw
Donald C
DC
Dearborn
D000818:Animals; D001717:Birds / Q000097:blood / Q000378:metabolism / Q000502:physiology*; D002338:Carotenoids / Q000097:blood / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology*; D005260:Female; D008297:Male; D010614:Pharynx / Q000378:metabolism / Q000502:physiology*; D010858:Pigmentation / Q000502:physiology*; D012098:Reproduction / Q000502:physiology; D012726:Sexual Behavior, Animal / Q000502:physiology; D024341:Xanthophylls / Q000032:analysis / Q000097:blood; D065146:Zeaxanthins
D024341:Xanthophylls; D065146:Zeaxanthins; D002338:Carotenoids; C005948:astaxanthine