Color expression in experimentally regrown feathers of an overwintering migratory bird: implications for signaling and seasonal interactions.
Plumage coloration in birds plays a critical role in communication and can be under selection throughout the annual cycle as a sexual and social signal. However, for migratory birds, little is known about the acquisition and maintenance of colorful plumage during the nonbreeding period. Winter habitat could influence the quality of colorful plumage, ultimately carrying over to influence sexual selection and social interactions during the breeding period. In addition to the annual growth of colorful feathers, feather loss from agonistic interactions or predator avoidance could require birds to replace colorful feathers in winter or experience plumage degradation. We hypothesized that conditions on the wintering grounds of migratory birds influence the quality of colorful plumage. We predicted that the quality of American redstart (Setophaga ruticilla) tail feathers regrown after experimental removal in Jamaica, West Indies, would be positively associated with habitat quality, body condition, and testosterone. Both yearling (SY) and adult (ASY) males regrew feathers with lower red chroma, suggesting reduced carotenoid content. While we did not observe a change in hue in ASY males, SY males shifted from yellow to orange plumage resembling experimentally regrown ASY feathers. We did not observe any effects of habitat, testosterone, or mass change. Our results demonstrate that redstarts are limited in their ability to adequately replace colorful plumage, regardless of habitat, in winter. Thus, feather loss on the nonbreeding grounds can affect social signals, potentially negatively carrying over to the breeding period.
Migratory Bird Center, Smithsonian Conservation Biology Institute National Zoological Park, Washington, District of Columbia ; School of Biology and Ecology, University of Maine Orono, Maine.
Christopher M
CM
Tonra
Department of Biological Sciences, Thompson Rivers University Kamloops, BC V2C 0C8, Canada.
Kristen L D
KL
Marini
Migratory Bird Center, Smithsonian Conservation Biology Institute National Zoological Park, Washington, District of Columbia.
Peter P
PP
Marra
Centre for Applied Conservation Research, University of British Columbia Vancouver, BC V6T 1Z4, Canada.
Ryan R
RR
Germain
School of Biology and Ecology, University of Maine Orono, Maine.
Rebecca L
RL
Holberton
Department of Biological Sciences, Thompson Rivers University Kamloops, BC V2C 0C8, Canada.
Matthew W
MW
Reudink
American redstart; Setophaga ruticilla; carotenoid; delayed plumage maturation; molt; plumage color