Eye-ring coloration is not a reliable indicator for aging Mangrove Cuckoos (Coccyzus minor)

• Published in: The Wilson journal of ornithology Vol. 129; no. 1; pp. 163 - 165
• Main Authors: Frieze, Rachel D., Lloyd, John D.
• Format: Journal Article
• Language: English
• Published: Fort Collins The Wilson Ornithological Society 01.03.2017; Wilson Ornithological Society
• Subjects: age determination; Age determination (Biology); Age determination (Zoology); bare-part coloration; Bird coloration; Bird colouration; Birds; Coccyzus minor; Color of birds; Cuckoos; Eye; Mangrove Cuckoo; Methods; Observations; Physiological aspects; Seasons; SHORT COMMUNICATIONS; Small mammals; soft-part coloration; Florida; North America
• ISSN: 1559-4491; 1938-5447
• DOI: 10.1676/1559-4491-129.1.163

Soft-part coloration can be a useful method for determining the age of a bird. For example, hatch-year and early second-year Mangrove Cuckoos (Coccyzus minor) are supposedly distinguishable from older birds based on the presence of a dusky gray eye-ring; individuals gain a vivid yellow eye-ring in their second year of life that they retain for the rest of adulthood. However, observational data collected on banded Mangrove Cuckoos throughout the year indicate that eye-ring coloration varies seasonally rather than with age. We captured and banded two individuals in early spring, each with a yellow eye-ring. Re-sightings of these individuals later in the spring and early summer revealed that the eye-ring had changed to a dusky gray color. Subsequent re-sightings of these individuals again in the fall and winter revealed that both once again had a yellow eye ring. In reviewing photographs and notes taken during observation of marked and unmarked individuals, we determined that this pattern—a yellow eye-ring during late summer, fall, and winter (nonbreeding) and a dusky-gray eye-ring during spring and early summer (breeding)—was consistent across individuals in the population in Florida that we studied.