Thursday, June 6, 2013

Enlarged photo of Yellow-billed Cuckoo


I further cropped one of the photos below to super enlarge the face of this Yellow-billed Cuckoo to show it's grayish orbital ring. I haven't often either viewed a Yellow-billed Cuckoo up close or taken photos that provide the close-up views as I did with the bird I found yesterday in Van's Grove. I have seen in Sibley's and National Geographic (6th ed) that they have a yellow orbital ring and show drawings of both adult and juvenile birds with yellow orbital rings. When I cropped my photos to enlarge them it was clear that the bird I found did not have a yellow orbital ring-it was grayish. So I did some reading and now am confused. Birds of North America online states, "Orbital skin pale yellow in nestling; grayish in adult." McGill Bird Observatory (has banding photos) states, "A quick and reliable way to determine age in Yellow-billed Cuckoos is by the orbital ring, which is yellow in HY/SY birds (until late winter or spring) and grayish in older individuals." So, I wonder if anyone here has expertise with these cuckoos to address this apparent contradiction? I say apparent as a possibility is that both Sibley as well as Jon Dunn and Jonathan Alderfer ignored the yellow coloration on the orbital rings of the drawings of juvenile birds in their respective field guides (??). SeEtta