July 2003 Mystery Bird

This month's mystery bird was photographed 15 June 2003 near Lovell, Wyoming.

It is either an Eastern Kingbird with an unusual amount of yellow on the underparts, or it is a hybrid between Eastern Kingbird x Western Kingbird. The size, shape, etc. all match Eastern Kingbird. Dr. Ginest sent me a few other images of this bird, including one showing the back. I include it here below right. This shows that the wing coverts and some tertials as well as scapulars are brown contrasting with gray back. The outermost tail-feather looks tapered, so I think this bird is in its first calendar year. The tail tip also looks quite worn. We should be able to age this bird based on this, but I am confused by the account in Pyle. The chart on page 264 of Identification Guide to North American Birds shows Juv-HY from June through December, while the text says August on.

Discussion on ID-Frontiers brought to light another somewhat similar bird seen this spring at Anahuac NWR in Texas. A photo by Jo Heindel is here. Opinion was divided between whether that bird was a hybrid, or possibly an Eastern Kingbird with yellow underparts. The voice was said to be indistinguishable from Eastern Kingbird. I don't think a consensus was reached on that bird.

Hybrid kingbirds are apparently quite rare. We learned of a mixed pair of Eastern x Western Kingbirds which nested in Maryland. However the young were indistinguishable from Eastern Kingbirds. Tony Leukering reported a mixed pair of Eastern x Western Kingbirds in Michigan. The young resembled Western Kingbirds, but had a white band on the tail tip. It was also brought out that the young in a kingbird nest, may not necessarily have been the offspring of the attending birds. There is a great deal of extra-pair copulation in these species. See: Rowe, D. L., M. T. Murphy, R. C. Fleishcer, and P. G. Wolf. 2001. High frequency of extra-pair paternity in Eastern Kingbirds. Condor 103:845-851.

Our mystery bird certainly has Eastern Kingbird parentage, but whether it is a "pure" Eastern Kingbird remains a mystery. However, I think it does show a white edge to the outer web of r6 suggesting hybrid parentage. Thanks again to all contributors.

Photo © 2003 Dr. Mel Ginest. All rights reserved.

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