Friday, November 24, 2017

Curve-billed Ruby-throated Hummingbird

A homeowner on our residential island called my attention to the bird pictured below in several photographs.  The heavily curved bill suggests this bird is tropical, but after putting out inquiries on Xeno-Canto, which reached many knowledgeable people in the Americas, it was decided by all who rendered an opinion that is was a bill deformity on a Ruby-throated Hummingbird ( Archilochus colubris) a species which is fairly common on the coasts of Georgia and South Carolina in winter.

This bird has been at the homeowners residence since the height of fall migration in September, to the best of their recollection.  I was made aware of it incidentally on 23 November 2017. They had no idea it was such a novelty, and they host Ruby-throats each winter. I looked at the shape of the head, the crown, the presence of a post-ocular spot, and the shade of gray on the cheek. The white terminal portion of the tail feathers seems longer than ordinary as well. I did see the beginning of a buffy breast and belly which caused added confusion. The thickness of the bill is notable, but it does not appear heavy when observing the bird in person. 

My sources are Stiles and Skutch, Birds of Costa Rica; Howell and Webb, Birds of Northern and Central America; Williamson, Hummingbirds of North America; and Sibley, The Sibley Guide to Birds.  There were no other matches, and since there is nothing on the Web about bill anomalies in Archilochus hummingbirds, I will leave this posted. 

Tuesday, April 18, 2017

Tracking Hummingbird Development

I had the unique opportunity this past winter to follow the development of an immature Ruby-throat. I first shot the bird on December 17, but I had noticed it about one week earlier, because it perched on a single bare, and obscure twig at the top of a shrub, near a feeder.  It used this perch all through through April 14 when it finally left. Along the way I got to witness swooping courtship flight and watched it fly-catching insects, two aspects of hummingbird behavior I had not seen before.

I need to digress here, and mention that on the coast of Georgia, at least in Chatham County, we regularly have a good number of wintering hummingbirds.  I had over 70 homeowners report at minimum of 125 birds. More than 90 birds were reported from the suburban island where my home is located. It is all a matter of who had feeders out. Most were Ruby-throats of course, but Black-chins and Rufus were in the mix, and I photographed some of them. Through careful observation and examining images, a few of us realized these birds, even foraging next door to one another, are not usually the same bird.  So, there is little double-counting. Many of the homeowners told me they have had birds every year, for many several years, yet the species is still listed as rare on the coast of Georgia in winter.

Part of my interest was to observe how, and when, the bird molted into adult plumage, and developed the characteristic ruby-red gorget. Not unlike other birds which winter here, most notably American Goldfinch, the molt takes place at the end of winter.  Male goldfinches, and presumably others of that family, take about three weeks to transform themselves, and then hang out for another 2 or 3 weeks before migrating back to their breeding territory. This hummingbird changed very slowly and imperceptibly over several weeks, and then in a rush it was done.  Along the way iridescent feathers would appear, and then disappear. The gorget was nearly filled in by March 25, and surprisingly a large white patch on the chin redeveloped (March 28).  In the last of these shots on April 13, there are only a few white feathers on the chin. The next day April 14, the molt was complete.  That was the last day the bird seen.

December 17, 2016

December 28, 2016

January 24, 2017

January 29, 2017

March 22, 2017

March 28, 2017

April 13, 2017