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