17 August 2014 – Ruby-throated Hummingbird (I think)

Today marked the inauspicious observance of the first window-killed bird at the Noble Research Center for fall, 2014.  It was a hatch year Archilochus hummingbird at the southwest alcove that I have somewhat tentatively identified as a Ruby-throated. To nail down the identification as best as I could, I consulted David Sibley’s the Sibley Guide to Birds (2000) and Peter Pyle’s Identification Guide to North American Birds (1997).

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Step 1 for identification of these hummingbirds is to confirm the age.  As hatch-year hummers develop, their bills lose characteristic striations or corrugations over time. A hummingbird with these markings extending for > 10% the length of the bill can be reliably considered HY/SY (i.e., less than 1 year old).   Here’s this morning’s bird (with bonus photo of hummingbird tongue tip):

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The markings are evident over probably 90% of the bill length. This is a hatch-year bird.

The problem with the bird is that it presents some characters (admittedly subjective in some cases) that suggest Black-chinned more strongly than Ruby-throated.  For example, there is low contrast between the auriculars and the throat, and that throat is spotted.  Both of these are Black-chinned characters as rendered by Sibley. The flanks are dirty gray with just a hint of cinnamon – also suggesting Black-chinned.  More pronounced is the relative length of folded wing and tail:  If anything, the wingtips extend beyond the tail tip as opposed to obviously shorter than the tail as typical for Ruby-throated. 

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So it was going to take some measurements to help solve this puzzle.  The wing chord came in at 46.5mm:  that’s too big for a male of either species.  So with that information, I knew I now had a HY, female hummingbird.

The length of the tail (24.9), culmen (18.8), and tail fork (0.10) – and the width of the outermost tail feather (r5, 5.2) offered no help in determining which HY female Archilochus I had.  However, the shape of the outer primary (p10) and primary #6 (p6) were both in line with expectations for Ruby-throated.  The photos aren’t great, but p6 is featured in the next two photos:

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So, based on my analysis of the characters this bird presented, I’m calling her a Ruby-throated Hummingbird.  The possibility of hybrids is very real for this species and Black-chinned, however, so I will be sharing this information with some more experienced folks to get some other opinions.  Stay tuned!