Rufous/Allen’s – addendum

I emailed Sheri Willimason (well known and respected birder with a penchant for hummingbirds) about selasphorus hummingbird identification, as it pertains to Rufous/Allen’s types and the ageing and sexing. With regards to my post on the CT bird, she corrected some information and kindly wrote the following illuminating reply:

Hi, Julian,
Though primary molt is often helpful in hummingbird identification, in this case it’s a red herring. The “generic” shape and narrow white tip of R2 (cp. Peterson Field Guide to Hummingbirds, pl. 24-25) are characteristic of a juvenile female, though in this case one in precocious primary molt (early even for an adult).

Gorget pattern is highly variable in female and juvenile male Rufous and Allen’s. Juvenile females may have nearly immaculate gorgets with no orange iridescence and bronze-green spangling concentrated at the margins, heavy bronze-green “five-o’clock shadow” typical of juvenile males, lightly marked gorgets with small central patches of adult-like iridescence, and anything in between. The presence of extensively iridescent gorget feathers next to predominantly white ones with small, drab spangles is strongly suggestive of a juvenile female acquiring her first adult gorget, which would not be surprising considering the condition of her primaries.

The amount of rufous in the uppertail coverts is highly variable within and between age/sex classes of Rufous/Allen’s, but I’m unaware of any evidence suggesting consistent species-specific differences that would be useful in identification.

Both probability and tail characteristics argue in favor of Rufous, but juvenile females are the most difficult age/sex class to identify. Even their measurements overlap extensively; a few individuals remain ambiguous with the bird in one hand, calipers in the other, and Table 1 in Stiles 1972 available for reference. To rephrase what I wrote to Nick: The options supported by the existing evidence are “probable Rufous” and the more conservative “Rufous/Allen’s.” The only practical ways to absolutely confirm the ID beyond a shadow of a doubt are in-hand measurements by a bander or new photos after she replaces her tail.

Hope this helps.

Sheri L. Williamson

Thanks to Sheri, it seems that the matter of identifying these two species is even more dire than I thought!


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