What's Different About These Common Birds? Part 2

The San Lucas Robin

The resident subspecies of American Robin (T. m. confinis) in Baja California Sur (B.C.S.) — often referred to as the San Lucas Robin — is every bit as confounding as the House Finch shown in the previous post. This taxon formerly enjoyed full species status, but was later lumped with the American Robin. San Lucas Robins are much paler above and below than American Robins found north of the U.S./Mexico border. Their bills are mostly rich orange rather than yellow in color, and these birds show a well-defined white supercilium in all plumages. It should be noted that some robins in the U.S. show a weak supercilium, but it is typically far less eye-catching. The flight calls of San Lucas Robins are noticeably higher-pitched and squeakier than those of their more northerly counterparts. I have not heard San Lucas Robins sing, but Steve Mlodinow, my birding mate during this Baja trip, and a veteran of several previous B.C.S. explorations, assures me that the song is distinctly different as well. The robins here are yet another example of a geographically isolated population that has evolved to look quite different than others within their species.

The American Robin above, likely a female based on the paler edgings to the breast and belly feathers and the brown tones on the upper back and wing coverts, was photographed 18 December 2008 in Kirkland, Washington. The orange below is paler than what is exhibited by a typical adult male (see below), and the head is mostly gray with a bit of brown rather than being mostly black. The bill is not as bright yellow and shows a dark culmen (ridge along the top of the upper mandible). (Photograph taken by Ryan Merrill using a Nikon D300 & AF-S 70-300mm f/4.5-5.6 VR lens)

The adult male American Robin shown above was photographed in Springfield, Oregon on 3 February 2007. Note the entirely yellow bill with no dark on the culmen, the fairly dark slate-gray back, and the mostly black head. This bird shows broad white eye arcs, but does not show a white supercilium. The underparts are predominantly uniform burnt orange and lack the pale feather margins usually seen on females and young males. (Photograph by Sylvia Maulding using a Sony DSC-H1 camera)

The female San Lucas Robins in the two images above differ from female American Robins in several ways. Among the most prominent field marks is the distinctive white supercilium, which extends well past the eye. Some female and immature American Robins can show whitish superciliums, but they are not as well-defined, or as clean white as they are on these birds. The overall coloration of San Lucas Robins is much paler, particularly on the underparts. Female San Lucas Robins are generally more buff than orange one the breast and upper belly. Their lower belly, undertail and lower flanks show more extensive white than the female American Robins in the U.S. Their upperparts tend to lack the charcoal gray tones shown by American Robins, instead they often appear more brown than gray above. Also note the weak whitish wingbar, which is often shown by female San Lucas Robins. The bills of San Lucas Robins are mostly orange rather than yellow, and both males and females have a dark culmen. Female American Robins also show a dark culmen, but the rest of the bill is typically more yellow. Finally, the bills of San Lucas Robins often give the appearance of being a bit longer and heavier than those of American Robins. (Photos by David Irons using a Canon EOS XSI 450D camera and a EF 100-400mm f/4.5-5.6 lens)

The adult male San Lucas Robin in the images above is quite unlike an adult male American Robin. Its overall coloration is much paler above and below. Like the females, it also has a strongly orange bill with a dark culmen and dark tip. Adult male American Robins typically show an entirely yellow bill. The crown (see bottom image) and nape have a brownish cast and there is no black on the head, nape or back. The upperparts of male San Lucas Robins have a more brownish cast than the typical dark charcoal gray to black (mostly on the head) upperparts of male American Robins in the U.S.. The orange below is much paler and might better be described as “peach” or “salmon” rather than the deep burnt orange exhibited by an adult male American Robin. Lastly, adult male American Robins do not show a white supercilium. (Photos by David Irons using a Canon EOS XSI 450D camera and an EF 100-400mm f/4.5-5.6 lens)

In the final installment of this three-part series, we’ll examine the Acorn Woodpeckers of Baja California Sur. This species, the only woodpecker native to both North and South America, shows a number of plumage variations across its expansive north-south range. However, the B.C.S. population exhibits two characteristics not shown by other populations of Acorn Woodpeckers.

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Hello,
I am a photo researcher working on a college textbook Concepts in Biology…………I am in need of a photograph of a San Lucas Robin for our book. I would need a high resolution digital file. I was wondering if you would be willing to submit a photo for our use?
Thank you
LouAnn

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wow

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Helene – THANK YOU two so much for sharing these beatuiful photographs! We just had a very emotional moment of revisiting these amazing memories from our symbolic destination wedding. Thank you for giving me gooeys for the rest of the day! ..I think for the rest of our lives, we can treasure these. Love your vintage treatment on the wedding day batch. You two have such a gift in capturing the true emotion of each and every experience we had.That black SUV with the OTT (over the top) tint, definitely gave us the heebie jeebies .I was worried we would end up getting robbed or worse ..kidnapped and sold to a sweatshop making llama hair ponchos! Then none of us would be married right now!!

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