ML514584251

Age

Not specified

Sex

Not specified

Observation details

I got several excellent views of the bird as it moved across the liria on the river’s ege. I considered Lincoln’s Sparrow, of which we had seen several that morning, but the proportions of the bird, especially the bill, were heavier and there was no buff wash on the breast. The central "tie-pin” spot was also clearly seen surrounded by rather thick brown stripes and smudges on a whitish background. The throat was white. I referred to my copy of “The Song Sparrows of the Mexican Plateau” by Robert W. Dickerman, 1963, Univ of Minnesota Press) and found Fig. 19 of the “Rio Lerma Basin” showing the distribution of SOSPs in the Lake Chapala area. There is shading where the Lerma River meets Lake Chapala (indicated with red arrow in attached figure), and he calls this “enigmatic" subspecies" M.m. adjusta. He describes this cluster of subspecies as: “Known only from the marshes of the east end of Lago Chapala, in the vicinity of Ocotlan, and along the lower Lerma River near at La Barca (Fig 19).” Birds of the World lists three subspecies on the Mexican Plateau (adusta, villai, mexicana) and lumps zacapu into M.m. adusta. Here is that description: "M. m. adusta Nelson, 1899. Includes as synonyms M. m. yuriria Phillips and Dickerman, Phillips and Dickerman 1957; and M. m. zacapu Dickerman, Dickerman 1963a (Marshall 1964b). Type locality Lago Pátzcuaro, Michoacán, Mexico. Resident along Río Lerma drainage in Michoacán from Zacapu to Lago Yuriria, Guanajuato. Black-spotted below, with wide black dorsal streaks on reddish-brown background and clean white throat. Clinal variation within subspecies, with reddest, darkest birds in west and brownest birds in east.” https://birdsoftheworld.org/bow/species/sonspa/cur/systematics#subsp The bird I saw fit into that “reddest, darkest” subset. So, the available evidence, coupled with my decades of experience with the species in (mostly in California and Oregon) suggests strongly that the bird I reported was a resident M.M. adusta. It’s encouraging to find that this disjunct subpopulation still exists, given the habitat modification that has occurred in that area over the last few decades.

Technical information

Model

iPhone 13 Pro

Lens

iPhone 13 Pro back triple camera 1.57mm f/1.8

ISO

250

Focal length

1.6 mm

Flash

Flash did not fire

f-stop

f/1.8

Shutter speed

1/60 sec

Dimensions

480 pixels x 640 pixels

Original file size

107.41 KB