[All photographs copyright, Gary Nunn 2015] – I discovered this “Thick-billed” Fox Sparrow Passerella (iliaca) megarhyncha on 19 April 2015 furtively scratching among leaf litter inside a thicket at the south end of Point Loma Nazarene University, Point Loma, San Diego County, California. The lighting was awful for photography but I wanted to document this localized form of Fox Sparrow here in San Diego. It gave a subdued song phrase several times while I watched it moving about under the thicket. The massive bill structure is obvious on this bird, the bill being mostly bluish-gray in coloration with a barely discernible patch of pale yellow remaining on the lower mandible. Other useful field marks include the mostly whitish underparts only lightly patterned with small well defined dark blackish chevrons, grayish head and back, and wing and tail feathers generously edged with bright rufous coloration contrasting with the grayish body color. The very large bill appears strengthened by a pronounced ridge along the culmen, visible when it looks directly at the camera, and it shows a very swollen lower mandible structure. I did get too close, startling the bird, and it gave the loud “chink” call characteristic of this form of Fox Sparrow and which sounds remarkably similar to California Towhee.
My impression is that Thick-billed Fox Sparrows appear here in San Diego in a southbound wave in the fall, with a small number remaining in the winter, followed by a smaller northbound wave, probably less easily detected, in the spring. As far as is known they are short range migrants moving south and back north to their higher elevation breeding grounds in the Sierras and local southern California mountain ranges. Birds of this form are already singing on higher elevation mountaintops in Riverside County being reported on 18 April 2015 as close as Santa Rosa Mountain.