Оахакская овсянка Aimophila notosticta

Very local and endemic to interior of Oaxaca, where replaces larger and bulkier Rusty Sparrow (no known range overlap). Favors brushy woodland and edge and oak thickets with adjacent grassy areas. Usually rather skulking, on or near the ground, but often feeds at edges early and late in the day. Sings from more conspicuous perches in bushes and trees. Note the all-black bill and strong face pattern, with black lores setting off the broken white eyering.