Grass Wren Cistothorus platensis

Tiny, bubbly, buffy-colored wren of dense grassy or shrubby habitats. Fairly common but locally distributed from central Mexico to the southernmost tip of South America; surely comprises multiple species. Occurs from open grasslands and marshes at sea level up to paramo in the high Andes. Generally secretive, but perches up when singing. Generally pale brownish with complex patterning on upperparts; compare with much plainer House Wren. Variable voice, usually including harsh chips, buzzes, and trills.