Ammodramus savannarum ammolegus (commonly referred to as the Arizona Grasshopper Sparrow) occurs in the desert and plains grasslands of southeastern Arizona, southwestern New Mexico, and northern Sonora, Mexico. Although a subspecies of conservation concern, this data was produced as part of the first intensive study of its life history and breeding ecology, providing baseline data and facilitating comparisons with other North American Grasshopper Sparrow subspecies. This study is described in the publication listed in the larger work citation of this metadata record. In 2011 through 2013, I mapped territories of male Grasshopper Sparrows and calculated territory size. A 95% kernel density estimate was used to calculate territory size.