First record of Grasshopper Sparrow Ammodramus savannarum breeding in the grasslands of northern Mexico, with notes on nesting sites and habitat

Grassland birds are one of the most rapidly declining bird guilds in North America, likely as a result of the loss and degradation of native grasslands. The Grasshopper Sparrow (Ammodramus savannarum), a migratory grassland bird of North America, relies on dense, relatively tall grasses with low shrub densities. In Mexico, 4 subspecies of A. savannarum have been reported; however, the distribution of the species in the summer is poorly known, with only 2 records from northern Mexico within the states of Zacatecas and Chihuahua. Here, we report on the presence and nesting activity of A. savannarum in the Cuchillas de la Zarca Grassland Priority Conservation Area in northern Durango, Mexico. We describe the morphometric characteristics of the birds captured, speculate on subspecies designation, and report on characteristics within the territories of singing males and habitat at the nest site. The Cuchillas de la Zarca region is one of the most important sites for wintering grassland birds, particularly A. savannarum, but faces threats such as shrub encroachment caused by poor grazing management. Here we present evidence that this region also provides breeding habitat for the Grasshopper Sparrow, further highlighting its value as a priority area for the conservation of grassland birds.