The least grebe is the smallest New World grebe, measuring just 9.5 inches in length and weighing approximately 112–161 g. It ranges from the southwestern United States and Mexico through Central and South America. In Arizona, however, it is treated as an accidental or casual visitor, appearing irregularly in the state’s southern counties.
Arizona’s first confirmed records date back to 1976, when a lone individual was observed at Guevavi Ranch in Santa Cruz County. Since then, additional sightings have been documented at a handful of wetland sites—including El Rio Preserve, the Avra Valley wastewater-treatment plant, Gilbert Water Ranch, Glendale Recharge Ponds and areas along the lower Colorado River.
Most Arizona records occur from late spring through early winter, reflecting post-breeding dispersal from Mexican populations. Birds are almost invariably seen singly on small freshwater or brackish wetlands—such as sewage lagoons, irrigation reservoirs, and marshy ponds—where emergent vegetation offers cover. Despite these seasonal visits, no breeding has ever been confirmed within Arizona.
