The Great-Tailed Grackles of the Southwest

Abstract

Since 1913, a general northward invasion of Great-tailed Grackles has taken place in southern Arizona, New Mexico, and adjacent parts of southwestern Texas and northern Mexico. Two distinct races are involved, and the future will probably produce mingling of these races. Ornithologists should make careful observations and collections, especially of females, as this unusual situation develops. One of the races involved is Cassidix mea Huey, 1942) ; the other has been in doubt. As early as 1934, van Rossem‘( 1934:476) called attention to the small bills of four males from the city of Chihuahua; he had seen no females. Lowery (1938) was likewise handicapped by paucity of specimens from the plateau when he described the bird of the Texas lowlands. Since then, thanks largely to the discriminating collecting of Gale Monson and of A. E. Borell, a number of females have been taken in the upper Rio Grande valley and vicinity. These show that the birds of the northern plateau of Mexico resemble most closely the nominate race and are more distinct from the paler races of the adjacent coastal lowlands. They may be known as