ABSTRACT
The plain chachalaca (Ortalis vetula mccalli) is the northernmost member of the family Cracidae, a group of gallinaceous birds found throughout much of South and Middle America. The natural range of this subspecies includes eastern Mexico from central Vera Cruz northward to southern Texas, where it inhabits dense riparian vegetation in the Lower Rio Grande Valley. Plain chachalacas are shy, elusive birds with drab plumage, making them difficult to observe under even the best field conditions. These birds are most active in the early morning and evening; they roost together in small family groups at night. This species is easily counted during the morning hours of the spring and early summer; the birds respond readily to recorded calls at distances of up to 180 m. Circular areas of suitable habitat within 180 m from the tape recorder comprise 10.5 ha (or estimated portions thereof) and can be used in estimating density.
