Hemosporid parasitism of mallards at the southern periphery of their breeding range.

Thin blood smears from 37 juvenile mallards (Anas platyrhynchos) collected in the Playa Lakes Region of Texas during summers 1990 and 1991 were examined for hemosporids. Only one bird was infected with a Plasmodium sp. Parasite intensity was seven per 10,000 erthrocytes. The low prevalence of Plasmodium sp. and the lack of other blood parasites in resident mallards suggests that hemosporid parasitism at the southern periphery of their breeding range is very different from that at the northern breeding grounds.