Pigmented gametocytes of Plasmodium spp. Plasmodium spp. are protozoan parasites which occur in many species of birds and are the cause of avian malaria. Transmitted by mosquitoes, infection with Plasmodium can be a cause of hemolytic anemia in some species (canaries, penguins, poultry, ducks, pigeons and falcons).       In addition to pigment-bearing gametocytes (pictured), both trophozoites and schizonts may be observed in peripheral blood erythrocytes. Notice the distortion of the erythrocyte and the displacement of its nucleus by the large gametocytes.