American White Ibis - Parasites and Mortality

Parasites and Mortality

Causes of death of adult ibis are not well known. Alligators could feasibly prey on nesting ibises but there has been little research in the area. A flock of fifty adult American White Ibis were killed in a fire in the Everglades. The corpses were found in a dense swathe of cattail (Typha angustifolia), which suggested they had taken shelter there. It is unclear why they had not been able to fly away from the fire, but one hypothesis was that they had been foraging for insects disturbed by the fire.

A total of 51 species of parasitic worm have been recovered from the American White Ibis, predominantly from the gastrointestinal system and particularly the small intestine. These include Cestoda (tapeworms), Acanthocephala (thorny headed worms), Nematoda (roundworms), Digenea and Spirurida. Several roundworm and spirurid species have been found in the lining of the gizzard. Nematodes are more prevalent in American White Ibis from freshwater habitats, and cestodes more frequent in those from saltwater areas. One nematode found in adult birds, Skrjabinoclavia thapari, is borne in the fiddler crab as an intermediate host, while the thorny headed worm species Southwellina dimorpha is carried in crayfish and infests both adult and juvenile ibis.

Parasitic protozoa of the genus Sarcocystis have been recovered from the smooth muscles of adult American White Ibis, and another species, Haemoproteus plataleae, has been recovered from the blood of adults and nestlings, and can hence be transmitted before the young leave the nest. The larvae of two species of mite of the family Hypoderidae, Phalacrodectes whartoni and Neoattialges eudocimae, have been recovered from under the skin. Two species of the louse suborder Mallophaga, Plegadiphilus eudocimus and Ardeicola robusta, also parasitise the bird.