White Stork - Parasites and Diseases

Parasites and Diseases

White Stork nests are habitats for an array of small arthropods, particularly over the warmer months after the birds arrive to breed. Nesting over successive years, the storks bring more material to line their nests and layers of organic material accumulate within them. Not only do their bodies tend to regulate temperatures within the nest, but excrement, food remains and feather and skin fragments provide nourishment for a large and diverse population of free-living mesostigmatic mites. A survey of twelve nests found 13,352 individuals of 34 species, the most common being Macrocheles merdarius, M. robustulus, Uroobovella pyriformis and Trichouropoda orbicularis, which together represented almost 85% of all the specimens collected. These feed on the eggs and larvae of insects and on nematodes, which are abundant in the nest litter. These mites are dispersed by coprophilous beetles, often of the family Scarabaeidae, or on dung brought by the storks during nest construction. Parasitic mites do not occur, perhaps being controlled by the predatory species. The overall impact of the mite population is unclear, the mites may have a role in suppressing harmful organisms (and hence be beneficial), or they may themselves have an adverse effect on nestlings.

The birds themselves host species belonging to more than four genera of feather mites. These mites, including Freyanopterolichus pelargicus and Pelargolichus didactylus live on fungi growing on the feathers. The fungi found on the plumage may feed on the keratin of the outer feathers or on feather oil. Chewing lice such as Colpocephalum zebra tend to be found on the wings, and Neophilopterus incompletus elsewhere on the body.

The White Stork also carries several types of internal parasites, including Toxoplasma gondii and intestinal parasites of the genus Giardia. A study of 120 White Stork carcasses from Saxony-Anhalt and Brandenburg in Germany yielded eight species of trematode (fluke), four cestode (tapeworm) species, and at least three species of nematode. One species of fluke, Chaunocephalus ferox, caused lesions in the wall of the small intestine in a number of birds admitted to two rehabilitation centers in central Spain, and was associated with reduced weight. It is a recognised pathogen and cause of morbidity in the Asian Openbill (Anastomus oscitans).

West Nile virus (WNV) is mainly a bird infection that is transmitted between birds by mosquitos. Migrating birds appear to be important in spread of the virus, the ecology of which remains poorly known. On 26 August 1998, a flock of about 1,200 migrating White Storks that had been blown off course on their southward journey landed in Eilat, in southern Israel. The flock was stressed as it had resorted to flapping flight to return to its migratory route, and a number of birds died. A virulent strain of West Nile virus was isolated from the brains of eleven dead juveniles. Other White Storks subsequently tested in Israel have shown anti-WNV antibodies. In 2008 three juvenile White Storks from a Polish wildlife refuge yielded seropositive results indicating exposure to the virus, but the context or existence of the virus in that country is unclear.