THE EXTERNAL PARASITES OF BIRDS: A REVIEW
2016; Wilson Ornithological Society; Volume: 63; Issue: 4 Linguagem: Inglês
ISSN
1938-5447
Autores Tópico(s)Study of Mite Species
ResumoBirds may harbor a great variety and number of ectoparasites. Among the insects are biting lice (Mallophaga), fleas (Siphonaptera), and such Diptera as hippoboscid flies (Hippoboscidae) and the very transitory mosquitoes (Culicidae) and black flies (Simuliidae), which are rarely if every caught on animals since they fly off as soon as they have completed their blood-meal. One may also find, in birds' nests, bugs of the hemipterous family Cimicidae, and parasitic dipterous larvae that attack nestlings. Arachnida infesting birds comprise the hard ticks (Ixodidae), soft ticks (Argasidae), and certain mites. Most ectoparasites are blood-suckers; only the Ischnocera lice and some species of mites subsist on skin components. The distribution of ectoparasites on the host varies with the parasite concerned. Some show no habitat preference while others tend to confine themselves to, or even are restricted to, definite areas on the body. A list of 198 external parasites for 255 species and/or subspecies of birds east of the Mississippi has been compiled by Peters (1936) from files of the Bureau of and Plant Quarantine between 1928 and 1935. Fleas and dipterous larvae were omitted from this list. According to Peters, it is possible to collect three species of lice, one or two hippoboscids, and several types of mites on a single bird. He records as many as 15 species of ectoparasites each from the Bob-white (Colinus virginianus), Song Sparrow (Melospiza melodia), and Robin (Turdus migratorius). The lice and plumicolous mites, however, are typically the most abundant forms present on avian hosts. A good introduction to this field of investigation is Medical Entomology by Matheson (1950). When collecting ectoparasites, the sooner the bird is examined the better, for the parasites. in particular the mites, are easier to see while they are still alive. If inconvenient to examine the freshly killed bird, it should be wrapped in cotton, placed in a refrigerator, and examined as soon as possible. By then most of the hematophagous ectoparasites will have left the skin, been entrapped by the cotton, and be readily visible thereon. The non-blood-suckers usually remain attached to the skin and feathers. Examination of the specimen should be conducted near a closed window in a strong light and under a binocular microscope. The feathers should be carefully turned back with forceps for inspection. Hippoboscids tend to fly toward the light and will thus be easily captured. The eyes, ears, head, back, legs, tail and wings (in particular the under surface of the remiges and under wing coverts) should be examined systematically. Special attention should be given the ventral body feathers and skin, especially around the vent. The roof of the mouth should be cut so as to expose the turbinals for possible nasicolous mites. The parasites may be removed with fine forceps (mites, with a fine needle previously dipped in alcohol) and preserved in 70% alcohol. Temporary or semipermanent microscopic preparations may be made in PVA-lactic acid medium (Pratt and Lane, 1949), or, if the ectoparasites are delicate and lightly chitinized, in chloral hydrate gum-arabic medium (Doetschman, 1944). Permanent preparations may be made by subjecting the latter to heat, and by soaking the former in water, then proceeding in the usual manner for mounting arthropods. The Mallophaga (suborders Amblycera and Ischnocera) are obligatory parasites: their life cycle must be spent entirely on the host. Their metamorphosis is incomplete. The forms which parasitize birds lay their eggs on feathers. The author has observed that the eggs of at least ten species (six genera) are distinctive with respect to size, shape, cap pattern, and position and method of attachment. Females probably remain fertile for life (one female was observed to lay fertile eggs for a period of 30 days after her mate had died). In general, the Amblycera possess squat bodies, are quick runners, are usually found between the skin and the quill, and often have red intestines, indicative that blood makes up part of their diet (Boyd, 1951). The Ischnocera have relatively narrow bodies, their intestines are never red,
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