Date of Award:


Document Type:


Degree Name:

Doctor of Philosophy (PhD)



Department name when degree awarded


Committee Chair(s)

Wilford J. Hanson


Wilford J. Hanson


Kenneth J. Capelle


Curtis W. Sabrosky


The host, habitat preferences, and life histories of species of Protocalliphora were investigated in northern Utah. The effect of species of Protocalliphora on blood levels (hematocrit and hemoglobin) and weight gains of nestling birds also was studied.

A total of 1,819 bird nests were examined, representing 68 bird species from 10 habitats. Forty-eight percent (869) of the nests of 51 bird species found were infested. Eighteen species of Protocalliphora, including 11 undescribed, were collected.

Birds experiencing a high rate of infestation included most colonial nesters (such as bank swallows and yellow-headed blackbirds), cavity nesters (such as starlings and tree swallows, excluding woodpeckers), and some solitary open nesters, such as magpies, warblers, and flycatchers. Many solitary open nesters (such as sparrows and robins) and one colonial nester (red-winged blackbirds) experienced lower rates of infestation.

Two species, f. chrysorrhoea and f. hirundo, appeared to be specific to their hosts, bank swallows and cliff swallows, respectively. Several undescribed species had narrow host or habitat preferences, including the dominant species infesting warblers and flycatchers, and a species infesting only marsh birds. One rare species (undescribed) was found primarily in the nests of Falconiformes. f. asiovora infested many bird species, but was the dominant species infesting Corvidae (magpies, ravens and crows). f. sialia occurred in the nests of many species, but favored cavities.

Multiple infestations, involving more than one species of Protocalliphora in a nest, were found in 7.1% of the infested nests examined. Brewer's blackbirds and five species of swallows commonly experienced mixed infestations, especially those nesting in peripheral habitats. Only r. hirudo was regularly involved in mixed infestations.

Life history studies were conducted and developmental periods were determined for larvae and pupae of five species of Protocalliphora. Behavioral observations were made on larvae and adults in the field and laboratory.

The effect of larval blood-sucking on nestling magpies and bank swallows was determined by comparing rates of weight gain (only in magpies) and blood levels (hemoglobin and hematocrit) between infested and uninfested nestings. Although the number of fledged nestlings was not reduced substantially in heavily infested nestlings, they did experience significantly lower rates of weight gain and blood levels. Blood levels also were examined in infested and uninfested starlings, kestrels, and yellow-headed blackbirds. Of these, only starlings experienced infestations large enough to cause significant reductions in blood levels.

Factors regulating larval populations of P. asiovora in magpie nests also were investigated. The relative importance of predation and interspecific and intraspecific competition in regulating larval populations was considered. Although several factors appeared to be interacting, intraspecific competition appeared to be the most important regulatory factor.



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