Hirundo rustica erythrogaster, Boddaert, 1783

Dube, William C., Hund, Amanda K., Turbek, Sheela P. & Safran, Rebecca J., 2018, Microclimate and host body condition influence mite population growth in a wild bird-ectoparasite system, International Journal for Parasitology: Parasites and Wildlife 7 (3), pp. 301-308 : 303

2.2. North American barn swallows ( Hirundo rustica erythrogaster )

Barn swallows are one of the most common birds in the world in terms of both abundance and geographic distribution ( Brown and Brown, 1999). Barn swallows nest in loose social colonies; in this study, group size ranged from one to 35 breeding pairs. Barn swallows nest almost exclusively in human buildings and other structures, including barns, sheds, and infrastructure such as bridges and culverts. Their close association with humans (and relatively large colony sizes) have led researchers to leverage the system to answer a variety of questions within ecology and evolutionary biology ( Møller, 2000; Safran et al., 2005; Scordato and Safran, 2014; Hund et al., 2015a; Romano et al., 2017).

Barn swallows build mud cup nests in which small mud pellets are sewn together with straw and horsehair and typically lined further with feathers. New nests are constructed every breeding season, but barn swallows prefer to use nests from previous seasons in order to minimize breeding delays ( Safran, 2006). Pairs lay 3– 5 eggs per brood and incubate for 12 days. Nestlings typically fledge around 20 days after hatching, but the range is 15–24 days ( Brown and Brown, 1999). Before fledging, they are restricted to their nest site, where they are cared for by both parents.

Previous work on NFM in a Colorado population of barn swallows found that NFM are the most common nest parasite and that they feed primarily on nestlings. Out of 172 monitored nests, 58.1% were infected with NFM, with a mean infection intensity of 101.09 mites. Infections ranged from 0 to up to 1500 mites ( Hund, 2017). Mites in this study were counted in the field as described below, and are an indication of, but not an exact count of, the total NFM population size within the nest.

Barn swallow nests are not only home to NFM, but a variety of other arthropods. Although we do not formally classify the other arthropods encountered in this study, previous work has identified these to include beetles, flies, pseudo-scorpions, spiders, and lice ( Hund et al., 2015b). Although rarely encountered, we placed these other arthropods into a single group for statistical analysis.