Examination of Climate Effects on Host-Parasite Dynamics in Burrowing Owls and Fleas

Ectoparasites of raptors include lice, ticks, flies, and fleas. One interesting host-parasite relationship occurs between Western Burrowing Owls (Athene cunicularia hypugaea) and Pulex irritans (Family Pulidae), the so-called human flea. Fleas are hematophagous insects that sometimes infest birds, but this particular association is unusual because P. irritans typically parasitizes mammals such as carnivores, ungulates, and rodents. Moreover, the association between Burrowing Owls and P. irritans occurs only in the Pacific Northwest of the United States, even though both species have broader distributions. Molecular studies have confirmed that P. irritans feeds from Burrowing Owls, so owls are not simply a phoretic host for P. irritans. Factors that influence spatial and temporal variation in flea prevalence and intensity including climate effects have rarely been examined. Because fleas are susceptible to dessication, are there more fleas present in years with higher rates of precipitation and in years with cooler temperatures? And does climate affect host-parasite relationships similarly in human-modified landscapes as in non-agricultural lands? Our poster explores these questions and others using long-term data about flea prevalence and intensity collected between 1997-2019 from a population of Burrowing Owls breeding in Southern Idaho