Widespread lineage diversity of leucocytozoon blood parasites in distinct populations of western Red-tailed Hawks

This study examines the relationship between genetically distinct populations of Red-tailed Hawks (Buteo jamaicensis) with hemosporidian parasite phylogenetic data to examine geographic structuring of parasite lineages and to test for impacts of parasitic infection on host migration timing. We screened 296 hatch-year Red-tailed Hawks for infection with hemospridian parasites of the genus Leucocytozoon at a raptor migration site in the Marin Headlands, California, just north of San Francisco. Phylogenetic analysis based on cytochrome b sequences revealed a high diversity of closely related Leucocytozoon buteonis lineages (11 distinct haplotypes recorded) infecting the sampled hawk populations. Previous microsatellite analyses of breeding and migratory populations of Red-tailed Hawks revealed that the Marin Headlands migrants originate from two genetically distinct breeding populations from Central California and the Intermountain West. Early hawk arrivals to the study site (15 August-30 September 2004) are primarily non-migrant juveniles dispersing from Central California, while later arrivals (1 October-30 December 2004) are a mix of both California dispersals and migratory individuals from the Intermountain West population. We observed no correlation between the occurrence of parasitic infection and hawk migration timing in either hawk population. However, geographic structuring of Leucocytozoon parasite lineages was documented with one dominant lineage more prevalent within the Central California hawk population than the Intermountain West population. Future studies of the effects of Leucocytozoon infection on migrating Red-tailed Hawks should take into consideration the region of origin because birds from different geographical areas may be exposed to distinct parasite lineages.