HYBRIDIZATION AMONG BUTEOS: SWAINSON'S HAWKS (BUTEO SWAINSONI) X RED-TAILED HAWKS (BUTEO JAMAICENSIS).

We report three cases of hybridization between wild Swainson's Hawks (Buteo swainsoni) and Red-tailed Hawks (B. jamaicensis) identified by using nuclear and mitochondrial DNA markers. The hybrid individuals were field-identified as Swainson's Hawks and sampled from Alberta. Canada (n = 2) and Utah, USA (n = 1). Nineteen nuclear microsatellite loci were used in a factorial correspondence analysis to create genotypic clusters of 468 Red-tailed and 357 Swainson's hawks. Three suspected hybrids were identified by an intermediate genetic position between the genotypic clusters of the two species, indicating a hybridogenetic composition. We examined mitochondrial control region sequence data to identify the maternal background of the putative hybrids: two of the hybrid specimens had Red-tailed Hawk mtDNA haplotypes and the third a Swainson's Hawk haplotype. These results suggest that hybridization between these two species may occur in their shared breeding range and can result in reciprocal hybrid offspring, barring any social, behavioral, or biological isolating mechanisms. [ABSTRACT FROM AUTHOR]