Population genetics and genotyping for mark-recapture studies of Northern Goshawks (Accipiter gentilis) on the Kaibab Plateau, Arizona

Advances in molecular techniques have facilitated use of genetic data in demographic wildlife studies. An important first Step in genetic mark-recapture is selecting markers that uniquely "mark" and reliably "recapture" individuals. Markers should be tested on reliable DNA from known individuals (blood) before being used on non-invasively sampled DNA (hair, scat, or molted feathers). To evaluate whether Northern Goshawks (Accipiter gentilis) can be uniquely identified by genotyping, 113 known (banded, sexed) goshawks from the Kaibab Plateau, Arizona, were genotyped using DNA from blood and five microsatellite markers and a sex-linked gene. We used mean relatedness to test whether adults in the population were related and probability of identity (P-(ID) = probability that two random individuals from the population have the same genotype) to test the ability of multi-locus genotyping for uniquely identifying goshawks. We used genetic data to assess inbreeding and demographic data to estimate the effective population size. Sixty-nine adult goshawks were sexed correctly and genotyped. Expected heterozygosity was high (H-E = 0.81), and relatedness among adult, was low (r = -0.017). All individuals sampled (69 adults, 44 nestlings) had unique five-locus genotypes, the overall probability of identity was low (P-(ID)unbiased = 7.03 X 10(-7)), and the observed P-(ID) was <0.0001. Thus, Kaibab goshawks were uniquely "marked" by genotyping. Despite a small effective population size (N-e, = 37 individuals), goshawks on the Kaibab Plateau functioned as a large breeding population with no inbreeding (F-IS = -0.001). We hypothesized that genetic diversity is maintained by gene flow via immigration of individuals from distant forests.