Use of genetic techniques to address biases in northern goshawk turnover metrics

The Northern Goshawk is listed as a management indicator species for the Minidoka Ranger District of the Sawtooth National Forest. This distinction has enhanced research interest on goshawk population health in the region. For raptors, annual adult turnover is considered a crucial metric of population health; providing insights into mortality, fidelity, and population disturbances. Over the past 25 years of studying goshawks, the Intermountain Bird Observatory (IBO) has observed abnormally high female turnover as compared to other places the species has been studied. Their estimations are based on banding and resighting birds, and may be biased high due to undetected marked birds and unknown age of birds when banded. To increase accuracy of IBO’s turnover data, we conducted parentage analyses using blood samples collected from goshawks in 2012-2016. We analyzed 32 samples from nine nest territories by examining shared alleles between adults and nestlings. With this analysis, we identified previously unknown turnover and fidelity events, increased known ages of banded birds, and quantified and removed bias from IBO’s turnover estimations. Our work indicated that band-resight alone may be insufficient to produce accurate turnover estimates, and the inclusion of genetic analyses may mitigate inaccuracies. In addition, our results fundamentally altered IBO’s understanding of goshawk population dynamics within the forest