Nest-Site Fidelity and Dispersal of Gyrfalcons Estimated by Noninvasive Genetic Sampling

Abstract

We used feathers from adult Gyrfalcons (Falco rusticolus) molted in breeding territories and blood samples from nestlings to document nest-site fidelity and dispersal of breeding adults and juveniles at three areas 100-350 km apart in Yukon Delta National Wildlife Refuge, Alaska, 2003Alaska, -2007. We used genotypes from seven polymorphic microsatellite loci that provided a mean probability of identity of 0.91 xlO'. Breeding Gyrfalcons were highly faithful to study area and territory; we documented no dispersals of breeding birds among study areas and only one dispersal between territories. But their fidelity to nest sites was low; 22% of birds returned to the same nest site the following year Distance among alternate nests within a territory averaged 750 m and was similar for both sexes. Mean tenure in a territory was 2.8 years, similar for both sexes, and distributed bimodally with peaks at 1 and 4 years. Mean annual turnover rate at the Ingakslugwat Hills (Volcanoes) study area was 20%. We detected three young that established breeding territories at distances ranging from 0 to 254 km from their natal territory, representing 2.5% apparent recruitment. Gyrfalcons in the Askinuk Mountains study area were slightly but statistically significantly differentiated genetically from those in the Volcanoes and Kilbuck Mountain study areas. These data are the first published on the nest-site fidelity, breeding dispersal, and natal dispersal of the Gyrfalcon in North America and demonstrate the utility of noninvasive genetic sampling to greatly improve our understanding of avian dispersal and its underlying mechanisms.

Noninvasive genetic sampling reveals intrasex territoriality in wolverines

“…A few studies have assessed territory turnover in raptors using noninvasive genetic sampling by collecting and genotyping shed feathers (Booms et al. ; Vili et al. ).…”

Developing Gyrfalcon Surveys and Monitoring for Alaska.

“…Furthermore, Gyrfalcons in the three study areas returned to nest in the study area in which they were first detected breeding, with no detected breeding dispersal and only one case of natal dispersal among the areas (Booms et al 2011a). These results suggest that additional sampling should be conducted to ascertain the extent of genetic structure among Alaskan Gyrfalcons.…”

“…Further, Booms et al (2008bBooms et al ( , 2011a) studied nest site fidelity and dispersal. The results of these projects are the basis for developing a strategy to monitor Gyrfalcons in Alaska.…”

Genetic structure confirms female-biased natal dispersal in the White-tailed Eagle population of the Carpathian Basin

“…Therefore, instead of conventional methods, genetic data recovered from non-invasive samples are increasingly used to investigate several topics of individual-based studies, such as annual turnover rate of breeding individuals, parentage, breeding dispersal, or territorial intrusions (Rudnick et al 2005, Booms et al 2011, Vili et al 2013b, Nemesházi et al 2018. Straightforward methods for investigation of natal dispersal require knowledge on both the hatching and first breeding place of the sampled individuals.…”