New analysis on the place peregrine falcons hibernate
Two studies published in the September 2020 issue of the Journal of Raptor Research have expanded our understanding of peregrine falcon migration and population stability.
The first report by Oscar Beingolea and Nico Arcilla of the International Bird Conservation Partnership reports that peregrine falcons at their North American breeding sites, birthplaces, or during migration have all flown to Peru for the winter.
Eight hawks that were banded at breeding grounds from Alaska to Nunavut to Minnesota and Nebraska between 1963 and 2016 were later found at sites in Peru, the study shows. And 13 hawks gathered at migration sites in Texas and along the east coast also appeared in Peru. An Alaska bird traveled the furthest – 10,671 km.
The results suggest that falcons from two subspecies, Falco peregrinus tundrius and F. p. anatum, "winters in Peru and come from a widespread geographic breeding area, confirming other research suggesting that migratory migration in the Nearctic is very dispersive," the researchers write.
The second study looked at the stability of the migrant population along the Pacific coast in the southwestern part of Washington state. A team of researchers led by Daniel E. Varland captured and banded Peregrines from 1995 to 2018.
Based on years of follow-up studies of falcons on the beaches in the area, Varland and colleagues say that the birds “have relatively high levels of survival, which indicates good population performance. This is confirmed by our finding that the peregrine falcon observation rate was stable over the 22-year study. "
The researchers note that other observers reported more falcon reconnaissance starting in 2008, a year that coincided with the "advent of digital cameras in wildlife photography and public awareness of our project in those years".
Varland also reports that mercury levels in migrant feathers were "among the highest reported for the species" in his study, but that pollutant levels appeared to affect survival.
Species profile: Peregrine falcon observation and study at Rankin Inlet, Nunavut, Canada
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