Gyrfalcons as an Indicator of Emergent Diseases in a Rapidly Changing Arctic Ecosystem

Disease causing pathogens are integral ecosystem components that can have profound effects on populations. Temperature and moisture are fundamental predictors for pathogen distribution and climate change is facilitating the northern encroachment of novel diseases, exposing naïve Arctic species to uncertain risks. The Gyrfalcon (Falco rusticolus), due to its status as an Arctic specialist, resident, and top predator, can serve as an effective indicator for disruptions within Arctic ecosystems and their vulnerability to novel diseases should make them particularly effective sentinels for disease ecology. Here we aim to delineate Gyrfalcon diseases by performing molecular and immunological testing on biological samples collected 2004 – 2022 in Alaska, USA (Yukon-Kuskokwim Delta, Seward Peninsula, and Cold Bay), to better understand occurrence and prevalence of disease and how it may be changing temporally. Further, migratory prey may transmit more novel diseases, thus we are trapping free-flying Gyrfalcons (adults and juveniles) that are hunting primarily migratory waterfowl, which serve as reservoir hosts for important diseases. Preliminary serology results indicate previous exposure to salmonella in 94% of tested Gyrfalcons, avian influenza (presumably low pathogenic) in two nestlings and one juvenile, and adenovirus in two juveniles. All tested birds were negative for west Nile virus and chlamydia. Analysis of fecal samples from 2021 indicated that 83% of nestlings hosted coccidia parasites with various levels of infection and one juvenile tested positive for porrocaecum. Further, we observed plaques in the oral pharynx of one nestling and numerous juvenile Gyrfalcons, which were likely capillaria (Eucoleus contorta) or trichomonas (Trichomonas gallinae), both of which can be fatal. To our knowledge, this is the first effort to delineate diseases in North American Gyrfalcons and results will serve as a baseline that could have important implications for Gyrfalcon conservation and highlight changes to Arctic disease ecology during rapid climatic and ecosystem change.