Conservation and Management

Effects Of Human Activity

Not particularly aggressive when humans intrude on nest site, often slipping away and circling silently, though individual birds vary in degree of aggressiveness (Cade 1982). Some pairs become habituated to presence of humans on foot, at least at distances of 300 m (Platt 1977, Poole and Bromley 1988b). Improper approach to nest, however, can cause exposure, injury, or death of nestlings (Bromley 1986). In Yukon, birds were always disturbed by helicopter overflights at 150 m above nest site, less frequently disturbed at 300 m, and not disturbed at 600 m; birds were more disturbed by lateral approaches than approaches from above (Platt 1976); may attack fixed-wing aircraft (C. M. White pers. comm.). Disturbance from overflights did not result in abandonment or reduced productivity, but disturbed birds were less likely to reuse same nest site following year (Platt 1977).

Gyrfalcons may be negatively affected by radio and satellite backpack transmitters. One adult female temporarily abandoned its nest and regularly fought with its harness for a week after transmitter deployment, though it successfully fledged young (TLB). Of 11 fledglings and 3 breeding adults harnessed with approx. 30-g transmitters in w. Alaska, none were detected alive the following breeding season except for one adult that had removed its transmitter harness. One adult and 1 fledgling were confirmed dead the spring after deployment; fates of the remaining birds unknown (TLB unpub. data). No definitive data available on effects of transmitters on Gyrfalcons, but scant information available and field observations of harnessed birds suggests birds negatively affected.

Although shooting is a significant cause of mortality in Iceland (Clausen and Gudmundsson 1981, Nielsen and Cade 1990b), there is no information on the incidence of shootings in North America; presumably there would be fewer as North American Gyrfalcon populations are more isolated from human populations (Shank and Poole 1994). Little mortality caused by accidental capture in ptarmigan or fox traps in N. America, although this appears to be a significant source of mortality in Russia (Orden and Paklina 2000, Potapov and Sale 2005).

DDT contaminant levels were generally low in North American Gyrfalcons, almost an order of magnitude lower than those of arctic Peregrine Falcons, although levels of some individuals approached those of Peregrines (Cade et al. 1971, Walker 1977). Because most Gyrfalcons are resident, live in areas remote from pesticide use, and feed on non-migratory prey, they are generally less susceptible to contamination than the migratory Peregrine. Eggs and lipids of Alaskan Gyrfalcons contained both DDE (0–290 ppm) and PCBs (5.7–210 ppm) (Cade et al. 1971, Walker 1977). Eggs of birds from Northwest Territories (NWT) contained low levels of DDT, DDE, PCBs, oxychlordane, dieldrin, heptachlor epoxide, and aroclor 1254/126 (Bromley 1986, Poole and Bromley 1988b). Levels of DDE and PCBs in tissues of resident prey species insufficient to account for higher levels of contaminants observed in some individuals. Migratory prey species such as shorebirds had 10–100 times contaminant levels of resident species and probably account for higher levels of contaminants in some individuals (Walker 1977). In Greenland, where both predator and prey are resident, DDE was the only contaminant found in plasma; not found in all samples, and occurred at lower levels (< .02 ppm wet weight; Jarman et al. 1994). Icelandic ptarmigan had low levels of organochlorine contamination compared to migratory or marine-associated avian prey species (Olafsdottir et al. 2001). No eggshell thinning or other effects on reproduction noted (Cade et al. 1971, Walker 1977).

Gyrfalcon mercury levels in Europe (1.72 ± 3.35 ppm) also lower than in Peregrine Falcons (17.6 ± 6.99 ppm). Mercury levels higher in migratory (aquatic) prey, particularly shorebirds, and in Gyrfalcon nestlings fed a greater proportion of aquatic species (Lindberg 1984). Lower levels of platinum group elements and organochlorines in Gyrfalcons compared to other raptors in Europe as well (Herzke et al. 2002, Jensen et al. 2002, Ek et al. 2004). Gyrfalcons in Greenland had lower mercury levels than Peregrine Falcons or White-tailed Eagle (Dietz et al. 2006). Overall, Gyrfalcons have low levels of contamination; those consuming migratory, marine-feeding, or insectivorous avian prey have higher contaminant loads than those relying on resident ptarmigan populations.

Habitat modification, egg collection, and falconers have all been blamed for population declines in Scandinavia and adjacent portions of Finland and Russia (Cramp and Simmons 1980, but see Cade et al. 1998 for evaluation), and removal of wild birds to commercial markets may threaten some populations in Russia (World Working Group on Birds of Prey 1992, Potapov and Sale 2005). Remoteness of breeding sites in North America has prevented such factors from negatively influencing these populations. Human populations and Gyrfalcon populations are not necessarily incompatible, however, as shown by high density of birds in Iceland, where the breeding population endured a loss of about 25% of its annual population (owing to export of birds to Europe) in prior centuries without long-term decline, and where much of habitat is overgrazed (Cade 1982, Nielsen and Pétursson 1995).

Most significant current and likely future effects of human activity on the Gyrfalcon are those of global warming. Although research in this field is just beginning and the current effects on Gyrfalcons can only be surmised by correlations (The Peregrine Fund 2005a), birds and other fauna are extending their distributions northwards and spring events are occurring earlier in concordance with documented climatic warming (Thomas and Lennon 1999, Parmesan and Yohe 2003, Hitch and Leberg 2007). The tundra landscapes to which Gyrfalcons are adapted are undergoing habitat change through shrub expansion in Alaska, Canada, and likely across the circumpolar Arctic (Sturm et al. 2001, Tape et al. 2006). From 1949-1998, mean annual temperatures in Alaska have increased up to 2.2° C (Stafford et al. 2000). The Gyrfalcon will likely be affected by these changes through numerous direct and indirect pathways. Likely candidates include range constriction, changes in diet and breeding phenology, shrinking foraging habitats, thermal stress, increased human access to and disturbance of nests, extreme weather events affecting survival and nesting, and interspecific competition.

Management

No active management in North America. A few independent, long-term monitoring projects in parts of Greenland, Canada, and Alaska, though not coordinated.

The Gyrfalcon is protected in both Canada and the U.S. but is not listed as endangered or threatened. Because of the species’ use in falconry and its associated value in foreign markets, however, its status has been controversial. North American populations were initially listed under Appendix I of C.I.T.E.S. (normally reserved for endangered species; prohibits import and export for commercial purposes) but were moved to Appendix II in 1981. In 1985, despite Canadian opposition, they were moved back to Appendix I in response to a proposal by Norway and Denmark, which had noted declines in Palearctic populations (Parrish and White 1987). Management of North American falcons is under state and provincial jurisdiction, but in Canada’s 4 western provinces and 2 territories it is coordinated through the Western Raptor Committee, comprised of representatives from wildlife agencies from each jurisdiction.

There have been two Canadian attempts to manage the Gyrfalcon as a renewable wildlife resource for use in falconry: in the Yukon (Mossop and Hayes 1982) and in the Northwest Territories (Bromley 1986). Although biologically justifiable, these programs have met with limited success owing to political difficulties. Meanwhile, captive propagation has provided an increasing number of Gyrfalcons for falconry. Since the first Gyrfalcons produced by The Peregrine Fund at Cornell University in 1974 (Cade 1986), many hundreds of Gyrfalcons have been reared by a number of private breeders in Canada and the U.S., and many more in Europe. Most Gyrfalcons now flown in North American falconry are captive-produced birds. Legal, regulated harvest of wild-caught immatures, however, does occur, for noncommercial use only, in several states/provinces and likely has little or no impact on population viability.