Just a few quick links:
From BBC Nature, this report on gyrs (east Greenland gyrs, anyway) as "secret seabirds", spending much of the winter on ice floes in the open ocean. While it has long been known that gyrs in coastal areas prey on seabirds, the species as a whole is considered to be dependent on ptarmigan—their ranges (omitting the new data from Kurt Burnham and Ian Newton) are almost entirely co-extensive. Apparently, however, some gyrs may specialize in seabirds year-round, not just when they are concentrated at rookeries during the breeding season.
Speaking of gyrs and ptarmigan, The Peregrine Fund hosted a conference last year on how climate change might affect the gyr and its prey species. This link is essentially an announcement of the conference, but I'm hoping it will eventually be updated to include the proceedings.
And here is the best of several gyrfalcon posts by Clare Kines at his blog, The House and other Arctic musings, which I am duly adding to my blogroll. HT Luisa at Lassie, Get Help.