There are few true Arctic specialist birds that remain in the Arctic throughout their annual cycle. They include the willow and rock ptarmigan (Lagopus lagopus and L. muta), gyrfalcon (Falco rusticolus), snowy owl (Bubo scandiacus), Arctic redpoll (Carduelis hornemanni) and northern raven (Corvus corax)—a cosmopolitan species with resident populations in the Arctic. All other terrestrial Arctic-breeding bird species migrate to warmer regions during the northern winter, connecting the Arctic to all corners of the globe. Hence, their distributions are influenced by the routes they follow. These distinct migration routes are referred to as flyways and are defined by a combination of ecological and political boundaries and differ in spatial scale. The CBMP refers to the traditional four north–south flyways, in addition to a circumpolar flyway representing the few species that remain largely within the Arctic year-round (Figure 3-20).

STATE OF THE ARCTIC TERRESTRIAL BIODIVERSITY REPORT - Chapter 3 - Page 48- Figure 3.20