Flyways

Every year, billions of birds migrate vast distances across the globe. There is a wide array of different migratory strategies and a lot of variability in routes taken between species, and between individuals within a species or population. Amid that complexity emerge some broad patterns, which have led to the recognition of four “flyway systems” in the terrestrial realm. Some of these flyway systems are further split into recognised ‘flyways’. BirdLife International currently recognises eight flyways in the terrestrial realm (used by land and waterbird species) and six flyways in the marine realm (used by seabird species).

The flyways recognised in the terrestrial realm are broad schematic delineations which, between them, contain the majority of migratory species movements, with each flyway encompassing all stages of the annual cycle (breeding, passage and non-breeding areas). Breeding and non-breeding areas may be used by migratory species for several months at a time, while passage areas may be used for shorter periods as the birds rest and refuel on their migration.

Some migratory waterbirds, raptors, seabirds, and other species congregate in large numbers in specific areas within their flyways or as they pass through ‘bottlenecks’ where their route is constrained by physical features. Other species migrate on a ‘broad front’, or dispersed manner.

Much migration of land and waterbirds occurs in a north-south direction, but there are also examples of east-west migration. Seabirds make movements influenced by the availability of resources and prevailing winds, including complex figure of 8 migrations in the Atlantic and Pacific Oceans. Knowledge gaps are being filled all the time and tracking technology is delivering important insights. The six marine flyways have been identified through analysis of tracking data for more than 1000 seabirds of 48 long-distance migratory species, facilitated through the Seabird Tracking Database.

Many of the world’s migratory bird species are in decline and they may face many different threats at different points in their annual cycles, so understanding and addressing the drivers of declines requires flyway-scale understanding and action. Habitat loss and degradation can have a significant impact on the ecological networks of areas of suitable habitat migratory birds rely upon throughout their flyways. The cumulative impact of direct mortality from causes such as hunting, illegal killing, or bycatch operating at many different points along a flyway can have a negative impact at population scale. Poorly placed energy or other infrastructure at sensitive points within flyways can have a disproportionately negative impact. For migratory species, lack of action to address threats in one part of the flyway can undermine conservation effort and investment elsewhere in the flyway, so the conservation of migratory birds depends on international collaboration and a coordinated response throughout entire flyways. Through BirdLife’s Global Flyways Programme the BirdLife partnership works together and in coordination with other stakeholders to improve the outcomes for migratory bird species.