The detailed methods developed to identify marine flyways from seabird tracking data have been described in a new paper published in Global Ecology and Biogeography. The six marine flyways, presented by BirdLife International, follow the major routes seabirds travel along as they migrate across vast areas of the world’s oceans.
Infographic highlighting the six marine flyways and their connectivity within the world’s oceans. A Spilhaus projection is used in the map. By Science Animation Studio
How were the marine flyways identified?
To complement the existing terrestrial and coastal flyways, we focused on long-distance, pelagic migrants – defined here as species that travelled >2000 km from their breeding colony for a minimum of 30 days, and took routes that were primarily in oceanic areas beyond national jurisdiction. We requested tracking data through the Seabird Tracking Database and collated data from 48 seabird species spanning several decades, which were collected by more than 100 researchers who contributed to the project.
We analysed locations recorded during migration and separated the outbound and return routes, because some individuals follow different routes to and from their breeding colonies. We assigned individual outbound and return migrations to one ocean basin (Atlantic, Indian, Pacific or Southern) and analysed each ocean basin separately. [Note that migrants that use the Arctic Ocean were assigned to the Atlantic or Pacific as appropriate.]
We applied a dynamic time warp cluster analysis to group migration routes based on similarities of the pathway independently of the timing of migration and the population/species. The outputs of the cluster analysis (2–5 clusters of individuals with the most similar migratory routes) were visualised using the line density tool (ArcGIS). [In the Southern Ocean no cluster analysis was performed as a literature search indicated that only one flyway would be present.] We extracted raster layers from the line density outputs and combined any clusters that were clearly linked through full migratory journeys.
Figure 2 from Morten et al. 2025 – three key migratory route clusters in the Atlantic Ocean, which were combined to form the Atlantic Ocean Flyway
The major flyways were derived from the clusters through a semi-quantitative approach that incorporated prior knowledge of seabird migration and ensured that the outputs aligned with the broad intentions of the marine flyways. More details are available in the paper, and the code is provided.
The six marine flyways
In both the Atlantic and Pacific oceans, large figure-of-eight flyways were identified, spanning both hemispheres. The West Pacific Flyway encompasses more coastal migratory routes. The North and East Indian Ocean flyways span from colonies in the west Indian Ocean northwards into the Arabian Sea and eastwards towards Indonesia and Australia respectively. The Southern Ocean Flyway formed a circumpolar ring around Antarctica, generally followed in a clockwise direction, corresponding with prevailing winds.
Figure 1 from Morten et al. 2025 – six marine flyways, which were delineated from seabird tracking data. Black squares indicate the colonies where the tracked individuals breed.
The marine flyways are used bidirectionally, and throughout the year. Within each flyway some individuals follow the entire route, such as Grey-headed Albatross in the Southern Ocean Flyway. Some individuals migrate through sections of a flyway, such as Antipodean Albatross which travel eastwards below 25°S, from colonies off the coast of Aotearoa New Zealand into the Humboldt Current. Some migrate through multiple flyways, such as Arctic Terns that migrate through the Atlantic Ocean Flyway, into the East Indian Ocean Flyway and then move south into the Southern Ocean Flyway. In some cases, the same population use different flyways, such as South Polar Skuas breeding on King George Island, Antarctica – some individuals migrate into the Pacific Ocean Flyway, and others into the Atlantic Ocean Flyway.
What’s next for the marine flyways?
Seabirds are one of the most threatened groups of vertebrates, with 30.4% considered globally threatened. Their conservation requires a holistic approach that encompasses their entire range, annual cycle and considers the cumulative effects of threats. For the 76% of seabirds classified as ‘full-migrants’, conservation efforts require coordinated management actions at an ocean-basin scale.
The marine flyways highlight the vast movement patterns across the global ocean and illustrate the connectivity across distant regions. This framework can be used to 1) identify and protect a global network of important areas within the flyways, 2) identify and mitigate emerging threats at key sites and broader scales, 3) more easily identify inter-governmental partnerships and stakeholder collaborations, 4) identify research needs and opportunities. Demonstrating shared ownership of migratory seabirds can facilitate international coordination, and the marine flyways are particularly relevant to multilateral environmental agreements, including the Convention on the Conservation of Migratory Species (CMS), and the forthcoming ‘High Seas Treaty’ (the United Nations Convention on the Law of the Sea and the Conservation and Sustainable Use of Marine Biological Diversity of Areas beyond National Jurisdiction). Ultimately, the marine flyways provide a structure for international cooperation, which is essential to conserve these enigmatic species.
Tracking data used in this study are available to request from the Seabird Tracking Database. The full details of which datasets were used are available in Table S1 of the paper.
The full paper is available here (Morten, J.M., Carneiro, A.P.B., Beal, M., Bonnet-Lebrun, A.-S., Dias, M.P., Rouyer, M.-M., Harrison, A.-L., González-Solís, J., Jones, V.R., Garcia Alonso, V.A., Antolos, M., Arata, J.A., Barbraud, C., Bell, E.A., Bell, M., Bose, S., Broni, S., de L Brooke, M., Butchart, S.H.M., Carlile, N., Catry, P., Catry, T., Charteris, M., Cherel, Y., Clark, B.L., Clay, T.A., Cole, N.C., Conners, M.G., Debski, I., Delord, K., Egevang, C., Elliot, G., Esefeld, J., Facer, C., Fayet, A.L., Fijn, R.C., Fischer, J.H., Franklin, K.A., Gilg, O., Gill, J.A., Granadeiro, J.P., Guilford, T., Handley, J.M., Hanssen, S.A., Hawkes, L.A., Hedd, A., Jaeger, A., Jones, C.G., Jones, C.W., Kopp, M., Krietsch, J., Landers, T.J., Lang, J., Le Corre, M., Mallory, M.L., Masello, J.F., Maxwell, S.M., Medrano, F., Militão, T., Millar, C.D., Moe, B., Montevecchi, W.A., Navarro-Herrero, L., Neves, V.C., Nicholls, D.G., Nicoll, M.A.C., Norris, K., O’Dwyer, T.W., Parker, G.C., Peter, H.-U., Phillips, R.A., Quillfeldt, P., Ramos, J.A., Ramos, R., Rayner, M.J., Rexer-Huber, K., Ronconi, R.A., Ruhomaun, K., Ryan, P.G., Sagar, P.M., Saldanha, S., Schmidt, N.M., Schultz, H., Shaffer, S.A., Stenhouse, I.J., Takahashi, A., Tatayah, V., Taylor, G.A., Thompson, D.R., Thompson, T., van Bemmelen, R., Vicente-Sastre, D., Vigfúsdottir, F., Walker, K.J., Watts, J., Weimerskirch, H., Yamamoto, T. and Davies, T.E. (2025), Global Marine Flyways Identified for Long-Distance Migrating Seabirds From Tracking Data. Global Ecol Biogeogr, 34: e70004.)