Some of the spectacular migration routes followed by migratory bird species

Birds are arguably the most mobile creatures on Earth, rivalling even humans. They show morphological, physiological and behavioural adaptations that allow them to fly high, fast and for extended periods during their epic journeys. For its pole to pole journey, Arctic Tern Sterna paradisaea reigns supreme, being the only bird known to migrate between the Arctic and Antarctic. Electronic tagging of Arctic Terns has revealed average annual travel distances of 70,900 km (range 59,500–81,600 km) for birds nesting in Iceland and Greenland (Egevang et al. 2010), while one bird nesting on the Farne Islands flew an estimated 96,000 km—the longest flight ever recorded for a migratory bird (Newcastle University, 2016). Following a close second, the Sooty Shearwater Puffinus griseus can clock up an incredible 64,000 km (± 9,779 km) during its annual migration around the Pacific Ocean (Shafer et al. 2006). Bar-tailed Godwit Limosa lapponica shows remarkable endurance and holds the record for longest non-stop flight of nearly 13,000 km (Holmes 2008, Gill et al. 2008, Global Flyway Network 2020). To sustain flight for so long without feeding requires remarkable physiological adaptations and Bar-tailed Godwits set off with more than half their body weight made up of fat, while incredibly their gut shrinks to make way for the extra fat and muscle (Piersma and Gill 1998).

Other migrant species are not outshone. Bobolink Dolichonyx oryzivorus flies more than 9,600 km, from the prairies of Canada to the pampas of Argentina. Far Eastern Curlew Numenius madagascariensis travels the length of East Asia from its breeding grounds in Siberia to the coasts of Australia, with female birds continuing even further south to wetlands in south Australia. Short-tailed Shearwater Puffinus tenuirostris undertakes an incredible figure-of-eight circuit of the Pacific Ocean, the circumpolar Cape Petrel Daption capense ranges extensively across the Antarctic region, while Amur Falcon Falco amurensis makes a massive loop between East Asia and South Africa. European Bee-eater Merops apiaster winters exclusively in Africa with west European birds moving to west Africa and east European ones heading down the Nile to southern Africa—one individual ringed near Moscow was recorded in Zimbabwe, nearly 8,000 km away. These seven species illustrate some of the major migration pathways flown by the thousands of long-distance migrant bird species (see figure).

Besides their aesthetic value, migratory birds are important in numerous cultures (e.g. as harbingers of season shift), provide a major resource when managed sustainably for food or sport, are environmental indicators, and link developed and developing countries (Salathé 1991). Common concerns for the threats faced by migratory birds, plus the recognition that conserving them is an international duty, underpin collaborative international legislation and conventions. For instance, the Convention on Migratory Species aims to conserve terrestrial, marine and avian migratory species throughout their ranges. By fostering bonds among nations, migratory birds act as valuable ambassadors for our shared natural heritage.