From African elephants searching for water, to turtles crossing seas to nest, and to albatrosses on their ocean-spanning search for food, the world's migratory species are under threat across the planet, according to a landmark report Monday.
The first-ever State of the World's Migratory Species assessment, which focusses on the 1,189 species covered by the UN Convention on the Conservation of Migratory Species of Wild Animals (CMS), found that one in five is threatened with extinction and 44 percent are seeing their populations decline.
Humans are to blame, by destroying or breaking up habitats, hunting, and polluting areas with plastics, chemicals, light and noise.
Climate change also threatens to interfere with migration routes and timings, by altering seasonal conditions.
"We are finding out the phenomenon of migration itself is under threat," CMS chief Amy Fraenkel told AFP, adding that the report should be a "wake up call about what's happening".
Migratory species often rely on very specialised sites to feed and mate and their journeys between them can cross international borders and even continents.
Iconic species that make some of the most extraordinary journeys across the planet include the monarch butterfly, the humpback whale and the loggerhead turtle.
"There is a big gap that we've now identified that needs action," she said.