Nearly half of the world’s migratory species are in decline, according to a new United Nations report released on Monday.

Many songbirds, sea turtles, whales, sharks and other migratory animals move to different environments with changing seasons and are imperiled by habitat loss, illegal hunting and fishing, pollution and climate change. About 44 per cent of migratory species are declining in number. More than a fifth of the nearly 1,200 species monitored by the U.N. are threatened with extinction.