WASHINGTON (AP) — A new United Nations report says nearly half of the world’s migratory species are in decline.

Many songbirds, sea turtles, whales, sharks and other migratory animals move to different environments with changing seasons.

They face threats including habitat loss, illegal hunting and fishing, pollution and climate change.

The U.N. report released Monday found 44% of migratory species worldwide are declining in population.

More than a fifth of species monitored by the U.N. are threatened with extinction.

The report relied on existing data including from the International Union for Conservation of Nature’s Red List, which tracks whether a species is endangered.