Avid bird-watchers looking for accuracy in Hollywood movies are bound to be disappointed. The birds we see on screen in films set in the U.S. are bound to be exotic species, rather than natives. It’s not just laziness—it’s the law. Since 1918, the Migratory Bird Treaty Act has prohibited people from possessing migratory birds for any commercial purpose, as The Washington Post points out today. Buying or selling a domestic bird is a felony—putting a damper on the use of birds in movies.

Writer Nicholas Lund expounds:

American bird species are almost never seen in American film or TV. Those vultures seen in the 2013 film ‘The Lone Ranger,’ set in Texas? They’re an African species. The doves in ‘Dances With Wolves?’ Ringed turtle-doves, also not found in the wild outside of Africa. The CGI’d raven in this year’s Oscars nominee for best picture, The Revenant? I don’t know what that was, but it sure wasn’t something native to this country.

Instead of using a familiar American bird like a blue jay or a blackbird, filmmakers have to make do with a similar-looking bird that isn’t native to the States, sourcing avian actors from exotic bird breeders.

While this may feel restrictive to a director’s vision, the law has been instrumental in protecting American bird species. It was one of the very first American laws on the books that sought to protect a specific type of wildlife from exploitation. It now protects more than 1000 species of birds. According to Audubon magazine, “the MBTA has saved millions, if not billions, of birds from depredatory human activities.” And thus, an American bird will never have the chance to become a movie star.

[h/t The Washington Post]