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Hot on the heels of fall migration comes Migration, a Universal Pictures animated film debuting this Christmas about a family of Mallard ducks. If you haven't seen a yet, the basic plot goes like this: Though the dad, named Mack, is satisfied with his quiet, safe, and predictable life in a New England pond, the mom, Pam, is eager to show their kids, Dax and Gwen, more of the world. When the Mallards meet a group of migrating ducks with tales of far-off places, Pam persuades Mack to take off for their own family adventure to Jamaica. Their daring trip quickly goes awry, but the experience pushes them to broaden their horizons and make new connections—from street-smart pigeons to tropical macaws—along their way. 

The film, written by Emmy-award winning creator of The White Lotus, Mike White, captures the grandeur of migration with scenic flight sequences of the family over lush landscapes, drawing inspiration from the real bird phenomenon. Roughly 40 percent of bird species migrate seasonally between breeding and wintering habitats; whereas other “resident” species meet their needs around the same home range all year.

For birds that evolved to migrate, the benefit of better access to food or nesting locations improves the overall odds of survival. But as Mack fears, travel is also a risky affair that exposes birds to dangers both ancient and modern, such as hurricanes, predators, habitat loss, and light pollution, to name a few. In the film, Dax and Gwen endure a scary encounter with a pair of Great Blue Herons, known to occasionally . And in New York City, the family contends with traffic and trash—while narrowly avoiding colliding with skyscrapers, a major source of migratory bird deaths. It's no wonder that of the estimated 3 billion birds lost since 1970,  are migratory.

The urge to migrate can even vary within some species and breeding populations, as the Mallard family accurately shows—a phenomenon called “partial migration.” Red-winged Blackbirds, Blue Jays, Red-tailed Hawks, Bald Eagles, Great Blue Herons, Canada Geese, and many other species are partially migratory. And it's not just birds who exhibit this behavior: Butterflies, fish, wildebeests, and rhinos also have partial migrants who stay put year-round.

Most wild Mallards, which are abundant throughout North America, do migrate to some extent during the winter, especially when northern ponds and lakes freeze over. But there’s also a lot of variability among regional populations and even individual birds. “Mallard migration is far more complex than we previously thought,” says Mike Brasher, senior waterfowl scientist at Ducks Unlimited. “Mallards express individual tendencies when it comes to their wintering destinations. In any given year, one duck might migrate to one destination and stay there, while another might roam around their home range.”  Efforts to track birds with radio tags and bands even show that Mallards and other partial migrants often travel east and west, upending long-held paradigms that migrating birds travel only north or south.  

On the whole, scientists don’t quite know why some individuals of a species migrate while others remain residents. Experts have some general theories. In one, dominant or older birds outcompete subordinates for scarce food in winter, forcing those that lose out to migrate to areas with less competition. Another theory points to body size: Smaller birds may be more likely to migrate than bigger, hardier birds.

As larger ducks, Mallards excel at putting on fat, and are the most cold-tolerant dabbling duck—helpful during those winter months if a bird does choose to stick around a chillier locale. “They’re kind of the perfect animal when it comes to adapting to changing conditions,” says Brasher. Wild Mallards have also interbred with resident feral ducks, potentially affecting the migration behavior of these hybrid birds. 

Though Migration highlights a real aspect of bird migration, the filmmakers definitely took some, shall we say, liberties. You would be hard-pressed to find real-life ducks as close knit as the movie’s Mallard family. “By the time female Mallards incubate their eggs, males are usually out of the picture,” says Aaron Pearse, research wildlife biologist at USGS. “Even ducklings from the same brood may not necessarily stay together,” he says. (Sorry to those who loved Dax and Gwen’s on-screen sibling dynamic). Beyond that, ducklings that have yet to molt don't have the right feathers to fly, making this family affair even less plausible.

And although Jamaica is certainly a fun vacation destination, the only Mallards known to exist there were likely introduced by humans. According to Brasher, increasingly warm winters across North America means that northern Mallards are less likely to migrate south at all, let alone all the way to the Caribbean. 

Of course, Migration is a children's movie after all, so some embellishment is expected. The mere fact that a major studio produced a children’s comedy about birds is worth celebrating, as it's sure to inspire a new generation of bird-lovers. Though simply wanting an adventure is perhaps the least likely reason for a bird to migrate, it makes for a thrilling story. 

Associate editor Zoe Grueskin contributed supplementary reporting.