One can understand why the folks at Blue Sky Studios, the animation house that made the “Ice Age” movies, would want to situate their new film in a warmer climate. Being stuck in a glacier for months, even in cartoon form, can’t be all that much fun. But though “Rio” moves the action to modern-day Brazil, it proves less emotionally warm than the pictures set in the frigid prehistoric period. The two couples at the center of the movie—one avian and the other human—aren’t terribly endearing. And although some of the secondary characters surrounding them are amusing, and the music is generally pleasing (and sometimes clever), the result falls into the mid-range of the animated pictures released with tiresome regularity nowadays. In other words, it’s not “Mars Needs Moms,” but neither is it “Rango.”

The “star” is a tropical parrot called Blu (voiced by Jesse Eisenberg, rather stiffly). He was taken from the forest by smugglers even before he could learn to fly, and improbably wound up in Moose Lake, Minnesota—whose snowbound visuals provide a link with “Ice Age”—where he becomes the pampered pet of mousy bookshop owner Linda (Leslie Mann). Their life as a couple is interrupted by the arrival of Tulio (Rodrigo Santoro), who tells Linda that Blu’s the last male survivor of an endangered species and wants to take him to Brazil to mate with the last female, Jewel (Anne Hathaway).

It’s a mismatch between wimpy, nervous Blu and aggressive, bossy Jewel, of course, but that becomes secondary when they’re snatched by another team of smugglers headed by Marcel (Carlos Ponce), whose nasty henchman is a wild-eyed cockatoo called Nigel (Jermaine Clement). They escape, but chained together, and so their flight is flightless as Blu can’t soar. Happily they encounter a few friends to help them along—a toucan named Rafael (George Lopez), a canary-cardinal slapstick team called Nico and Pedro (Jamie Fox and, and drooling bulldog Luiz (Tracy Morgan).

After the opening reel in Minnesota and the initial scenes in Brazil, “Rio” is a chase as perpetual as any Loony Tunes short—but it goes on for more than an hour and a half. It tries to make up for that with nice backgrounds and bright colors (all in popular 3D), some sprightly musical numbers (the wittiest being Nigel’s unapologetic “Pretty Bird”), and an array of typically goofy supporting players (not just the ones mentioned above, but Marcel’s goofy underlings and an army of thieving monkeys Nigel enlists in his pursuit of the parrots, as well as—for sympathy’s sake, a street kid voiced by Jake T. Austin). And of course the makers keep the action moving forward at a furious pace.

But all the pizzazz really can’t hide the fact that at the center the movie’s lacking. Blue and Jewel aren’t a terribly interesting pair; one supposes they’re supposed to be an animated avian version of the sort of bickering couple familiar from screwball comedy, but they don’t make the grade. The voice work is part of the problem—Eisenberg is bland and Hathaway comes on too strong—but the look of the characters isn’t inspired, either. The human couple is no more ingratiating, with Mann and Santoro (as well as their bumbling characters) striking no sparks.

The result is another middle-grade piece of computer animation from Blue Sky. “Rio” is neither great nor terrible—just mediocre. Happily it’s preceded by another high-octane short featuring scrat, the best character from the “Ice Age” flicks. A pity the feature that follows doesn’t measure up to it.