Actually, the FAA was only grounding the cranes as a byproduct of grounding planes — specifically, the ultralight craft that guide the endangered birds on their migration route. Whooping crane chicks raised in captivity, which many of them are since the birds are so threatened, don't have parents to demonstrate migration to them. So conservationists from Operation Migration have the babies imprint on pilots dressed as birds. Then the chicks follow the ultralights on the 1,200-mile flight.
Evidently the FAA doesn't find this as adorable as I do, because they're now quibbling over whether the pilots are allowed to keep training their flocks of babies. Ultralights aren't allowed to "fly for hire," i.e. commercially. Since the pilots are employees of Operation Migration, they are maybe flying for hire, I guess, even though they take the migration in short hops and are only in the air for an hour a day and by that definition of "for hire," most office workers play professional Minesweeper. But hey, why NOT interpret the rules in such a way that teeny endangered birdies can't get to their wintering grounds?
The agency has relented and agreed to let the cranes finish this year's migration (they decided to halt operations when the birds were 550 miles from their goal). But apparently this is a "one-time exemption" so it's not clear what will happen to next year's crop of Operation Migration chicks. Officials should have to look through this year's flock's dossiers and photos before making a decision, because they are uber-cute.
Bonus! Here's a video of migration practice: