Small birds are having a big moment.

Tiny turkeys will increasingly grace Thanksgiving tables next week, thanks to the millennial generation’s ongoing campaign to remake American gastronomy. The holiday depicted by Norman Rockwell—Grandma showing off a cooked bird so plump it weighs down a banquet plate—is still common. But smaller families, growing guilt over wasteful leftovers and a preference for free-range fowl have all played roles in the emergence of petite poultry as a holiday dinner centerpiece.

“People are starting to understand it’s not natural to grow turkeys up to 30 pounds,” said Ariane Daguin, co-founder and owner of D’Artagnan LLC, a wholesale and e-commerce food company in Union, New Jersey. “In general, that means they were penned up with no room to move around, and that’s why they’re fat like that.”

There are signs that wee birds are in greater demand. Inventories of whole hens, which are smaller than males, are down 8.3 percent from a year ago, the latest U.S. Department of Agriculture data show. Whole toms, the males, are up 6.9 percent.

Don’t call them capons. They’re not castrated chickens. Nor are they chicks. They’re not babies. They’re just turkeys that weigh in the neighborhood of six pounds.

Bell & Evans is working with a breeder to make tiny turkeys that consumers will eat all year. Owner Scott Sechler said the new breed, which isn’t yet sold publicly, “fills out nicely,” unlike other undersized birds, which can be bony.

Still, 12- to 14-pound turkeys remain the biggest holiday seller, Sechler said. That may be because some millennials are “still going…