The USDA does not regulate the private ownership of exotic animals; such regulation falls to states and local municipalities in the United States.

Most entities selling, breeding, brokering or displaying ANY animals do need to hold a license, but there are a few exemptions which do include retail pet stores.

License Exemptions:

Retail Pet Stores: Anyone whose entire business consists of selling domestic animals to pet owners is exempt. However, if as part of your business you exhibit animals, you may have to be licensed as an exhibitor. For example, you need an exhibitor's license if you take animals outside the store for teaching or promotion or if you set up a petting display. You must be licensed as a dealer if you sell wild or exotic animals, or if you sell regulated animals to other retailers, research institutions, exhibitors,or other animal dealers. You need to be licensed as an exhibitor if you display a monkey or other wild animal inside the store. Exemptions for retail pet stores are on an all-or-nothing basis. If you qualify for exemption, none of your business is regulated or inspected. If you do not qualify, you are a full-fledged dealer, and all your regulated animals are inspected.

Retail Chain Stores: Centrally managed stores that sell pets entirely at retail are exempt. Like independent retailers, chains are treated as business entities on an all-or-nothing basis. If all outlets qualify as retail pet stores, the entire chain is free from regulation. Conversely, if any outlet does not qualify as a retail pet store, the company must be licensed as a dealer, and all regulated animals at all outlets are inspected.

Caveat to exemption:

If you sell any wild or exotic animals, you are not eligible to claim exemption as a retail pet store You become a full-fledged dealer, and you must comply with standards of care for all regulated animals-not just wild or exotic animals.

Exotic Animal Dealers: Anyone importing, buying, selling, or trading animals foreign to the United States (wild or domesticated) must be licensed. You also must be licensed if you sell domestically bred exotic animals. Annual license fees are based on the amount received from the sale of regulated animals less the amount paid for these animals.

Wild Animal Dealers: A business or individual selling wild animals must be licensed. "Wild animals" means any animal that is now or historically has been found in the wild, or in the wild state, within the boundaries of the United States, its territories, or possessions. This term includes, but is not limited to, animals such as deer, skunk, raccoon, mink, armadillo, coyote, squirrel, fox, and wolf.

What this means to you:

If you comes across a pet store, kiosk, flea market space selling sugar gliders, they must absolutely have a USDA dealers license and should be able to present that to you. Many small pet stores are actually breaking this law.

Read More:

USDA Licensing Requirements
USDA does not regulate the private ownership of exotic animals