After a passenger attempted to board a flight from Newark Liberty International Airport with what she called her emotional support peacock, United Airlines has been forced to tighten its rules on creatures of the emotional support variety.

Read: An Emotional Support Peacock? United Airlines Won’t Let It Fly

Mirroring an announcement made by Delta Airlines in late January, United is implementing a new policy that will be rolled out starting March 1. Passengers flying on United will be required to provide documentation from their vet that the animal is safe to fly, showing that the animal is up-to-date on all of its vaccinations and is not expected to threaten the health and safety of others. This entails confirming that the animal is trained to behave in a public setting and that the owner will take responsibility for the animal’s behavior. The 48-hour advance notification policy will also remain in place.

Read: Delta’s New Emotional Support Animal Policy Will Make It Harder to Travel With Your Pet

Service animals, however, will not require advance notice or special notification. And some other animals are banned from the cabin across-the-board, including insects, rodents, snakes, spiders, reptiles, hedgehogs, ferrets, and non-household birds. United reportedly plans to continue to review this list.

United explained that its new policy was necessary, as existing Department of Transportation rules are not sufficient to “ensure a safe and pleasant travel experience” for its passengers. According to The Wall Street Journal, the department plans to launch a public consultation this year to “refine its definition of what constitutes a service animal.”