Tourists looking to take their emotional support peacock on their next cruise adventure may be out of luck.

Royal Caribbean International, the world’s second-largest cruise line by number of passengers, will no longer allow travelers to bring their emotional support animals with them aboard its ships, effective immediately, a cruise industry blog first reported Tuesday. If passengers made reservations to sail with emotional support animals before July 30, they will still be allowed on board, but subsequent reservations won’t accommodate them.

“We are updating the policy to differentiate emotional support animals from service animals that are trained and certified to perform a function for a person with a disability,” a spokeswoman for Royal Caribbean said in an email to MarketWatch. “It is important to us that all our guests enjoy their vacation, which is why we put into practice this new policy. Royal Caribbean’s policy remains the same for service animals traveling with guests that have a physical or non-physical disability.”

The company did not say whether the policy would apply to other cruise lines owned by parent company Royal Caribbean Cruises, such as Celebrity Cruises.

Royal Caribbean’s ban appears to be one of the first cruise line policies to actively prohibit emotional support animals specifically, said Chris Gray Faust, managing editor of travel website Cruise Critic.

Norwegian Cruise Line does not accept emotional support animals onboard its ships, and neither does Carnival but they do allow service animals. “Norwegian Cruise Line accepts service animals that are trained to perform a specific task,” a Norwegian spokesperson said. On Carnival ships, trained and certified service animals as defined by the US Department of Justice can accompany passengers.

“Cruise lines have quite strict animal guidelines, only allowing service and support animals onboard most lines,” Faust said. The one exception: Cunard Line, a subsidiary of Carnival, has kennels onboard for pet owners to use to house their pets during their trip. Cunard’s website even features photos of a porter walking a bulldog on the ship’s deck.

Emotional support animals have become a hot-button issue, particularly in the travel industry. While state and local jurisdictions may expand further on what can be considered a “service animal,” under federal law service animals are dogs trained individually to do certain work or perform tasks for someone who has a disability. These tasks can include everything from guiding someone who is blind to assisting people with psychiatric disabilities so that they don’t engage in impulsive or harmful behaviors.

Emotional support animals meanwhile are typically not trained by professionals. Additionally, emotional support animals are often considered to be pets, whereas service dogs are working animals and not companions in the same sense. People have claimed creatures ranging from lizards to hamsters to peacocks as support animals.

“It’s a topic that is quite contentious among travelers, due to logistical issues and the lines’ otherwise tight guidelines regarding animals onboard,” Faust said. “With policies continuing to change throughout the travel industry — whether by air, land or sea — it’s more important than ever to familiarize yourself with the guidelines of your travel company of choice to ensure you’re booking with a company that can best meet your needs.”

The Air Carrier Access Act has a provision that requires airlines to allow emotional support animals on planes, as long as the animal isn’t a danger or interference to others and their owner has proper documentation.

A number of airlines, including Delta, American and Alaska have tightened their rules surrounding these animals, which have been known to bite passengers and relieve themselves on planes. Despite the crackdown on four-legged friends, airlines are seeing more emotional support animals on their flights.

Along with the uptick in emotional support animals onboard planes has come an increase in the number of incidents involving them. A young girl was injured on a Southwest Airlines flight in February after an altercation with an emotional support dog.