Twitter was a bit incredulous at the idea of an emotional support peacock.
The woman said she bought an extra ticket for the peacock but it was not allowed on the United Airlines plane.
"We explained this to the customers on three separate occasions before they arrived at the airport", airline officials said.
A spokesperson for the airline said: "This animal did not meet guidelines for a number of reasons, including its weight and size".
United Airlines added in a statement on emotional support animals that the airline was "dedicated to providing convenient and comfortable service to all of our customers".
Only one kind of bird went in the air at Newark Airport this week, after an airline did not allow a passenger to bring her "support" peacock on a flight with her.
While the woman offered to pay for the peacock's ticket, the blog said, United would not let the animal onto the flight.
Delta Air Lines recently introduced regulations to prevent passengers from bringing untrained animals onto flights.
United announced that they are considering a similar policy, telling Fox News that they are reevaluating their existing policy on emotional support animals.
Effective March 1, Delta will require passengers traveling with service or support animals to show proof of good health and up-to-date immunizations with 48 hours notice, according to a statement.
The United Airlines incident comes after Delta released a statement on January 19 announcing new requirements when it comes to emotional support animals. The woman was eventually asked to leave the plane, pig in tow. Also in 2017, Delta employees reported increased acts of aggression, including barking, growling, lunging and biting, from service and support animals - behavior not typically seen in properly trained animals. Other "unusual animals" (with the exception of snakes, reptiles, ferrets, rodents and spiders, which are not permitted due to safety and/or public health concerns) may be accepted as an emotional support animal on a case-by-case basis.