The large metal birds mysteriously began roosting in the park as part of an apparent attempt to meld the two worlds together, The Portland Oregonian said.
While park officials tolerated previous instances of individuals decorating park trees for Christmas, they said the new artistic birds are a step too far.
"This is supposed to be a natural habitat and recreation area, not an art gallery," park official Gail Snyder said.
Due to their impressive size, one metal parrot measures six feet tall and locations, park officials admit the art may remain in place for quite some time.
Until then, one street artist told the newspaper that perhaps park visitors could look at the artwork as a unique reminder by the unknown artist of nature's beauty.
"They could be reminding people to look up in the trees a little bit and remember the importance of wildlife," Scott Wayne Indiana said.