The Parrot Club I'm part of has tried in the past to do "Birds the park" where essentially for one meeting we were meeting in the park.
I don't think these were the most successful meetings and were eventually discontinued. I know we had talked about potentially bringing them back this year but it was a no go - not enough interest.
Meetings inside were generally better received as people can have their birds out and about in the room. Not everyone has a bird that is used to a harness and not too many where happy with the idea of having their birds in the cage for the entire meeting outside.
Here is a set of pictures from one "Birds in the Park" which happened in 2006
Birds in the Park 2006




