The ospreys are thought to be the only nesting pair in Wales
A disagreement about the running of an osprey nesting site in Gwynedd has resulted in volunteers flying the nest.
The Glaslyn Osprey Community Society (GOCS) claims the RSPB is using the site primarily to recruit members.
They also claim a promise to hand the site at Pont Croesor to the local community to run has been broken.
The RSPB said no promises had been broken and membership was encouraged, but the main reason for the site was to promote and protect the ospreys.
The project was set up in 2004 when the ospreys - the only breeding pair in Wales - first arrived.
It was initially paid for as part of an European Objective One-funded project called Aren't Birds Brilliant.
The birds have attracted thousands of visitors to the area since 2004, and have come back to the nest site again this year, returning from Africa about three weeks ago.
Gwen Williams, who has both worked and volunteered on the project, said the RSPB was changing the site and using staff to sell membership, rather than tell visitors about the birds.
"In the past there was someone on the site who was responsible for taking the details of anyone who wanted to join the RSPB, but now all the staff have to sell membership," she said.
Ms Williams said she had decided not to volunteer at the visitor centre as a result, although she will still volunteer to watch the nest site.
"I won't go anywhere near Pont Croesor, but I will still work to protect the nest to make sure no-one gets to the eggs - protecting the birds is the most important thing," she said.
John Parry Williams said he had put in between 900 and 1,000 hours of volunteering at both the nest and visitor centres.
"I've been involved since the start and my understanding was that the site would be handed back to the local community," he said.
"They also want to turn it into a membership-collecting factory and I feel very strongly about the whole situation," he added.
Mr Williams said he was cutting all contact with the project as a result.
RSPB Cymru director Dr Tim Stowe said: "The (Objective 1) funding contained no proposal by the RSPB, and no stipulation from the EU, to stop running the operation at some future date and hand it over to a third party."
Dr Stowe added that the RSPB had always worked with the community on the project, setting up a local forum, with an independent chair, and using large numbers of local and visiting volunteers.
"It has been a very successful partnership," he said.
"The purpose of showing people the only nesting pair of the iconic fish-catching osprey in Wales is to foster their enjoyment of Welsh wildlife and to support its safeguarding and conservation," he added.
"If visitors wish to support our work by joining, we think that's fantastic.
"As a charity, particularly in the current economic climate, we need as much support (volunteers and memberships) as we can get to help us show these birds to the people of north Wales," he said.