MPs were told that councils demand pages of paperwork for every visit, even though outdoor education centres have already been vetted for health and safety.
Andy Simpson, from the Royal Society for the Protection of Birds, revealed the number of forms that had to be filled before children could try the most "hazardous" activity at its centres - using small nets to look at wildlife in ponds.
The RSPB has now been asked to provide pound;15 million insurance cover for school visits to some of its 34 reserves in the UK where it runs a "living classrooms" scheme. Mr Simpson told MPs: "Short of an organised team of six golden eagles carrying out a child, which is unlikely, we don't know when that would be necessary."
Outdoor education organisers told the House of Commons education select committee that rising costs, bureaucracy, and the busy curriculum were putting many teachers off arranging trips.
Dr Anthony Thomas of the Real World Learning Campaign said: "Quite clearly we are mollycoddling our youngsters. If you over-protect, I think you are doing a disservice to young people. David Bell, the chief inspector of schools, said earlier this month that young people were being deprived of outdoor activities because teachers feared they might be sued.
But a survey by the Field Studies Council suggests that teachers say the principal reasons for not organising trips are the difficulty finding time in the curriculum, followed by costs and problems arranging supply cover.