Saving a local wildlife habitat.

We are at present trying to persuade our local council not to allow planners to grant planning permission for houses to be built on a small overgrown area near our houses. It supports a wide variety of bird life, insects and small mammals most of which visit our gardens to use the bird feedersand/or pollen rich plants.I am looking for help and advice as to how we can be an effective(but legal) opposition to these plans.We have contacted our local councillor to ask him to speak on our behalf at any planning meetings but wonder if there are any other bodies, such as the Rspb who could help us fight our corner as it were. All sensible suggestions gratefully received.Thank you Kind Regards,.Woodpigeon