In my experience there is only one effective way to catch squirrels, unless you have a gun. The spring trap tunnel works well and dispatches the quarry on most occasions which is what you want as it is illegal to release them back into the wild as they are classed as vermin. you should be aware that the rspca have prosecuted people for killing squirrels in what they regard as an inhumane way. There is a book called trap making step by step the author is john bryan ISBN 978-0-9558535-0-0 this will give you all the info you need. Good hunting and remember corn fed squirrel taste delicious.