The cages in the corners are the hardest to get. You need to get the crab in a position where you can turn and push it in instead of having it follow you. They will walk away from you when you get too close, say one step away, usually sideways but it is possible to make him go diagonally in front of you. If you only have one cage left then at least you can walk around freely without getting caged yourself so just keep trying.
I can get across the bridge into the field, but one of the crabs always steps on the button, collapsing the bridge and leaving some stranded. I've tried to bring one across at a time, but haven't had any success with that, either. Any clues or hints??? Please?!
I didn't have any trouble getting the crabs back across, I found if I walked far enough in front of them they didn't stand on the button. I took them across two at a time. The very last one did stand on the button but it didn't matter by then.
Remember diagonal? That's how to avoid pressing the button. If you after diagonal take one step to the left, the crab will also go diagonal. Bring two at the time