Cost constraints prevent us from waterproofing our cameras. They are, of course, protected inside a birdhouse. But, if used outdoors, all it takes is placing them under the eve of a roof, or roof of a platform feeder, or put a small 6" square piece of plywood or plastic over the top to provide adequate protection.
Here are the solutions I like best:
1) Cheap and easy. Take one of those small, disposable plastic water bottles, and cut off the top and bottom so you have a tube 3-4 inches long. Then cut it lengthwise. Now simply pull the edges apart and slip it over the camera. For a more robust shelter, go down to your local hardware store's plumbing section and buy a 2.25 (original Hawk Eye) or 2.5" (Hawk Eye HD), 45-degree PVC elbow. The camears will slip right up inside and can be held in place with a dab of hot glue, or velcro.
Here's what I'm talking about: