Are Shell Casings Biodegradable?

Today was a sunny but cold fall day. I thought I’d try to get a bit of exercise in my day and I went for a walk in the Presqu’Ile Provincial Park. After all, it’s in my backyard and I should enjoy its peaceful beauty as much as possible. The water level is so low right now and I was also curious to see if I could cross by foot on the two islands across the bay. The park was not very busy because the season is not the greatest: it’s cold and all the fall foliage is already on the ground so Nature is not at its best.
I also chose to go today because it’s hunting season and that section of the park is closed off on Saturdays to allow the hunter free roaming where the waterfowl are most present. I’m not really sure why there is hunting permitted in a provincial park; isn’t their mandate to protect and promote the nature? Anyway, I don’t really understand it but I guess if there’s a need for it….. But shouldn’t the waterfowl hunters be respectful of the environment? It was saddening to see plastic shell casings everywhere, not only near the dozens of hide-outs constructed for the hunters but everywhere on the shores. Very sad. I often find shell casings on my beach, all the way across the bay, and wondered where they came from. Now I know. Sometimes it’s better to be ignorant.