Thanks. I made two emergency ones out of old jeans, one stays on the other doesn't :/You can make them yourself with a bit of sweatshirt or polarfleece fabric and scissors, no sewing:
I have made and used several of these. I don't even bother with the tail hole, only the wing holes. Sometimes it took me 2 or 3 tries to get it right, but then it would stay on for weeks if I wanted.
There are usually some for sale in our BST forum, as well: