Spell Ingredients, hard to find bio types Options

I've been looking through some spells that require certain animal parts that are sort of unusual, and I was wondering for anyone who uses those kind of ingredients where you find them. Huge range from things like feathers and teeth to 'eye of night owl', snake skin, bones, etc. I know there are some who go to the zoo and try and get discarded castoffs like teeth and fur, but that's kind of limited. There are also biological supply companies that cater to dissection classes and such, but that also has limits (not to mention... dead and preserved with lots of funky chemicals). So for anyone who uses those kind of ingredients in magic, I'd be interested to know where or how you find them.

Animal bones and fur can be found on the roads, just off the side of a road, and in the woods--you just need to be able to identify animal/bird bones unless some carcass is still attached.

Look to the sky for circling hawks and head in the direction of cawing crows who flock and caw above death. Also hawks kill crows so a group of cawing crows may mean one of their own ihas been attacked--if you need some large black feathers, etc. Also, crows will sit along roads that are known for heavy roadkill.

Snake skins can be found where snakes sun themselves, usually sunny/sandy areas or around rocks.

Butcher shops and hunting shops have access to bones, skin, internal organs, horns, etc.