I received -- as a gift -- a small skull mounted on a carved wooden background, typical of Bavaria. I've looked online but am confused about US customs requirements. Can I bring this through? If not, and I declare it, will they just confiscate the item or will I just be fined?
You really shouldn't have a problem. From the CBP site:
For further concerns CBP refers you to APHIS for further information as this is an actual regulatory body responsible for import of animal byproducts:
However if you are concerned about it still you can ship it to yourself and avoid bringing it over the border on your own.
Hopefully you were able to bring your deer skull home safely but if anyone else was wondering...here is a comprehensive list of sports equipment that you can and can't bring on airlines based in America.
(Technically a deer skull would be sports equipment b/c it is a product of hunting.)
Tld;r: While a part of it is based on international regulations, most likely it depends more on the airline and its policies.