Idaho Code § 36-508: antlers — horns — license.

A nonresident collecting, possessing, or transporting antlers or horns shed from deer, elk, moose, or pronghorn in this state shall be required to first procure a license entitling the nonresident to hunt big game as provided in chapter 4, title 36, Idaho Code. No license shall be required for a nonresident under twelve (12) years of age who is accompanied by a nonresident who is licensed in compliance with the provisions of this section or by a resident.