50 CFR § 26.21
General trespass provision
July 17, 2020
(a) No person shall trespass, including but not limited to entering, occupying, using, or being upon, any national wildlife refuge, except as specifically authorized in this subchapter C or in other applicable Federal regulations.
(b) No unconfined domestic animals, including but not limited to dogs, hogs, cats, horses, sheep and cattle, shall be permitted to enter upon any national wildlife refuge or to roam at large upon such an area, except as specifically authorized under the provisions of §26.34, §27.91 or §29.2 of this subchapter C.