The commissioner may appoint as custodians persons who may have in their possession injured, sick or immature birds or quadrupeds until such time as they can be released, and he may issue permits without fee authorizing possession of legally acquired wild birds or quadrupeds as pets or for the purpose of training dogs. The commissioner may regulate the number and species of birds or animals to be held under such permits and the type and size of pens used in their confinement and their care and feeding. The commissioner, in the interest of protecting other game, domestic birds or quadrupeds or the public health and safety, or for a violation of any regulation under which the permit was granted, may revoke such permit and may confiscate birds or animals possessed by the permittee and may destroy such birds or animals when, in his opinion, such action is advisable. Such permits shall expire December thirty-first of each year and may be renewed each year. The commissioner may require such annual reports from such permittees as he deems advisable. Any person who possesses any such bird or quadruped for any of such purposes unless so authorized by the commissioner shall be fined not more than one hundred dollars.