It may be recalled that "Res Nullius" are physical things which "have not or have never had" an owner. This includes wild animals, fishes and wild fowl in which property may be acquired by "natural law." While the individual animal remains wild, it is "res communes," or a "thing common to all" (public domain.)
The opinion in Geer v. Connecticut, 161 U.S. 519 (1896), provides an good summary of:
The Roman concept of "res communes" or "things common to all," as applies to "ferae naturae" or wild animals in nature and the qualified right to use them;
The transitory ownership in wild animals while resident upon privately owned land called "ferae naturae-propter privilegium".
The exclusive private "territorial" right to pursue acquisition and possession (hunting grounds or fishery) as an incidence of land ownership or "right of soil" (ratione soli.;) and
The individual acquisition of property or dominion in an animal ferae naturae through occupancy and possession or "take";
USUFRUCTIORY INTEREST IN FERAE NATURAE - WILD ANIMALS
[Geer] "Referring especially to the common ownership of game, he [Blackstone] says:
'But, after all, there are some few things which, notwithstanding the general introduction and continuance of property, must still unavoidably remain in common, being such wherein nothing but an usufructuary property is capable of being had; and therefore they still belong to the first occupant during the time he holds possession of them, and no longer. Such (among others) are the elements of light, air, and water, which a man may occupy by means of his windows, his gardens, his mills, and other conveniences. Such, also, are the generality of those animals which are said to be ferae naturae or of a wild and untamable disposition, which any man may seize upon or keep for his own use or pleasure.' 2 Bl. Comm. 14.
FERAE NATURAE-PROPTER PRIVILEGIUM
[It should be noted that it was common for kings and lords to fence areas know as "chases" to contain wild deer for availability of the hunt. As such, they were temporarily controlled and "possessed," but still wild, falling short of acts necessary to constitute "take" or appropriation into private ownership. They were essentially "used," but not consumed, similar to the use of flowing water to power a mill.]
[Geer] 'A man may lastly have a qualified property in animals ferae naturae-propter privilegium; that is, he may have the privilege of hunting, taking, and killing them in exclusion of other persons. Here he has a transient property in these animals usually called 'game' so long as they continue within his liberty, and he may restrain any stranger from taking them therein; but, the instant they depart into another liberty, this qualified property ceases. ... A man can have no absolute permanent property in these, as he may in the earth and land; since these are of a vague and fugitive nature, and therefore can only admit of a precarious and qualified ownership, which lasts so long as they are in actual use and occupation, but no longer.' 2 Bl. Comm. 394. (Emphasis mine.)
[Primary Reference: John Crook, Law and Life of Rome, Corne;; University Press, c1967, page 147.)
..."There being no game laws, game and fish were the property of those who caught them; though in the case of creatures such as bees, pigeons or deer, so long as they had their hives or cotes or natural haunts on a man's land they were his, but if they moved permanently away they were open to first taking..."
EXCLUSIVE HUNTING AND FISHING RIGHTS
(As an "estate" in the land, "right of soil" or ratione soli)
[Geer] "No restriction, it would hence seem, was placed by the Roman law upon the power of the individual to reduce game, of which he was the owner in common with other citizens, to possession, although the Institutes of Justinian recognized the right of an owner of land to forbid another from killing game on his property, as, indeed, this right was impliedly admitted by the Digest in the passage just cited. Inst. Bk. 2, tit. 1, 12.
"This inhibition was, however, rather a recognition of the right of ownership in land than an exercise by the state of its undoubted authority to control the taking and use of that which belonged to no one in particular, but was common to all...."
Similarly, in "private" or nonnavigable rivers, the owner had an exclusive right of "piscary" or fishery (fishing):
Lord Mansfield in 4 Burr. 2163 stated, the rule of law is uniform. In rivers not navigable, the proprietors of the land have the right of fishing on their respective sides, and it generally extends ad filum medium aquoe....
DOMINION OR PROPERTY IN FERAE NATURAE - A WILD ANIMAL
The traditional body of Western law recognizes that personal property in an individual wild animal or fish, ("ferae naturae,") may only be appropriated, acquired or "taken" through occupancy or possession; depriving the animal of its natural liberty and rendering it subject to the "control" of an individual. Originally, Roman Law held that property in an animal ferae naturae could be acquired by an individual only through bodily touch, ("manucaption,") with the intention of converting it to private use.