or reclaimable, and in which there is a valuable property, as sheep, oxen, swine, and horses, which we in general call cattle; and so Fleta[o] defines it, _pecus vagans, quod nullus petit, sequitur, vel advocat_. For animals upon which the law sets no value, as a dog or cat, and animals _ferae naturae_, as a bear or wolf, cannot be considered as estrays. So swans may be estrays, but not any other fowl[p]; whence they are said to be royal fowl. The reason of which distinction seems to be, that, cattle and swans being of a reclaimed nature, the owner's property in them is not lost merely by their temporary escape; and they also, from their intrinsic value, are a sufficient pledge for the expense of the lord of the franchise in keeping them the year and day. For he that takes an estray is bound, so long as he keeps it, to find it in provisions and keep it from damage[q]; and may not use it by way of labour, but is liable to an action for so doing[r]. Yet he may milk a cow, or the like, for that tends to the preservation, and is for the benefit, of the animal[s]. [Footnote i: Mirr. c. 3. Sec. 19.] [Footnote k: 5 Rep. 108. Bro. _Abr. tit. Estray._ Cro. Eliz. 716.] [Footnote l: Stiernh. _de jur. Gothor._ _l._ 3. _c._ 5.] [Footnote m: Dalt. Sh. 79.] [Footnote n: Finch. L. 177.] [Footnote o: _l._ 1. _c._ 43.] [Footnote p: 7 Rep. 17.] [Footnote q: 1 Roll. Abr. 889.] [Footnote r: Cro. Jac. 147.] [Footnote s: Cro. Jac. 148. Noy. 119.] BESIDES the particular reasons before given why the king should have the several revenues of royal fish, shipwrecks, treasure-trove, waifs, and estrays, there is also one general reason which holds for them all; and that is, because they are _bona vacantia_, or goods in which no one else can claim a property. And therefore by the law of nature they belonged to the first occupant or finder; and so continued under the imperial law. But, in settling the modern constitutions of most of the governments in Europe, it was thought proper (to prevent that strife and contention, which the mere title of occupancy is apt to create and continue, and to provide for the support of public authority in a manner the least burthensome to individuals) that these rights should be annexed to the supreme power by the positive laws of the state. And so it came to pass that, as Bracton expresses it[t], _haec, quae nullius in bonis sunt, et olim fuerunt inventoris de jure naturali, jam efficiuntur principis de jure gentium_. [Footnote t: _l._ 1. _c._ 12.]