It may seem odd, but genealogists can sometimes learn important information because of the animals their ancestors owned. In my own hometown in Maine, several pages of town records around 1890 were devoted to recording the names and owners of licensed dogs in the town. Along with the joy experienced upon learning that one's great-great-grandfather named his dog "Rufus" comes the more valuable insight that he did indeed live in the town in the year noted.
Sometimes establishing residence is of vital importance. In Plymouth, cows and goats were distributed among the settlers in 1627. Records of the division of cattle offer a sort of census of the colony, giving the names of every man, woman, and child. As records for some families are sketchy in the early years of the colony, genealogists can point to this record as proof that their ancestors arrived prior to 1627—or, as with my own Dunham forebears, as evidence that they had not yet arrived.
Also useful to genealogists are records of crop marks, or ear marks. These were the slits and notches cut into animals' ears to show ownership.1 The first pages of Plymouth town records list ear marks, in compliance with a law of the Colony Court, passed Nov. 15, 1636, that "every mans marke of his Cattle be brought to the towne book where he lives and that no man give the same but shall alter any other brought by him and put his owne upon them."2
John Wood a hollow cut out on the top of right yeare.A son would often inherit or adapt his father's mark—a sensible policy if inheriting his father's livestock. In towns where crop marks were diligently recorded, a genealogist may find in them proof of parentage, in addition to proof of residence in the town. Two men sharing the same name may be distinguished by their different crop marks. And record of a young man's first crop marks might be taken as evidence that he had that year "come of age."
Giles Rickett the top of the left yeare cutt of and a slit upon the same yeare.
Lieftennant Southworth the marke of his Cattle is a cropp on the left eare.
John Dunhame senior the marke of his Cattle is a croch on the left eare.3
1Occasionally a mark somewhere else on the animal, for example on a hoof, was used.
2Records of the Town of Plymouth (Plymouth, Mass., 1889), 1:1.