Since “The Twelve Days of Christmas” originated in England, it should be a safe assumption that the creatures named in it are those found in England. So, I have decided to correlate the song to iNat.
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A partridge in a pear tree. The only partridge originally native in England is the Gray Partridge. The pear tree is probably the Common Pear, since that is the one commonly cultivated for fruit.
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Two turtledoves. The European turtledove occurs in several subspecies, of which the one found in most of Europe and part of Britain is the Northern Turtledove.
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Three French hens. Whatever breed a “French” hen was, it would have been the same species as every other breed of Domestic Chicken. One source suggests that the “French” reference might be a word-association pun, genus Gallus with the adjective Gallic.
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Four calling birds. Many passeriform birds have distinct songs, often erroneously called “bird calls” by laypersons; but in researching this, it is hard to escape the seeming consensus of sources saying that it was originally “colly birds,” meaning coal-black birds, and thus must mean the Western European Blackbird.
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Five golden rings. I cannot correlate that with iNaturalist, since gold is a mineral and hence does not even qualify as “State of Matter Life.”
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Six geese a-laying. This would have likely been the Domestic Greylag Goose, although not necessarily, because the Domestic Swan Goose had reached Europe by the 1730s, and thus made possible the Domestic Greylag X Swan Goose.
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Seven swans a-swimming. Probably the Mute Swan, since that is the year-round resident of the latitudes of Britain, and has also been domesticated. However, since Christmas is in winter, the Whooper Swan and Bewick’s Swan migrate to those latitudes.
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Eight maids a-milking. They were probably milking Domestic Cattle, although there is a history of milking Domestic Goats as well.
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Nine ladies dancing,
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ten lords a-leaping,
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eleven pipers piping,
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twelve drummers drumming. Since all of these are observations of Human, they will be relegated to casual and not further elaborated.