I'm in the early stages of researching a book on the economic history of the Chickasaws, a small but strategically-important southeastern Indian nation that in the 19th century would become one of the Five Civilized Tribes. In the course of re-reading Charles Hudson's description of the 16th-century Chicazas (the principal ancestors of the Chickasaws) in his 1997 book Knights of Spain, Warriors of the Sun (U. of Georgia Press), I came across this account of Chickasaw archers' military prowess: when the Chicazas attacked De Soto's men in the winter of 1541, they succeeded in killing nearly 60 horses, twelve of which they shot through the heart. The horse of hidalgo Juan Diaz was supposedly killed by an arrow that entered its shoulder, went through the entire body, and "protrud[ed] on the opposite side the length of four fingers" (p. 269). Another died after two arrows entered its heart from two different directions.
Hudson bases this chapter on 16th-century accounts of the Soto expedition, chiefly the narrative of the Gentleman of Elvas. I must say I find this account of Chickasaw archers' virtuosity somewhat difficult to believe - their arrows would have had to have been of the same strength as medieval longbowmen's arrows in order to have that degree of penetrating power. It doesn't surprise me, though, that they would consider the Spaniards' animals important targets, since horses gave Europeans a military advantage nearly as important as that provided by their firearms and steel weapons.