Can't say I wouldn't have done the same thing if I had been in their position. I recall reading how the Plains Indians used to slaughter huge numbers of buffalo, just for the hell of it. But this kind of thing scandalizes the PC crowd, who just must have their own peculiar vision of the Indian. For my part, I'd rather know the truth.
There was a book out years ago by a guy who went to Africa in the 1960's -70's to learn about the "old" ways of the different tribes there. He ended up writing about how they dumped DDT into the creeks to get fish, how they wanted him to use his M-16 to kill a whole herd of elephants and how they slaughted herds of antelope with wire fencing just to get the skins for sale to safari hunters. Guy came home quite dejected, changed his outlook in life.