For some odd reason US art doesn't figure too prominently in European school systems.
Ok, I thought you were American. It's not so much the art, he was a naturalist who could draw and paint. And therefore "captured" and catalogued American bird species in their natural habitat. By doing this he offered invaluable knowledge to not just American naturalists and scientists, but European ones as well. As there are many species, like the Golden Eagle, which are found in America and in Europe.