I myself had only heard descriptions of the Nez-Perce bows, so I would not by that picture call them recurved, but at least the portrait of the Spokane cheif painted by paul kane in 1847 features clear recurves in a gull winged bow that would be classified as recurves even today. The cheif is holding a bow of this type in his hand and has another in his quiver that would show more of reflexed tips. I have also read about a Spanish man called Cabeza de Vaca who travelled in the southern plains in the 1530's. He described some bows to be simillar to the turkish bows by profile. This would indicate that some bows had recurves while being gull winged. He also described sinew backed bows and selfbows. Hornbows were also mentioned.