No, Connie, hawks are not out after dark, not hunting at least. They cover the day shift, and Great Horned Owls the night shift. They are the bigger threat!
I can't tell for sure by that pic, but that might even be a Ferruginous Hawk (beautiful bird!!). You get them in ND breeding in spring & summer. Or it could be a light morph redtail hawk. Either way, keep your babies very close!