Smithsonian contributions to knowledge, Vol. 28 page 387 notes the following. Bubo virginianus saturatus or Coastal Great Horned Owl used to be referred to as the Dusky Horned Owl. It also notes it's the darkest of Bubo subspecies, also that Robert Kennicott found a nest with two eggs near Fort Yukon, Alaska, April 16, 1862. Seems like they took the eggs and killed the mother and marked her item No. 27075, of the U.S. National Museum collection. The nest was found atop a spruce tree in a grove of spruce. It was shallow and lined with a few feathers.