Owls against owls in a challenge for survival. Scientists are puzzling out how to address the declining numbers of northern spotted owls (NSO) in their Pacific Northwest forest habitat. A new study explores the reasons why spotted owls are losing a foothold in their habitat, forecasts future habitat conditions and species interactions, and suggests best management practices. Source 5z.
So it isn't the first time that the species were listed as "Endangered" since there was always a few number of them. Despite the increase from that it seems that the environment including the never ending food web seems too dangerous for the owls.