Well, this was a first for me.
Great horned owls don’t build their own nests. Instead, they usually take over another raptor’s pre-existing nest or choose a cavity in a tree. This owl opted to take over a much smaller bird’s nest, that of a magpie.
As you can see, while the nest is tall, it isn’t very far across and so the owl doesn’t have much room in there. Once it has little ones that start growing, it will be pushed out.
For the time being though it is extraordinarily well hidden in there. I would have never known it was there if a friend hadn’t tipped me off to it.