Elly, is the term 'witches broom' a new one to you? I'm sure you've seen them, but didn't know what they were. They don't qualify for barred owl housing. (See image in the attached link.) Spinster, I heard barred owls many times last year. One would even land on the peaks of our roof and call away. THAT'S something that will make you jump right out of bed! Anyway, a witches' broom is a dense cluster of branches, seeming to rise from a central point. It is a mutation found on a wide number of woody plant species, and is caused by a genetic mutation, or by a mutative response different kinds of insects. They can be huge or very small. Some witches' brooms result in some interesting new plant cultivars. The ones found in conifers are often hunted and collected. Here is a link that might be useful:

Yes, Bob, you have to be a licensed falconer to own a captive bird of prey? The training is time intensive so usually only those individuals really dedicated to owning, caring for, and hunting with a raptor become falconers. BN

Since barred owls use nest boxes, I imagine one could be put up on your tree with proper reinforcement to keep it in place, after nesting season. I know the boxes are larger than the E. Screech Owl box we put up in our tree and I agree if that nest is up high it's best to use a skilled tree person. Not far from me, there was a barred owl nesting in a snag and weather deteriorated it to the point the owls found another tree nearby. The original nest was along a walkway in a park. I haven't found the new nest, but I have seen the owls at dusk and hear them.

I don't know how deep the nest actually is because I can't get up into that tree. From what I've been able to see, however, it appears that they are really exposed to the weather more than I ever expected them to like for nesting. There was once a very large limb that broke from this tree and eventually it developed into this large cavity. You can still see some of the limb at the top of the nest site. That area of the tree has really deteriorated over the last few years and I worry that it will soon be too open for the owls to continue to nest there. The tree is slowly dying and is losing limbs every year. Many sections of the tree have holes in it made by Pileated Woodpeckers. Squirrels and birds fly into one hole and out another hole in another section of the tree. Definitely hollow spaces in there. I've been contemplating making a nest box and mounting up that tree in that nest area for next year. I'm just not sure what to do. I've watched them nest there every year since 2003 and I would truly miss them. I want to offer a nest box but at the same time I don't want to spook them away from the site they have used for so long. Here is an image from 2003 when the young were leaving the nest and the tree is full of foliage.