Dear Mr. Muhlberg,
So sorry that it’s taken me so long to get back to you regarding the bird you asked me to help identify. As it turned out, it was quite a challenge, with the evidence you provided – the feathers, eggshell fragments, photos of the nest and the hole in the attic vent – but as it turns out I must thank you, actually. This turned out to be the most fun I’ve had as an ornithologist in quite some time! So much of my work in the field and the lab can involve long stretches of tedious waiting and watching for the smallest of details.
So, in order to prevent forcing you into waiting in anticipation, I’ll cut to the chase and report that the birds that last called the nest home were owls; more precisely Barred Owls, which are fairly common here in western Washington state, particularly in rural areas.
Now, just in case you are interested, and it sure seemed to me when we met that you are, here is some more detail on how some colleagues and I came to this conclusion.
Above, I wrote, “…birds that last called the nest home…” This is significant, because owls do not build nests. They either nest in hollows in trees that require no construction of a structure, or they claim a nest built and then abandoned by birds of another species. From the size and manner of construction of this nest, and taking into account the size of the hole in the wall, the only possible suspects for the original occupants are large crows, more likely ravens, or red tail hawks, but I must add quickly that these birds are just as unlikely as the owls who more recently moved in. It’s nearly unheard of for any of these birds to either build a nest or utilize an existing nest inside a human dwelling.
The only possible explanation is that the way the house is situated on the property, with the gable end of the roof nearest the woods effectively out of sight of human comings and goings, gave the birds a sense of safety, and that, along with the roof providing a level of shelter not to be found in the adjacent forest, proved enticing enough.
All that said, I’ve no idea how the hole got there. The only possibility I could think of is that a woodpecker, a large one, like the Northern Flicker, created the hole with what’s called drumming behavior, either in an effort to gain entry in order to build a nest, but more likely to attract a mate.
You may be wondering about the Barn Owl, which, incidentally, is what most people think is being referred to when someone says “Barred Owl”, because they’ve never heard of the latter, and it’s phonetically easy to mishear one for the other. Thing is, Barn Owls, though known to nest in abandoned barns and houses, are exceedingly rare in our region, and besides, our final identification ultimately relied on something much more reliable than habitat data: the ever-reliable DNA. We fortunately found plenty of organic matter in the feather quills and follicles and from the inside of the eggshell pieces to positively identify the Barred Owl via an extensive genome repository maintained by the North American Ornithological Society.
And last, as to your other request, for some kind of speculation concerning the impact on the most recent residents of the nest should you quite understandably repair the hole through which the owls entered and exited, I feel confident that I can save you from any guilt. Given the proximity to the sizeable adjacent forest, this family of owls will easily find new lodgings, and the truth is their efforts to find a new nesting site began as soon as you began the remodel construction. They won’t want to be anywhere near that!
Once you are done with construction, however, if you are fond of owls, keep a lookout for them in the trees, and over time I’m sure you’ll enjoy a fair number of sightings. They are really beautiful birds, quietly powerful, and their call rhythmically sounds like, “Who cooks for you? Who cooks for you?” (Hoo, hoo, hoo-hoo. Hoo, hoo, hoo-hoo.)
Enjoy, and once again thanks so much for the unexpected and welcome distraction!
Fictional Professor of Ornithology
Western Washington University