The Great Owl Mystery

I was sitting at my desk working when I heard something outside my window. The sun had already set but it wasn't late. Only about 7 or so. The noises kept coming. Owls I decided, but also a coo of another bird, I wasn't sure what.

The next day I remembered my nephew and niece had seen an owl in the pine tree outside my window a couple of months ago.

I decided to investigate. I went and poked around the pine tree and saw something suspiciously white against the yellow pine needles.

It was quickly identified as an ulna (lower arm bone or... wing in this case) of a bird. Next I went underneath the tree. More evidence:

Dark grey, relatively small feathers were scattered everywhere, but there was no evidence of owl pellets. I was disappointed. But did not give up. 

I went and asked my resident ornithologist, she viewed the feathers and suggested some local birds such as Pine siskins, quails, and starlings. 

We compared the new ulna to my comparative skeleton collection (the Flicker from Bird Morality).

The Flicker ulna is 2 inches long and has distinctive bumps running its length.

The new ulna is 1.75 inches long and has no bumps.

The victim was not a flicker.

Because the ulna is part of the wing we decided that it's length would most likely be a fitting ratio to wingspan (instead of length of bird). Flickers, according to wikipedia, have a wingspan of 17-21 inches. 

Now it was time for some math:

2 in = Flicker's Ulna

19 in = Average Flicker's wingspan

1.75 in = Victim's Ulna

x = Victim's approximate wingspan

Flicker (2/19) Victim (1.75/x) 

 x = 16.625 in

Pine Siskins only have a wingspan of about 7 to 8 inches, and quails (besides being too colorful) have a wingspan of 12.6-14.6 inches). Too small.

But starlings had a wingspan of about 12-17 inches. Perfect.

We think the owl had a starling for dinner.

Assumptions: The bone and the feathers were from the same bird.

Ratio between ulna and wingspan is similar between species.