Most of the owl pellets I've found are in the 1.5 to 2 inch range. The pellet above is longer than 4 inches. It has got to be the Mother Of All Owl Pellets.
Owls are not able to chew their prey and unlike most other birds they do not have a crop for storing food. Therefore, what an owl kills is passed directly to their digestive system. The first chamber of the bird's stomach is called the proventriculus. The acids and enzymes here begin the process of digestion. From there the prey passes to the gizzard or ventriculus. This functions as a way point for the holding of indigestible matter - namely fur, feathers, bones, etc. Everything else passes through the small and large intestine to the cloaca and is ultimately expelled through the vent. With the exception of the ostrich birds do not have a bladder so whatever is excreted from the vent is largely acid - the white substance that makes up bird poop.
Back to the ventriculus. All of the undigested stuff now blocks the bird's digestive system so the bird cannot feed again until it is expelled. Muscular contractions in the gizzard compress the contents into a pellet.and send back to the proventriculus from which it is regurgitated. This may have come from a different bird of prey but either way I would have given anything to see the raptor that hacked this up. Big pellet - big bird!
When I have some extra time I'm going to dissect this curiosity and see if I can learn more about the raptor's dietary choices. I'll report back with my findings.
I hope this post got you thinking about what you're having for lunch...
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