Last month I read a fascinating article regarding the Bearded Vulture, an Old World vulture and one of the rarest raptors of Europe.
This huge bird is the only vertebrate which predominately eats bone; marrow comprising 90% of its diet. While it can ingest bones up to 11 inches long and 1.5 inches wide, if the bone is too big to swallow, this bird will carry it high enough to break when it drops on rocks below. Mammal bones have higher energy content than muscle tissue, because of their high fat content…so a bone diet makes perfect sense. The article went on to state the Bearded Vulture will discard less energy-dense bones and choose only the bones containing the highest fat content both for its consumption and delivery to its young. You can find the entire article here.
I found this interesting when later I also read a piece regarding Great Horned and Snowy Owls which, when food is plentiful, become selective with what they choose to eat. Apparently, owls might raid a large colony of rats and choose to eat only the brains, leaving the rest of the head and body behind. (from: Owls, A Wildlife Handbook – by Kim Long 1998)
I wonder if brains are a lot like bone-marrow and are really fatty and high in energy. I’ve had marrow, and love the rich, buttery texture. I’ve had ‘brains’ too…but I understand they were more likely 'sweetbreads' ... the thymus gland. The etymology of the word "sweetbread" is thought to be of Old English origin. "Sweet" is probably used since thymus are sweet and rich tasting, as opposed to the savory taste of muscle flesh.
At any rate, while rich…I do not remember them being fatty; but then, they weren’t brains.
Perhaps this Red-tailed Hawk
is a gourmand as well…