Feline Mystery

I have a physicist's distaste for biology ("Yuck! It's all squidgy!"), but sometimes I wish I knew more to give me insight into those biological problems that impinge on my consciousness:

Nimrod, the Mighty Hunter with whom I share my life and my stipend, simply will not eat Whiskers's nice meaty chunks of rabbit or beef: only chicken will suffice. This is a source of tension between us, as Mr. Whiskers prudently sells his meat chunks in packs containing packets of rabbit, beef and chicken. There are no flies on Mr. Whiskers, although there are on the cat dish should I be foolish enough to put out rabbit. Nimrod will have none of it, and she stares at me reproachfully until I feed her chicken chunks instead. This is not the oddity. After gorging herself on chicken, she will track down, torture and kill field mice. This, too, is not the oddity. Having killed the mice, she chews the heads off. What sort of creature turns her nose up at meaty chunks of beef, but eats mice heads? It defies logic and mocks reason. She doesn't even like the mice heads; about once a week they are vomited up under the kitchen table as a lovely present for me. It is very puzzling.

In the meantime, should anyone be interested in a job lot of Whiskers beef, or indeed rabbit, chunks, perhaps they'd get in touch below. Otherwise, eBay beckons...