Re: Phorusrhacids killing large mammals in National Geographic Channel

[Graydon <oak@uniserve.com>]

On Mon, Aug 10, 2009 at 11:33:33AM -0500, Raptorial Talon scripsit:
[snip]
> > giving up a prey. Anyway, why can't a cat of the size of a domestic
> > one kill an adult rabbit and an ermine can, even when the cat has
> > stronger jaw muscles and canines, related to the absolutely larger
> > head, and even when the cat also uses the same bite at the nape? I
> > think they are bold.
> 
> As far as I'm aware, housecats *can* kill adult rabbits, but usually
> prefer easier prey.

Absolutely, housecats can kill adult rabbits.

Also adult weasels.

(Witnessed the results of both.)

Predators are behaviourally limited by what has been demonstrated to
them when they are learning how to hunt; there's evidence of this for
pretty much everything exothermic.  (Don't know about crocs and
monitors.)  You get peregrines in the middle of a grouse moor
preferentially eating ducks, you get house cats that have no idea how to
take small songbirds because no one ever showed them as kittens, and so
on.  Fully feral or wild small cats take a very broad range of prey.

In the case of anything fossilized, it is very, very, very hard to avoid 
theorizing in advance of the data, which is something we shouldn't do.

I'd also like to note that extant or recent high-predator-diversity
ecosystems have two things in common; multiple sizes of diverse large
herbivores, and at least some of the herbivores are migratory
herbivores.  This tends to suggest that unless both those conditions are
absent, we shouldn't be looking for predator/predator competition as an
extinction mechanism.

-- Graydon