Re: Carnivore Energetics: Why Are Lions Not As Big As Elephants? .. and why aren't antelopes?

[john bois <jbois@verizon.net>]

>   Some large birds or crocs don't hide their nests at all: They either
guard
> them, or make it difficult for predators to get at the eggs. This includes
> ostriches, megapodes, and of course, the crocodile.

Ostriches, rhea, and emus are almost invisible on the nest (see Darwin's
description of inadvertently almost riding over rhea and Bertram, B. C. R.
1992.  The ostrich communal nesting system, for a description of the
difficulty of finding ostrich nests to study)
So...not ratites.  Regarding megapodes...most species that build large nests
do so on islands that lack continental predators--indeed, a paper (ref. if
needed) details islands in Indonesia.  Those with cats lack megapodes...and
next-door islands without cats have megapodes.  You are right about
crocs...but one could argue that they have a home-field advantage versus
would-be mammalian nest predators in the semi-aquatic niche.

> Some large mammals give
> birth in the open (whales and elephants) and defend their young
vigorously.

Yes..but these animals are outliers in mammalian size classes.  Most
terrestrial arms races are speed races.