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Re: Carnivore Energetics: Why Are Lions Not As Big As Elephants? .. and why aren't antelopes?
Survival is certainly the overall resultant additive impact of many
isolated occurrences. Every characteristic that selects for survival
wins over those with no survival value in the long run by sheer
numbers of events in a population. I would agree that mobility would
be a plus in most situations except (for example) in baby animals
where being invisible or otherwise undetectable wins the day. This
holds true for both predator and prey species. Birds fall back on
other techniques such as mass nesting to overwhelm predators or
nesting in out of reach places. Then there are strategies like the
Night Hawk, which use single nest on the prairie. Their nests are
almost impossible to see blending in with vegetation and camo eggs.
Plus they buzz intruders adding to the distraction and the
effectiveness of the camo.
Small and fast will usually win the day over big and slow which is
why antelopes are not big (too lean and taste bad) and fast as heck
but they have to win 10 to 1. My jeeps on a road have trouble
keeping up with the antelopes up here on the high plains running
across open pastures. Lions (as analogue to predators in general)
have no reason to get bigger as they almost always take smaller,
weaker or sick prey. If not it is the whole pride hunting a larger
animal. A really big Lion would be a specialist indeed which is no
doubt why the American Lion died out with the retreating ice sheets
and the resultant change in prey diversity/size.
The way I understand it, gigantism is almost always a response to
some specific stabile environmental condition(s) causing co-evolution
of predator prey groups and relationships over quite a long period.
Comparing dinosaurian faunas and mammalian faunas seem to indicate
that this size relationship is usually attained by both predator and
prey. As for the croc example, a 16000 pound Deinosuchus (for
instance) could easily have taken a good sized dinosaur for lunch at
the water hole. Big prey leads eventually to big predators and visa
versa not to speculate on which came first (so to speak). It still
seems that larger predators would prefer to take smaller prey due to
the obvious dangers of attacking larger prey. It the prey was too
small, it could easily scamper away. Thus the survival of the
Antelope. The arms race turns out to be a legs race all too often.
Back to the original thread, I have never seen Antelope fight off
anything with horns as they prefer to run. I only have a few hundred
Pronghorn on the ranch and fortunately no Wolves yet so I really
haven't been given the right opportunity to watch their relationship
with a wild predator. I have seen never seen Pronghorn Antelope
pronk when they see me about. Maybe I don't look like a predator to
them. I have seen them use their horns on each other when they are
Frank (Rooster) Bliss
On Jan 21, 2007, at 1:02 PM, Anthony Docimo wrote:
Date: Sun, 21 Jan 2007 19:10:23 +0100
On 1/21/07, Anthony Docimo <firstname.lastname@example.org> wrote:
>Date: Sun, 21 Jan 2007 17:04:49 +0100
>On 1/20/07, David Marjanovic <email@example.com> wrote:
>> > this is a protection advantage not needed by mammals (who can
>> > simply run away with baby inside).
>Well, it's easier than running away with a nest ...
aren't pregnant females slower than non-pregnant females?
I imagine they are, but they're still more mobile than nests.
I harbor doubts that mobility is that important.....if it were, all
birds would be extinct.
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