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bat info was Re: Orenstein's pedestrian arguments.



Maia wrote:
> How many diurnal  mammals are there on the small-animal
> niche?

Once we agree how small is small in mammals (I'm assuming anything
cat-size or smaller) -There are squirrels for sure, but most everything
else I can think of is either twilight-active or active throughout night
and day in patches (both nocturnal and diurnal like cats). How many can
you think of?
 
> Some birds and a few mammals (hares) make hiding places on the
> ground were they stay when they are not active. Are the few bipedal
> mammals able to dig holes?

well, people can, the African Bushmen dig out hibernating animals using
little more than sticks.  I don't believe the other primates do except
to demolish terite mounds, not to burrow.  But bears will dig out
burrows out of existing crevaces for hibernating, and polar bears dig in
snow-but bears aren't fully bipedal.

> I don't understand the reasoning... Being able to fly to evade
> predators and being able to walk efficiently to forage is a big
> advantage. Birds took over the ground diurnal micro-niche, probably
> if bats capable of walking and flying efficiently could evolve they
> would take most of the ground nocturnal micro-niches also. As I see it
> one of the advantages of being small is that it allows for efficient
> diurnal/nocturnal specialization, you just hide/stay quiet during the
> rest of the day. One can not really compare strategies between birds
> and small mammals.

there are already bats that ground-hunt, the one I've been particularily
interested in is Antrozius pallidus, the Pallid Bat which is a colony
crevice-dweller which hunts solitary and primarily feed on large ground
insects that it apprently spots while echolocating in the air, then
lands and HUNTS THE PREY ON THE GROUND.  It feeds primarily on scorpions
(to which it is immune to the venom in the stinger), centipedes, and
other large, ground-dwelling bugs and the occasional small lizard.
Bats are also prey for owls, so bird vs. bat competition has additional
help in keeping bats under control.
Now if there was a predatory bat large enough to be a hawk or owl
equivalent, we'd be talking!

-Betty