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Re: bats




On Sun, 29 Dec 2002, Paul Sparks wrote:

> There is a lot of comments about bats and birds competing for the same nitch
> where I don't think that competition exists.

This is too narrow a definition of competition.  Competition can involve
_any_ aspect of a niche.  Too often we limit the idea to head to head
competition for food.  The classic competition between Balanus and
Chthamalus barnacles involves substrate.  The amount of food available is
not limiting, it's the ability of a barnacle to find a rock to hold onto
so it can access that food.  In the same way, there may be plenty of food
available for bats in the daytime, but they can't tolerate the predation
regime.  And so, in relation to the solar illumination aspect of these
flying vertebrates' niches, bats are outcompeted by birds because the
latter can access illuminated resources.  On the other hand, for an
entirely different set of reasons, bats have it over birds at night.