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Re: Long, long last gasp. (fwd)




"Jaime A. Headden" wrote:
> 
> John Bois (jbois@umd5.umd.edu) wrote:
> 
> <Bats are easy targets for diurnal birds in the daylight--I don't think I
> can find the ref. but some sinister researcher released bats in the
> daylight. They scrambled for cover but nevertheless many of them were hit
> by kookaburra.>
> 
>   Ooo. Kookaburra are nasty birds altogether and highly territorial, so no
> wonder. Try this in North America, or Europe.
> 

Some of the smaller raptors (kites, etc) will prey on bats. In fact, in
some places they circle around the exits of bat caves around dusk, to
take advantage of the time when there is enough light for them to hunt
by, but not so much that bats don't feel comfortable leaving the cave.
Snakes will also literally hang around cave entrances, snatching bats
from the air at dusk.

Of course, flying foxes throw a spanner in the works. They often fly
about during the day. They also fall prey to raptors (and pythons), but
their vast numbers seem to work in their favour. It make you wonder
whether the vast size of microbat colonies wouldn't also work just as
well, perhaps suggesting that predator avoidance isn't the main reason
why bats are largely nocturnal. I suspect niche partitioning; perhaps
birds are better at catching the same types of prey as bats do, so bats
avoid direct competition by hunting at night. If so, then owls are the
union 'scabs' of the air!

-- 
________________________________________________________________

Dann Pigdon                   Australian Dinosaurs:
GIS / Archaeologist         http://www.geocities.com/dannsdinosaurs
Melbourne, Australia        http://www.alphalink.com.au/~dannj/
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