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COMPETING BATS, BIRDS & PTEROSAURS
Pterosaurs and birds probably didn't compete directly, but as
pterosaur lineages died out, their ecological roles may have been
occupied by birds. So-called competitive replacement is probably rare
(see Benton 1996). On birds and bats, Ron wrote...
> Birds and bats coexist today, and some have suggested that this may
> be primarily because bats are, generally, nocturnal whereas
> relatively few birds are.
There is some suggestion from ecologists that bats are nocturnal to
avoid competition, mobbing or predation from birds. On some
Mediterranean islands which lack birds of prey, the bats are diurnal.
Day-flying bats are reportedly mobbed by hirundines. A _Nature_
article from 2000 (called 'Bats about the Arctic') discussed places
where there is 24 hrs of sunlight and vespertilionids and hirundines
hunt the same insects in the same place: it also addressed this issue.
These observations imply that birds outcompete diurnal bats when the
two coexist... maybe this is because bat flight apparatus is more fragile
than feathers or, more reasonably, that bats are inherently constrained
by their thermoregulatory abilities (bats overheat quicker in sunlight
and cool quicker in cold air than birds - obviously because of their
largely naked patagia). Could the same have been at all true of
Microbats probably hunt more in daylight than we realise: a large
recent study on pipistrelle stomach contents showed - to the surprise
of the authors - that dragonflies (which apparently only fly in the day)
made up a significant portion of items consumed (something like 40%).
Benton, M. J. 1996. On the nonprevalence of competitive replacement
in the evolution of tetrapods, pp. 185-210. In: Jablonski, D. H. E. and
Lipps, J. H. _Evolutionary Paleobiology_. Uni. Chicago Press.
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