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Re: Evidence for bat predation on birds



> Very interesting.... to balance matters, at least one
>  tropical eagle species routinely preys on the
>  outpouring of bats exiting their caves at twilight, as
>  seen on one episode of "Planet Earth".
>  --- Guy Leahy <xrciseguy@sbcglobal.net> wrote:

Yes indeed.  In fact, quite a number of birds of prey feed on bats.  Falcons 
(including peregrines, merlins, and hobbies) do so regularly, as do some owls.  
I would imagine that accipiters would take bats at dusk, as well, though I 
cannot recall if this has been officially reported.

There have been some published manuscripts that argue for a substantial 
raptorial influence on chiropteran evolution (especially with regard to the 
evolution of nocturnality).  Fairly recently, Speakman (2001) suggested that 
bats were ancestrally diurnal, and driven to nocturnality by the evolution of 
raptorial birds.  I am not entirely convinced of this hypothesis myself, but it 
is notable that Speakman sees raptorial birds as so well equipped to hunt bats 
that the entire early chiropteran lineage may have been selected for a 
photocycle change.  Speakman (2001) is not the first suggestion of its kind, 
either.  Baker (1962) and Neuweiler (1984) both addressed the importance of 
avian predation on bats, as did Fenton et al. (1994).

--Mike Habib


References:

Baker JK. 1962. The manner and efficiency of raptor depredations on bats. 
Condor 64: 500-504

Fenton MB, Reutenbach IL, Smith SE, Swanepoel CM, Grosell J, and Vanjaarsveld 
J. 1994. Raptors and bats - threats and opportunities.  Animal Behavior 48: 9-18

Neuweiler G. 1984. Foraging, echolocation and audition in bats. 
Naturwissenschaften 71: 446-455

Speakman JR. 2001. The evolution of flight and echolocation in bats: another 
leap in the dark.  Mammal Review.  31: 111-130