Bernie,
There's some older commentary on noise from flowing water affecting foraging
by bats. In
1986 Herd reported on noise from fast and slow flowing water (up to 80 kHz),
noting fast
flowing water was louder up to about 70 kHz. He discussed two species of North
American
Myotis that often hunt near water and pointed out that the species with the
higher typical
echolocation frequency (50 kHz) was commonly encountered hunting over fast
while the
other (40 kHz) was not. This is not exptl study like the one Gianni mentioned,
so other
factors could be involved.
I also wonder about long term hearing damage from human noise exposure in bats.
Bats
have some elaborate musculoskeletal skull structures described as minimizing
the risk of
self deafening when they emit calls in excess of 100 dB. However, some roost in
degraded
highway expansion bridges with large pieces of steel striking one another every
time a
large truck tire strikes the loose plate on the deck. No measurements, but I
can attest
these noises are painfully loud in the more open area below the roost. Unlike
their own
calls they may have evolved no neural warning circuits to prepare for these
very frequent
events.
This leads to recalling another biologist's anecdote on realizing the foxes
living and
hunting near the ends of a jet runway at Los Angeles airport were deaf.
Bill R.
>
> I don't know if anyone has looked at typical bat habitats to see if
> there is any link to the geophonic (non-biological natural sound
> generated in an environment) or other biophonic material. A few of the
> spectrogram I've generated show pretty clearly that the bats tend to
> find their own frequency/temporal niches, much as one would expect
> with this thesis.
>
> Bernie
>
>
> On Nov 14, 2008, at 7:11 AM, Gianni Pavan wrote:
>
> > Hi Bernie, I did similar thoughts. It is very likely that low
> > frequency human noise doesn't affect echolocation directly (by
> > masking for example). However, I'm wondering about any other possible
> > effect not necessarily linked with high frequency echolocation.
> >
> > Gianni
> >
> > At 15.42 14/11/2008, you wrote:
> >
> > >Got some considerable stuff on large mammals, frogs and insects, but
> > >not bats, Gianni. This is probably because, except for the high whine
> > >of jet engines and some turbines (that tend to disperse the greater
> > >the distance from the source and is more typically industrial noise
> > >generated in enclosed spaces) there isn't a whole lot of anthrophony
> > >(human noise) that extends out into bat ultrasonic range. Recent
> > >recordings I've made with distant traffic and aircraft (both light
> > and
> > >commercial) haven't shown much, if any, impact for those reasons,
> > most
> > >likely. These are either hoary or Myotis.
> > >
> > >Bernie
> > >
> > >On Nov 14, 2008, at 12:31 AM, Gianni Pavan wrote:
> > >
> > > > hi all,
> > > > lately I'm getting interested in the impact of noise on natural
> > > > habitats. Effects of noise on birds and frogs is known.
> > > > But what about bats ? Please let me know if you have any info or
> > > > literature reference about the topic.
> > > >
> > > > Gianni
> > > >
> > > > ----------------------------------------------------------
> > > > Gianni Pavan
> > > > Centro Interdisciplinare di Bioacustica e Ricerche Ambientali
> > > > Universita' degli Studi di Pavia, Via Taramelli 24, 27100 PAVIA,
> > > > ITALIA
> > > > Phone +39-0382-987874 Fax +39-02-700-32921
> > > > Email <gpavan%40cibra.unipv.it>
> > > <gianni.pavan%40unipv.it>
> > > > Web <http://www.unipv.it/cibra>http://www.unipv.it/cibra
> > > > ----------------------------------------------------------
> > > >
> > > >
> > > >
> > >
> > >
> > >
> > >Nessun virus nel messaggio in arrivo.
> > >Controllato da AVG - http://www.avg.com
> > >Versione: 8.0.175 / Database dei virus: 270.9.3/1786 - Data di
> > >rilascio: 13/11/2008 18.01
> >
> > ----------------------------------------------------------
> > Gianni Pavan
> > Centro Interdisciplinare di Bioacustica e Ricerche Ambientali
> > Universita' degli Studi di Pavia, Via Taramelli 24, 27100 PAVIA,
> > ITALIA
> > Phone +39-0382-987874 Fax +39-02-700-32921
> > Email
> > Web http://www.unipv.it/cibra
> > ----------------------------------------------------------
> >
> >
> >
> >
>
>
>
>
|