Subject: Re: Lighting the Bridges
Date: Nov 20 10:07:39 1998
From: Don Baccus - dhogaza at pacifier.com


At 10:21 PM 11/19/98 -0800, Nancy Creighton wrote:

>Back in 1981 well over 1000 papers had been written about this subject, so
>this summary does not do all views/opinions on the subject justice. But I
>hope it provides a quick answer, and for more serious students a starting
>point.

This still doesn't really address the issue: will lighting the bridge cause
an increment in confusion-caused mortality over the present status? I'm
assuming, for instance, that the bridge already has streetlights on it,
that there is traffic on it and that most of the drivers, at least, have their
headlights on while driving across, etc. I'm not familiar with the bridge
under discussion, but in the case of the wastefully lighted bridges in
Portland
they're already surrounded by tall, lighted buildings and structures and
the waterfront is bordered by a lighted park, so in the case of these
bridges I very much doubt that the very small incremental increase in
light, especially light visible to a flying creature, adds to existing
mortality.

I certainly don't doubt that some lighted structures can cause high levels
of mortality, and I've heard of isolated cases such as the TV tower you've
mentioned.

Proving that some lighted structures cause high levels of mortality is a
long, long way from showing that ALL lighted structures cause such mortalities
and even further from showing that adding lighting to a structure which
already
has lights will add to whatever mortality is already being caused.



- Don Baccus, Portland OR <dhogaza at pacifier.com>
Nature photos, on-line guides, and other goodies at
http://donb.photo.net