For the past few years I've been replacing all of my batteries with
rechargeables. I've started up spotlighting again and would like to
get a decent, cheap, rechargeable unit. I've read past threads and it
sounds like you can do fine spending a lot or a little.
I don't want to disturb the animals any more than possible and so
starting hunting around for information on red filters and the like. I
turned up a very interesting article from 1997 based on some research
Robyn Wilson did spotlighting for various tropical possums:
http://www.jcu.edu.au/rainforest/infosheets/possum_spotlight.pdf
The main points I gather from the article and a bit of other reading are:
* A brighter light was more disturbing to the animals.
* You saw _fewer_ animals with a brighter light because the light
reached the animals before you spotted them. With a less intense
light, you haven't scared the animals off so quickly. (Makes sense -
but I'd never thought of this before.)
* Clear, red, green filters - it didn't matter: anything that makes
the light less intense works.
That all sounds good, but what does it mean in practical terms when
buying a torch or a spotlight? That's what's got me writing in to the
list. Dr. Wilson compared a "30 watt" spotlight with and without a
filter. Unfortunately, watts aren't a unit of brightness so there's
really no way to know what to buy to be "30 watts or less", as the
article recommends. When I go to the stores, most cheap lights are
denominated in "candlepowers". While this is a unit of brightness, it
doesn't sound like it's a very good one and it doesn't readily convert
to other units. So, I think I'm after lumens...but haven't a clue how
many lumens I should be after. These days, the trend in torches seems
to be Brighter Is Better. I can imagine possums and owls falling out
of trees with some of these units...
Suggestions much appreciated!
P.S. Another blinding stroke of the obvious for spotlighting: Go out
when the moon is up. On a still night, even the slightest movement in
the trees is detectable without extra illumination. Of course, when I
tried this a few days back I wandered around in the woods for an hour
and saw nothing at all. (This is in a forest with Swamp Wallabies,
Brush-tail possums, Yellow-bellied Gliders, Sooty Owls, Powerful Owls,
and I don't know what else.) Are animals more wary when the moon is
out or was I just unlucky last time?
P.P.S. When possible, please reply to the list to make the archives more useful.
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David Adams
Wallaga Lake 2546 NSW
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www.birding-aus.org
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