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msar-riders - Re: [MSAR] colors

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Subject: Mounted search and rescue

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  • From: Una Smith <una.smith@att.net>
  • To: Mounted search and rescue <msar-riders@lists.ibiblio.org>
  • Subject: Re: [MSAR] colors
  • Date: Mon, 4 May 2009 08:52:58 -0600

Joe Kinch's comments about the difficulty of reading topo maps at night are
important. To discriminate colors on topo maps at night requires a fairly
bright light, one that interferes with the map-reader's dark adaption. So
if map reading, either use lights, or have the map reader move away from
the rest of the group and shield dark-adapted eyes from the light. To move
at speed in the dark without lights is safe if the trail is clear at head
height, but if moving through forest undergrowth you need to be able to see
tree limbs. This is especially true when on horseback. I generally prefer
to work without a light but there are times when I do need to use one.

I am interested in the idea that red light allows for map reading without
as much interference with dark adaption. Those of you who use red filters,
do you worry at all about the frequency range of the light passed by the
filter?

Joe is correct also about people becoming very nervous, detecting movement
in the dark nearby. The fear of being stepped on is considerable and can
be overwhelming. I have experienced this myself during years of fieldwork
in tropical forests. Most nights, due to the typically heavy vegetation
and cloud cover, there was too little light for humans to see in the dark,
no matter how well dark-adapted our eyes became. To catch bats, we would
put up net curtains, then sit in the dark. One night as my eyes became
dark adapted I saw a stick covered with bioluminescent fungi. I picked it
up ... and the biologist sitting beside me screamed! He had been looking
at the stick too and was spooked when it suddenly moved toward him. One
other night, I was alone with my flashlight off, when I heard crashing and
snarling. I thought I was about to be attacked by a pack of dogs. Turning
on my light, I saw a family of pecaries (related to pigs) eagerly rooting
in the leaf litter.

Una Smith
New Mexico




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