From: bell-peter@yale.edu (Peter Bell)
Newsgroups: rec.pets.herp
Subject: Re: Gratuitous Kills
Date: 23 Dec 1992 21:23:26 -0500
Organization: Yale University Science & Engineering UNIX(tm), New Haven, CT 06520-2158
NNTP-Posting-Host: minerva.cis.yale.edu

In article <1992Dec23.230249.10006@progress.com> gerard@progress.COM (Gerard Bras) writes:
>pholland@iastate.edu (Paul J Hollander) writes:
>
>...regarding whether white mice smell funny
>
>>I'm not sure whether vision or scent is involved.  That's why I'd like to see
>>someone try feeding in darkness.  If there is still a preference, then 
>>something more than vision is involved.
>
>Well, I've fed snakes in the dark.  Sometimes a snake that won't feed well
>during the day will take food at night.  I can't say that I was looking for 
>this kind of info so I don't really remember whether white items got eaten
>more readily when the lights were down.  I have definitely seen aversion to
>white strains though, I though it was just my luck but it really caught
>my attention when this thread popped up. 
>
>>>Am I correct in thinking that white rodents are man-made strains?  
>>Or possibly a minor change in the smell is another effect of albinism.  We
>>know that it produces changes in the brain, as well as making the fur white.

>much better than ours and thier vision is nothing to brag about.  For people 

Actually, snakes have reasonably good vision, and a fair amount of forebrain
devoted to handling it.  In addtion, the boids (and several other families)
have exquisite infrared sensitivity, which is coextensive with the visual 
space maps in the brain in rattlesnakes, where the mapping has been looked 
into.  I am not sure, but I believe that the infrared could tell the animal
what color the prey was (all white versus all black) since the different
colors of fur might well have slightly different heat radiative/absorbance 
characteristics.  I don't think that corn snakes are ir sensitive, though....

In the wild, white mice are very rare.  Long ago  I read a study where 
owls in caged runs were presented with white versus black mice;  the white
mice got eaten in a hurry by the owls, probably due to their greater 
conspicuousness against a natural background.  The authors presented this
as one reason why light-colored mice are rarer in the wild;  full albinism 
is heavily selected against as it usually creates a lot of other problems, 
like early blindness and difficulty attracting mates.

I have also seen the black > white preference behaviour, and I attributed it
to visible light at the time, although the snake was a boa, and could have 
been using ir cues as well.  Odorants may also be important--I would be 
surprised if there were not odor cues that differed between melanistic and 
amelanistic mice....  Probably, all cues that are available are used by the
snakes, and they do not recognize white mice as fitting the pattern for food 
as well as black mice do, having not evolved in a situation where white mice
were abundant....

Peter
bell@minerva.cis.yale.edu
(want to read more?  A start is Dorsal Ventricular Ridge by Phil Ulinski--use 
the index, though, then go to the interesting sections for pointers to the 
original literature.  Published in 86 by Wiley Interscience)