Re: Do deer and elk see in color.

Lane,

Thanks for your question.  The first thing I would like to point out is 
that it is a mistake to assume that animals either have colour vision or 
they do not.  There is a broad range of degrees of colour vision, and even 
animals which seem to be able to recognise the same colours we do, are 
unlikely to see the world in the same way.  Even within our own species, 
you know that many people are colour-blind to varying degrees, with 
minimal effect on their everyday lives.

There are two types of light-receptors in mammalian eyes.  "Rods" which 
detect only levels of light, and movement, in monochrome, and "cones" 
which can distinguish colours.  Rods are much more sensitive, especially 
at low light levels, and are thinner, so that more can be packed into a 
small area, giving greater visual acuity.  

It therefore makes sense for "prey" animals like deer to have mostly rods, 
so that they are sensitive to movement and see more clearly at night, when 
they are most active.  Studies of deer eyes have shown that they do in 
fact have some cones, but nowhere near as many as we do, so they probably 
do have some colour vision, but perhaps something like a "colour-blind" 
human, and only in bright light.  It is interesting to note that some 
hunters in the US are now wearing orange caps or jackets to prevent 
themselves being shot by their friends, but with no apparent effect on 
their visibility to their prey.

PS Don't feel sorry for the deer - my colourblind friend tells me that he 
sees many more subtle shades than me, and think he has the better deal !