Hello again ! (and berry question)

[Jim Lloyd]

Jim: I do find it difficult to be fully convinced that this would have that much influence on bird foraging, given that (as I mentioned before) UV levels in nature will be relatively low and there is contrast in the visible anyway.

 

You have a visible photo and a UV photo of the Vaccinium berries. But now you must create some kind of bird-view photo. Here's my quick-n-dirty attempt at that.

 

The berries absorb UV and reflect blue (rather dark blue) where there is no bloom. They reflect UV where there is bloom and also appear to reflect a very pale blue (in the original photo) where there is bloom. So, given that the bird has blue receptors and UV receptors, then there are two bird colours (to oversimplify a bit) detected by the bird. The two colours would be Blue and a bird colour we will designate as Blue+UV. We can represent the bird's Blue by simple visible blue. But we cannot represent the bird's Blue+UV easily. I usually create a jumble pie of colours to represent any insect or bird colour which contains reflected UV.

 

When I put Blue and my jumble pie version of Blue+UV over some of the berries in your photo, it looks like this.

 

 

Now, I grant you that I might have over-dramatized my interpretation of the bird's view of the berries. But it does prod one into realizing that the bird is detecting two distinctly different colours on those berries. Of course, we will never be sure about how the bird sees. Does a bird actually form "brain images" of what it sees? Or is a bird's vision specialized to its needs in such a way that images are not necessary? Maybe the researchers will figure it out someday.

 

Thanks Andrea! - that's a cool way of looking at it!

 

I doubt that birds see images as such and I don't think we do - I think that idea is known as the homunculus fallacy (open to debate of course!)

 

But making images can still help us understand how they do see ...

[Andrea B.]

Agreed!

 

I enjoy these attempts to model the vision of other creatures. It does give us insights. And leads us to the appreciation of alternate visions of the world.

I've been trying to sometimes use the word "detect" instead of "see" to make the point that what we call a visual receptor may not be associated with vision in the sense that humans understand it.

 

I've only dug (somewhat) into "bee vision", so I liked that bullet list above about "bird vision".