On Mon, 22 Jan 1996, Herb Curl wrote:
>
> Jim Russo has been favoring us with an essay on owl vision. What I've
> missed so far is a statement concerning their alleged ability to see light
> in the near infrared, and thus locate warm prey that would appear lighter
> than the cooler background.

No evidence to suggest that owls can see in the infrared (IR). The
following behavioral experiment indicated that in darkness it is sound
rather than IR vision that is used:

Payne, R (1971) Acoustic location of prey by barn owls (_Tyto alba_).
Journal of Experimental Biology 54:535-573.

Payne put a barn owl in a completely dark room with a mouse. The barn owl
was able to catch the mouse. Then, to test whether the owl was using
infrared or sound cues, he attached a small piece of paper to a string
attached to the tail of the mouse. The owl now struck at the paper (which
rustled louder than the mouse feet) rather than the the mouse.


I believe that there is also operant conditioning evidence that owls do
NOT see in the infrared (you can train a bird to respond to normal visual
cues, but not to IR cues), but I am not familiar with the literature.

In fact, I know of no example of a bird that can see in the infrared.
That doesn't mean the ability doesn't exist somewhere - until recently it
was believed that ultraviolet was invisible to most organisms except bees,
but it turns out that UV vision is pretty widespread, including among some
birds (hummingbirds, e.g.). But at this point, the evidence seems clear -
Owls can't see infrared radiation, and don't use it to detect prey

Chris Hill
Everett, WA
cehill at u.washington.edu