Ultra vision debate
I found Dominic Couzens’ article on Kestrels interesting, but was surprised to see him claim that they follow the urine of voles because of their ultra-violet vision. I recently heard a talk titled “Through Birds’ Eyes” by Graham Martin (former vice-president of the BOU, editor of the journal Bird Study, etc) and he categorically stated that this was a myth and the original claim had been disproved. Is this true? Peter Evans, via email
QScientists have long thought that several species, among them Blue Tits, Buzzards and Kestrels, have some sort of sensitivity to ultraviolet light, and this has been shown to be true in many studies. However, the degree to which these birds can actually ‘see’ in ultraviolet is still debatable. Experiments have indeed shown that Kestrels are more likely to follow vole urine trails that are highlighted with ultraviolet light in preference to those that were not highlighted. This shows that the species does indeed have the capacity to see at least slightly in the UV part of the spectrum, but according to some more recent research this ability may be of little use when it comes to hunting voles whose trails have not been highlighted. So the answer at the moment may be that yes, Kestrels can see in ultraviolet, but not well enough for it to be any real help.
Kestrel Yucatan Jays We’re sure it’s a Knot