Reindeer See a Weird And Wonderful World of Ultraviolet Light

In the Arctic reindeer we have got one animal who has adapted itself so well to its visual environment it is using bits of visual information that we can't see and it makes sense to the animal. My name is Glen Jeffery and I am from University College London and I'm a visual scientists. I am interested in vision, how we see the world and how other animals see the world because very often they see a very different world from us. The Arctic reindeer is an animal that has an extreme visual world because for three months of the year it is completely dark and for three months of the year it is bright for 24 hours a day. When you are in the Arctic you get a lot of scattered light particularly when the sun is just around the horizon. When that happens the scattered light becomes very very blue. For us, we stop seeing in the violet but for some animals, very very few animals, they see down into the ultra violet, into a much much deeper world. We don't see it. So one of the questions that we had was do these animals up in this environment actually use UV? Do they use ultraviolet light? So far the only mammals that we know that do that are actually a few rodents and a few bats; it is not common, it's very uncommon. The interesting finding that we had was that Arctic reindeer see deep into the UV. By using UV light that we cannot see at all they're actually managing to avoid the animals that are likely to eat them, look at the world and see objects they want to eat a hell of a lot more clearly coming through the snow and the ice and they are also able to look at the signals and messages left by their own type of animal and different types of animal by being able to find their urine. We went up to the Arctic with two cameras sitting next to one another. One camera could see in the UV and one camera saw the normal visual world that we did. So the idea would be that we see what we see and then sitting next to it, hopefully we see what the reindeer sees. To do this properly we wanted to follow a herd of animals through the snow seeing what they see and the great advantage here was that the Norwegian army gave us a 'go anywhere' vehicle that we could pile all our equipment into and follow a herd. The answer was really interesting. The world in UV is rather different but it's different in a subtle way. First thing was that their urine was very very dark in UV so what we would see as a very very light smear on the snow they saw in enhanced contrast - it was almost dark grey on white. So they could see where other animals had been peeing and maybe that is a big advantage for them because they'll then go over it and they'll smell it, they'll derive information about the other animal from being able to identify it. The other thing that was actually quite impressive was that many of the lichens that they love, some of them would do almost anything for a certain kind of lichen. When you shine UV light on it, it goes black so if you have got a little bit of lichen sticking up through the snow it looks like a bit of grey on a white background but not to the reindeer - that's actually black on white, it's a hard contrast image so that really helps it. An interesting thing also, is that these animals, when you look at them in UV, when you point the UV camera specifically at them, you actually find that their fur absorbs UV and also they'll see their predators. A natural predator for them up there historically would have been the wolf and the wolf's fur absorbs a lot of UV.