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There have been many reasons put forward for animals avoiding power lines. But a collaborative research project has provided radical new insight into animal behaviour

It’s long been recognized that animals avoid power lines, and there have been many explanations for this but the idea that ultraviolet light may be a factor is genuinely new. The study, with its ecological implications, was a testament to the creative insight born from a multi-disciplinary scientific collaboration between experts from the UK and Norway. 

Funded by the UK’s Biotechnology and Biological Sciences Research Council (BBSRC) the group comprised researchers from University College London (UCL), Moorfields Eye Hospital, London, UIT The Arctic University of Norway and the University of Oslo in Norway. The research actually came out of a separate project looking at ultraviolet vision in reindeer explains Professor Glen Jeffery from University College London’s Institute of Ophthalmology. ‘We had been working for a long time up in Tromso, mid-summer and mid-winter, with visual scientists. The main issue was how did these animals cope with long periods of darkness in winter, then long periods of bright daylight – 24 hours a day – in summer. That’s a big vision problem. We took a sideline because we discovered the animals saw ultraviolet.’

Seeing Ultraviolet

This opened up new areas to explore, an opportunity enabled by the fact that the team have been engaged in a long-running project with the University of Tromso. Dr Nicolas Tyler, an ecologist at UIT The Arctic University of Norway, and another member of the team, had been researching how the seasonal animals in the North adapt to constant daylight and then the absence of daylight. ‘Animals mating in the autumn, or changing their plumage in the spring, don’t have a daylight signal of light and dark changing daily to act as a clock, as a calendar for them.’ The short answer according to Tyler is that seasonality is controlled by the body clock. As part of this research they became interested in the idea that reindeer see ultraviolet light, and they then brought other researchers out into the field who took photos in the twilight, ‘and to our astonishment,’ says Tyler, ‘we found that plant material absorbs ultraviolet light very, very strongly, snow reflects it very strongly. So for us humans we see plants in snow in twilight as grey plants against a dirty white background. In ultraviolet light the plants are black and the snow is white.’ Ultraviolet vision enables the reindeer to see food. It prompted the question from Nicolas Tyler to the team, do power lines produce ultraviolet light? 

Most importantly, in unpacking this question, they ‘got all the right people in the room,’ explains Glen Jeffrey. ‘I am a Visual Scientist. Chris Hogg,’ from Moorfields Eye Hospital, ‘is a Visual Scientist but he works on recording from the eye.  Nicolas Tyler has been studying reindeer for years. We also got a high-energy physicist into the room from Oslo University and we got Karl-Arne Stokken who is more of a physiologist.’ They plugged together these different areas of knowledge and delivered a solution. Power lines emit ultraviolet, they knew the animals were sensitive to a spectral range of ultraviolet, it seemed obvious the animals were seeing and avoiding them. 

There had always been alternative reasons as to why animals avoided power lines, not least that the forest or jungle cleared away offered no protection from predators. But with the reindeer another explanation was needed says Tyler, ‘because reindeer live in the far north, where in the tundra, there are no forests,’ and therefore no clearings needed for the power lines and the reindeer still avoid them.