Researchers suggest wild animals avoid power lines due to UV light emittance

Mar 13, 2014 by Bob Yirka report
Credit: Tony Boon/Wikipedia

(Phys.org) —A team of researchers from several institutions in the U.K. and Norway has published a paper in the journal Conservation Biology suggesting that the reason wild animals avoid power lines is because they are bothered by visible UV light. Humans cannot see UV light, and have thus been mystified as to why deer and other animals avoid power lines and the sometimes large frameworks that hold them.

High-voltage are a source of UV light due to a build-up of ionized gas—when it suddenly dissipates, flashes of UV light are emitted. The larger the buildup and release the larger the flash. Power companies try to minimize such build-ups as they indicate a loss of power, or inefficiencies in a line—they use special goggles to find and repair large problem areas. Normally people only become aware of the flashes when they hear cracking or popping noises, particularly in winter.

Many animals (approximately 35 known species) on the other hand, are able to see UV light in all its glory, and most of them appear to find it alarming in power cables. It tends to cause fragmenting of species, problems with grazing and a reduction in populations. Prior to this study, it was thought that perhaps animals avoided power line paths due to the openness of the terrain created when trees are removed. In this new effort, the researchers note that one species of animal, reindeer, appear to be particularly sensitive to the UV light. Not only can they see UV light (normally used to help find plants buried beneath snow) but their eyes are particularly sensitive to it because of the long dark winters. They see the UV light as random flashes lighting up the area (made worse when it bounces off snow and ice) accompanied by popping noises. It's enough to cause the animals to stay away from lines and structures—they won't walk under them, leaving them cut off from land on the other side. The problem has caused herders in Norway to be at odds with power companies over construction of new lines.

Scientists have noted a tendency for animals to avoid power lines in places all over the globe, but were confused as to why—power lines are high enough to avoid contact and few people are around once they are put up. Some have suggested it was due to clear cutting vegetation, but in areas where there is little vegetation to begin with (such as reindeer habitat) have avoided them as well. More studies will have to be done to conclusively prove that it's UV light, but at this point, it appears likely.

Explore further: Researchers find UV sensitivity in wide range of mammals

More information: Tyler, N., Stokkan, K.-A., Hogg, C., Nellemann, C., Vistnes, A.-I. and Jeffery, G. (2014), Ultraviolet Vision and Avoidance of Power Lines in Birds and Mammals. Conservation Biology. doi: 10.1111/cobi.12262

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tadchem
not rated yet Mar 13, 2014
The human cornea filters out a lot of UV light. After mine were replaced with artificial (silicone), UV-transparent lenses due to cataracts, I found my retinas responded (unpleasantly) to UV-A, necessitating frequent use of sunglasses outdoors.
On the positive side, the UV-A seems to be involved in chemosynthesis of melatonin in the retina, keeping my circadian rhythym well syncronized to sunlight.
Bonia
Mar 13, 2014
This comment has been removed by a moderator.
adam_russell_9615
not rated yet Mar 13, 2014
UV is bad for your eyes. Absorb enough of it and your lenses will be damaged.
nkalanaga
not rated yet Mar 13, 2014
I wonder if they could find a way to use this to prevent birds and bats from flying into the lines? Maybe coat the wires with something to change the UV wavelength to one the fliers can see?

Bonia: Possible. It could also be the noises. They could be more sensitive to the "cracking and popping" than humans. At least in the case of cows I doubt that it's the UV, as they're active mostly in daylight, and probably wouldn't notice it over the sunlight. For deer it could well be all three reasons.
Benni
not rated yet Mar 14, 2014
In my first job out of college, I worked in the Meter Engineering division for a major U.S. mid-west power company, my job title was Meter Engineer. It was our job to use instrumentation to detect & find the sources of "stray voltages" along the power grids & sub-stations.

Stray voltages occur due to induced voltages created by the amperage carried in conductor cables. Every conductor cable carrying any level of current is surrounded by a flux field. A current carrying conductor passing through or near a structure also capable of conducting current, causes that structure become a "current transformer". Stray capacitance discharges occur when induced voltages in towers build to a level that cause them to discharge to ground.

When these discharges occur, electro-magnetic wavelength emissions occur across the entire EM Spectrum, not just UV. Drive your car near one of these conductor towers with your radio on & listen to the radio influence voltage (RIV) drown out your radio.
Eikka
not rated yet Mar 17, 2014
When these discharges occur, electro-magnetic wavelength emissions occur across the entire EM Spectrum, not just UV.


That's technically not true, as the energy required to make e.g. roentgen or gamma rays is much larger and would require a vacuum gap to accelerate the electrons to sufficient speeds. The interference you hear on the radio is higher harmonic oscillations of the fundamental frequency of the discharging L-R-C equivalent circuit, and they diminish with increasing frequency.

The UV light in particular is emitted by ionized gas molecules that release their energy at particular wavelenghts, not at all wavelenghts. The stuff responsible for the UV emissions is nitrogen: http://www.daycor...trum.jpg

A car radio with an antenna sticking up is exposed to an oscillating electric field of about a thousand volts per meter under a high voltage line anyways, so the antenna itself will ring with the voltage and mess up the reception.