Why do we recommend blue fences to protect sheep?
Why are the recommended fences to protect sheep from wolves blue?
You might think that it would be better to have a green fence perhaps, which is less of an eyesore to visitors and local people. But wolves, sheep and deer, like many other mammals in Europe, have dichromatic vision. This means they have two kinds of cone cells in their eyes – each type of cone absorbs a different colour (wavelength). The wolf, sheep, deer and other mammals cannot see green or red, so we use blue fencing to make it stand out in their environment.
In contrast humans have trichromatic vision. This means we have three types of cone cells, which give us colour vision. Birds have tetrachromatic vision so they have four types of cone cells!
Going blue
It’s for a similar reason that the roads in Austria and Germany have changed the colour of the wildlife warning reflectors from red to blue. These are the lights at the side of the roads that reflect vehicle headlights. By making the reflectors blue, it is easier for the wildlife to see, and if they are aware of the road they can avoid it. This means less roadkill, which is good for wildlife, and less road accidents which is safer for us and cheaper for the insurance companies and health services!
New blue Flexinet fences developed by Agridea and Eiger
Agridea together with Agrar Fachcenter Weddingstedt Fencemaster have developed new blue and white Flexinet fences in different versions. These are most often requested and recommended for high alpine situations. In a combination with shepherds and typical guard dogs are the 90cm single prong Flexinet fences. A 50metre roll weighs a little less than 7kg.
Especially for goats and in lower areas with no guard dogs, and where weight is not so critical there is also a 108cm flexing. This has two prongs and is more suited for less rocky areas. These weigh a bit more then 8kg per 50m roll. We use these in our emergency kits.
For more information and pricing: Herdenschutznetz OptiNet Blue 90cm, Einzelspitze, Vertikalstreben – 50m
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The common opinion at least for deer is another one: They (and other hoofed game) do see much better in the short wavelength range than in the longer ones. This means, they can see green, blue and violet much better than red, orange and red.
(That’s why the common tradition of hunters to wear dark red is really absurd…)
We’d love you to share! Unfortunately I did not come across any scientific papers on the subject, however there were news articles where there is reference to research taking place. For example in Germany http://www.spiegel.de/international/europe/germany-tries-to-curb-roadkill-problem-a-911591.html
Super interesting, thanks for sharing! I think that here, in the Netherlands, most of the wildlife reflectors are still red. Or at least, I have not seen any blue ones yet. I’ll share this with our local nature managers. Do you know if there are any scientific papers written on this subject?