Icelandic sheep, the original highland hikers
The Icelandic sheep are let loose in the mountains every summer, this is a tradition over a thousand years old. Meanwhile the grass grows in peace in the lowlands, and is then harvested to feed the sheep over the winter.
Over the centuries the sheep have created an elaborate system of paths in the highlands, called fárgötur. If you have come across them, you might think that they've been made by hikers. That's not the case, human's aren't so organized that they take exactly the same path year after year.
Fjárgötur lie on the side of hills, in a valley, leading to an easy passage over a stream. They mark a line in an area covered with moss and heather. Some refer to fjárgötur as a scar on Icelandic nature, but they can also be seen as a witness to Icelandic agriculture.
They are very handy for a human hiker travelling in the highlands. Fjárgötur are roads through rough areas or through thick vegetation (on Icelandic standards).
In this video made by Icelandic Lamb, you can see the “sheep network”.