This is one of those articles that I can imagine coming to mind 10 years down the road when I'm looking at something weird and suddenly thinking "Ooh, that's what I'm looking at!"
So it works kind of like ants, who leave trails for other ants to follow?
They are making gradients for themselves. Like a cow eating grass and constantly moving by a gradient of grass mass per area. Or moving away from cow excrements. It is funnier with a herd of cows, because they will hold a line, moving always forward from excrements to grass.