The Great Canadian Beaver Migration

A few weeks ago I was fortunate enough to witness one of nature's more inexplicable phenomena. As the sun wrestled with the horizon, I saw the a beaver migration along the edge of the highway. And what a sight it was! One long single file of our nations symbols stretching back for almost a mile, which I believe is about a kilogram and a half, or as I've heard it called, a kilowattever. They were earnestly galumphing along the asphalt, their portly bodies swaying back and forth in perfect rhythm. As you can imagine this is not a spectacle one sees everyday, in fact most Canadians are lucky to witness it even once in their lifetimes, so I was fascinated. They seemed to be in individual family groups according to size, so I assumed that the leader of each unit, also the biggest, was the patriarch or possibly the matriarch, I'll have to look that up.
It is not understood why they form these migratory groups, and all documented studies simply gloss over the motivation of the creatures. What is known is that they never migrate north or south, it's always east to west or vice versa. This may be a recent development in their pattern, as few roads tend to go very far north, and are usually not in the best condition, generally with gravel edges which the beavers find most uncomfortable, especially the younger males, as it is said to stunt tail growth, which makes them disinclined to even make the mysterious trek. The beavers encourage each other with frequent slaps of their tails on the pavement, and this also may explain their preference to modern highways over the gravel roads which service the North.
They can sometimes be seen formed into sleeping circles where they all rest together with their heads stuck in towards the center and their tails fanning out to form a perimeter, sometimes piled three or four deep. This is when they are the most dangerous and are better left alone. The larger males guard the resting rodents and are very aggressive in their defence. I lost an Uncle this way as he was taken down by several circle defenders and succumbed to the numerous bites. The sad thing about this situation is that the beavers who attack humans must be singled out and put down. Once they acquire a taste for human flesh they will not return to gnawing on trees for their living, and have known to terrorize outpost communities for months at a time before they are stopped.
Why do they make this trek? No one who lives among them seems to know. Science has no idea, and you sure can't ask a beaver, can you?