I don’t know why I never heard about this until today, but apparently the world’s pastures are being eaten alive by throngs of bovine compasses. See the news story or study.
All over the world, apparently cattle herds tend to orient themselves along a north-south axis. They’re even affected by magnetic declination and high-voltage power lines.
I can understand the use of magnetoception in migratory species or ones that travel over long distances, but… why cows? Why?! 
Mu
A 2011 followup study debates the findings, but a third party commentator says that the original results, “while mysterious, still stand”.
That article also contains what is now possibly my favorite phrase: “cows with unsatisfactory resolution”
could be interaction with the cow magnets.
Some wild bovids such as the bison and wildebeest are migratory. Are domestic cattle descended from a migratory ancestor?
Modern cattle ranchers discovered a while ago that using electrified fencing and cattle prods was the most efficient way to get them to stick to the fridge.
Additionally, red meat is very high in iron.
How attractive do you find them, exactly?
fucking cow magnets, how do they work?
I can’t stand the Insane Cow Posse.
Growing up o our farm in west central Minnesota, the horses grazed facing south or east, mostly.
But not because of a magnetic sense effect. It’s just that horses graze with their tails into the wind, and the prevailing winds on our farm were from the north or west.
Possibly the same is true of cows – they tend to graze oriented based on the wind direction. And wind direction is fairly constant in most locations.
Hrmm, could be something to that.
Here’s a cool “wind map” of the US that indicates wind direction from day to day.
Let it load for a minute, it traces out wind currents across the map; the results are actually really cool and fascinating. Makes America look furry.
Is it so the breeze doesn’t blow their tail hair back into their butts when they poop?
Hehe, there’s a cowlick in Nebraska right now.
Golf clap
I feel it deserved at least that much attention. However, the fact that there’s no element with the symbol Mu does rather spoil the joke, tragically.
Golf clap
I feel it deserved at least that much attention. However, the fact that there’s no element with the symbol Mu does rather spoil the joke, tragically.
Instinct for protection against predators? I’d buy that.
Oh it was better than that - μ
Has the study taken into account that the path of the Sun is generally E-W? So if you want to be warmed up by it, it pays to have your flanks to it.
That’s what I was going to say… but then you’d expect the cows to rotate throughout the day, facing roughly N-S at sunrise, then E-W at midday (at which point the sun will be in the south, in the northern hemisphere), then back towards N-S at sunset. Of course, the sun doesn’t set due east except on the equinoxes, so the bovine angle would change through the year.
Are there any large herbivorous grazing animals in temperate climates which don’t migrate?
AFAIK, the only grazing animals that don’t are either native to tropical climates that don’t have seasons or are too small to migrate. Anything that can, does, which makes sense the evolutionary pressure would have strongly favoured animals that moved north into the vast pastoral tundras in the north of europe in summer and then south into warm climates in winter.
Maybe there’s no direct evidence but it seems to me pretty clear that the Aurochs would have had to migrate and so modern cows have some residual trait of a migratory urge.
