Why the Laughing Cow laughs?

While looking for an R function for circular histograms, I incidentally found an arXived article that studies cattle alignement. I’ve often wondered why cows (very numerous in my native Jura) always look in the same direction. Does the wind bother them and make them look back? or do they all follow a leader? the usual question about cows in Jura is Why the Laughing Cow laughs, it is too much of a big new question not to be shared.

Actually, a theory states that cattle is preferentially aligned along geomagnetic field lines. Those lines are more or less north-south directed. To test that, there is a dataset available online that were collected by… Google Earth screenshots (!) from herds located in several European countries. They register in total the directions of a few thousands of cows.

The authors draw the conclusion that the cattle do not follow a north-south direction in general (see the histogram below). No more than any other preferred direction. But, at the herd level, the animals usually align along a few axes.

By the way, here is a link to circular density plots, and several others for wind rose diagrams, radial plots and stars networks. Anyone knows how to plot circular histograms like those in the article?