I need a wee - which way's north?

We've talked before about the Ig Nobel awards (see 2/10/11) and this year the biology prize has been awarded to a team who documented dogs' behaviour when they urinate, and established that when they do so, they tend to align themselves with the earth's magnetic north/south axis.  So if you're lost in the woods, and there's no moss on the trees to help you establish north and south, just watch out for a dog having a pee!