animals have no intellect to understand the reasons, but they feel the quieting radiations coming from the north and vitalizing currents from the south. instinctively they feel it's best for the circulation of their current of life when they build their nests in a north to south direction and when they sleep this way.
the north side of trees are often covered with moss, so trees also have their face towards north. if you want to know more about the 4 winds and the 4 faces of god (zodiac), read ezekiel 1 in the bible.
a person who is seeking connection with God and praying should face north or east, but never south or west. In the north and in the east he can find forces that lead him towards spiritualization, whereas in the south and in the west he finds stimulation which leads his consciousness to identify itself with his sensual instincts.
animals are closer to god than humans because they haven't eaten the forbidden fruit.