Stars can be used for navigation and a compass will provide an accurate assessment of north/south direction, but you can also use nature to determine the general direction in a pinch. Moss, puddles, snow melt patterns, rings in a tree stump, even animal behavior can be used to help you determine your north and south direction of travel.
Using moss and puddles of water to determine direction
Using moss on a tree to find direction can work in some cases but it not always accurate – sometimes moss grows completely around the tree trunk. Moss prefers moisture and shade and in the right circumstances, it can be an indicator of direction. In the Northern Hemisphere, moss growth will be more lush on the north-facing side of the tree while in the Southern Hemisphere, moss growth will be heavier on the southern side of the tree.
Similarly, puddles of water will lay longer in areas that do not receive as much sunlight. In the Northern Hemisphere, puddles will typically stay longer on the northern side of trees or other objects, In the Southern Hemisphere, puddles will more likely lay on the southern side of an object.
Using tree stumps to determine north/south direction
Felled trees can be used as directional indicators. In the Northern Hemisphere, the growth rings in a trees trunk tend to be more widely spaced on the southern side of the tree – the side that gains more sunlight. It works vice versa in the Southern Hemisphere with wider tree rings on the northern side of the tree.
Using vegetation, moisture, and wind patterns to determine direction
Recognizing the differences between vegetation and moisture patterns on north- and south-facing slopes can aid in determining direction. In the Northern Hemisphere, north-facing slopes receive less sun than south-facing slopes and are therefore cooler and damper. In the summer, north-facing slopes retain patches of snow. In the winter, trees and open areas on south-facing slopes and the southern side of boulders and large rocks are the first to lose their snow. The ground snowpack is also shallower due to the warming effects of the sun. In the Southern Hemisphere, all of these effects will be the opposite.
If you know the prevailing wind direction in your area, you can use wind or wind related clues to determine direction. For instance, if the wind typically blows from the south in your area, look for ponds or stagnant water and notice which side the debris on the water’s surface has settled on. It will settle on the opposite side of the wind direction.
Using animal behavior to identify north/south direction
Scientists have determined that many animals have the ability to sense the earth’s magnetic field and thus determine direction – a fact that seemingly went unnoticed by hunters for thousands of years. Cows often sit right before it rains and will group together before a blizzard or storm. Similarly, cows also tend to face in the same direction when they graze. Only recently have scientists discovered that cows around the entire planet tend to face in the same direction when they graze. Although it is unclear why they behave in this manner, it has been proven that they tend to face in a north-south direction. Only around the equator, where magnetic fields are not as strong, do they face in a slightly north-eastern or south-western direction. Other animal herds, including deer, are believed to follow the same behavior. Interestingly, satellite photos show that animals break this behavior and graze in totally random directions when under or near power lines.
Another animal behavior that could help determine direction is the spinning movement a dog makes before laying down or using the bathroom. Especially in outdoor environments, a dog will typically conclude the spinning movement when the detect the northerly direction.