The Ninja devised an ingenious method of telling time by using a cat's eyes. Since a cat has such sensitive eyes, they adjust frequently as the sun passes through the sky. This picture illustrates how the Ninja used this knowledge to approximate time:
The Ninja, like sailors, used the stars to navigate at night but they also discovered 2 other ways of determining direction. One is through the use of a tree stump. If the Ninja came across the stump of a tree, he simply looked at the growth rings to tell which direction was North. The rings become narrower and closer together as they approach North and wider and further apart as they approach South.
Another, more accurate way, of determining direction was by the use of the sun and 3 sticks. This method accurately determines True North. The Ninja found a fairly clear area that wasn't overgrow with trees or bushes, etc. then he found a stick that was about a foot long and 2 twigs whose length didn't matter. The Ninja drove the foot long stick into the ground and observed the shadow cast by it and then placed one of the twigs on the ground, at the end of the shadow. He then waited about 15 minutes for the shadow to move and placed the other twig at the end of the shadow's new location. The Ninja then placed his right foot on the first twig and his second foot on the second twig and the Ninja was now facing True North.
Even the Ninja had to rest from time to time and one of the best places to hide was in the tops of the trees. Since Ninja wore an exceptionally long sash, he was able to climb to the thick, upper branches of a tree and then tie his sash from limb to limb in a "spider web" type pattern, creating a serviceable hammock to rest in and to watch for approaching enemies.
Since the Ninja had to survive in nature, they became trained naturalists capable of distinguishing edible, medicinal and poisonous plants, trapping, preparing and cooking animals, building shelter, finding water, and making fire.
A few methods of finding water were by studying the insects in an area. For example, if there was a high concentration of ants or crickets, he knew there was water nearby. Another way of finding water was by recognizing the kinds of plants that live near water. If the Ninja found any of those plants, he knew water was near.
Box of Crickets
Another tool used by the ninja was a simple box of crickets. They
would carry with them a small box of crickets to cover up any small
sounds made by the ninja as he quietly advances on his target. The
noise made by the crickets was not uncommon, so they samurai thought
nothing of hearing them.