There's bunches of reasons to observe the evidence animals leave behind - in the woods or even around your suburban home. The main reason is just for the sheer joy of seeing how awesome and intelligent nature really is, which cultivates a great respect for the earth we live on (observing is my most favorite thing to do), but then there are things like half your flock of chickens is wiped out in a night and you need to know what animal you are dealing with in order to secure your hens properly (raccoon, fox, owl, hawk, coyote...). An even more basic reason to follow the behavior of animals is for survivalist reasons, and I don't mean being a survivalist just for fun or in fear of apocalyptic doom but I mean the economy being so bad that it becomes more apparent you are so poor you will need to feed yourself off the land. In the end, growing and trapping your own food is the most ecological way to live anyway.
Animal tracks (like the deer tracks above) will reveal the paths the animals use on a regular basis. While I don't want to eat a deer (even in a bad economy) I do love to see them doing their thing - it makes me forget about any worry I could have in life. In the picture below are some wild rose bush briers, which have a little cave type arch and shelter quality. Since I walk this path regularly, I know that this sprucing up of the bush is something that just happened. It takes a lot of patience to wait for animals to come by, but if you really want to observe them, you have to find a hiding spot close to some evidence and wait for the magic to happen.
These giant holes below are made by one of the biggest woodpeckers in existence! I have seen them only twice in my life (cause they are too crafty) , it's like spotting an eagle though cause they are so HUGE. They have a giant red head and hammer so hard on the wood it will rock your house. (I found one hammering away on my house siding once). They do this in order to find ants living inside dead trees. Pretty neat!
Where a dead tree falls down, a new path is created. This tree below created a deer super highway - when I say there were too many tracks to even decifer I don't exaggerate! It looked like NYC 5th avenue traffic...nature style.
Lastly is poop, or better known to tracking enthusiasts as "scat". Poop seems pretty easy to identify, but I am not quite sure about this one pictured below. I looked up the categories for dog, cat, deer, rabbit and rodent and it didn't quite fit in any of them. It was out in a open field near a tomato garden and apple trees, which attracts alot of critters all shapes and sizes. There were a few other scat bits near this one too, smaller in size.
Hey Tom Brown Jr., what kinda poop is this?