The first one's not a bad shot, but it looks like focus is just in front of the eye, generally for live subjects you want the eye in sharp focus. Outside of that, the framing and exposure look good.
The second one is a bit too cluttered for me, there are too many choices for the "subject." The post on the right doesn't add to the composition, and the background isn't blurred enough- I'd have tried to go with a narrower framing and a shallower depth of field. I'd also have tried to find a composition that leads the eye into the frame, this is just too much of a jumble.
The third one needs lighting. The human eye is drawn to the brighter spots in a picture, and in this case, the subject is in the darkest corner and dark itself, while our eyes are drawn to the background, where there's nothing of interest. I'm also not sure the empty space on the right helps the composition any, but without light on the subject it's difficult to tell.
The last one is too centered and too cluttered to work for me. The path doesn't work as a subject because of all the debris scattered about, and the leading lines happily lead our eyes into the center of the frame, but once they get there, there's nothing to focus on. Also, the bright spot on the left is distracting, I'd have framed so it wasn't there.
Paul