1 Tortoise's highlights are blown and one leg cut off. I like that you got down to his (her?) level and your background is nice. What is that on it's back?
2 The building seems underexposed, but nice barn. The sky is uninteresting and possibly blown. I'd say a closer crop and better lighting would make this a nice shot. Are those power lines? I'd probably clone those out too - very distracting. The location has a lot of potential though.
3 I think this is the strongest of the lot with the different blocks of colors. Would have loved the animal (goat?) to not be behind the post.
4 What is that? Looks creepy. Try adding contrast...I think it's too gray. Composition-wise it looks good.