Picture 1 could use a slightly closer crop as the yawn is so important to the subject matter. Picture 2 needs a major crop as the Tiger is just too small and not that visible, and since he's in the shadows, you need to increase the exposure. Pic 3 could use a slight crop as well. Out of the 3 pictures, pic #1 is my favorite. For zoo pictures you did a nice job of giving us a sense of openess with no visible sense of an enclosure.