So, what do I think?
Bird shot:
Technical: ISO 100,f/5.6, 1/320 sec., 171mm, auto exposure, auto white balance. Focus is a bit soft, but it is clear thatyou are shooting through wire netting (can be seen in the out-of-focus highlights in the background), so maybe you got the best that could be gotten.
Compositional: Thebird’s eye is centered, and his/her beak is almost against the left side –feels awkward. Positioning the eye closer to the right 1/3 line and giving some space to the left of the beak would have given the bird some “breathing room”. Our eye is immediately drawn to the bird’s eye, then we follow the direction of the head to the left, run into the left wall, and come back looking at the plumage of the bird’s neck, then back to the eye. The space to the right is wasted. The background is relatively neutral and doesn’t compete with the bird. Overall the image could do with a bit more sharpening and contrast.
Butterfly shot:
Technical: ISO 800,f/5.6, 1/250 sec, 194mm, Auto exposure, auto white balance. Focus appears to be just behind the butterfly, as the tail end of the body appears soft ant the antenna are very soft. The edge of the leaf is sharp, butI don’t think that was your target. Shutter speed is appropriate for that focal length and hand-held shooting. You were at the wide-open setting for that lens, and had to boost the ISO to get the right exposure.
Compositional: Thebutterfly is centered, which generally gives a static image. One of the useful techniques to know is to leave some space in front of the animal, so that it is looking into the image. The twigs in the background are somewhat distracting. That is due to it being quite close to the butterfly, and therefore not sufficiently out of focus. To get good out-of-focus background, you need to be closer to the subject, and have more space between the subject and the background.
Tiger shot:
Technical: ISO 1000,f/7.2, 1/400 sec. 250mm Auto exposure,auto white balance. Better would have been 1/320, f/5.6, ISO 400, mainly to get the ISO down. Your shutter speed of 1/400 could be lowered to 1/320 and still be within the “handshake” limit with a 250mm lens. A slightly more open aperture would have also made the background slightly more out-of-focus. Focus on the tiger appears to be good.
Compositional: The cropping to be done depends on the intent of your image. If the focus was to be on the tiger, then the right side can be cropped just to the right of the tiger to eliminate the tree and the concrete at the back. The top of the image could be cropped a little above the tiger’s head. The result would put the tiger at the 1/3 line(more or less) on the right, and give some space to the left for the tiger to “look into”.
If the intent was to show the tiger in artificial confines, then a vantage point a little more to the left would have placed the “artificial” elements closer to the tiger in the image and would have made that link more obvious.
Other comments: The main reason to watermark an image is to protect it from being copied. Do you believe that your images are sufficiently good that you need to protect them that way?