Portrait photography is not just about people, it can apply to wildlife subjects as well. Proper technique and subject knowledge is equally important in capturing great images of wild animals. First and foremost, know your subject: its behavior, fright/flight distance, how dangerous it is and when to back off if you are disturbing the animal…
When photographing small subjects like butterflies, you need to adjust your aperture settings for good macro images. Using the depth-of-field preview button will help you see what elements of the photo you are focusing on, so you can adjust your settings accordingly.