Which of the following is NOT one of the 4 basic characteristics used for animal identification?

The correct answer is that the color of the eyes is not considered one of the four basic characteristics used for animal identification. The primary characteristics typically include markings, sounds, and group behavior, all of which are more relevant and reliable for identifying animals in various contexts, such as hunting or wildlife observation.

Markings are unique patterns or features on an animal's fur or skin that can help distinguish one individual from another. Sounds produced by an animal can also serve as significant identifying traits, particularly for birds and vocal mammals. Group behavior refers to how animals interact within their species, which can provide clues about their identity and social structures.

In contrast, eye color is generally less variable within many species and does not play a substantial role in identification, making it less useful compared to the other characteristics mentioned. Thus, while eye color can be an interesting feature, it does not serve as a fundamental characteristic for animal identification, which is why it is the correct answer here.