Which of the following is an example of a causal question?

A causal question seeks to understand the relationship between variables, particularly how one factor influences or causes changes in another. In this context, the statement regarding factors that influence migration patterns in birds directly addresses the cause-and-effect relationship by asking what elements might lead to changes in these patterns. Investigating migration involves looking at various influences such as climate, food availability, or habitat changes, which are all potential causal factors.

The other choices do not focus on cause-and-effect relationships. For instance, asking how many eggs a female guppy lays is a question about a specific behavior or characteristic rather than its underlying causes. Similarly, questioning whether male fish exhibit mating displays is more about observing the occurrence of a behavior rather than exploring what causes that behavior. Lastly, asking about the appearance of a species' nest describes a trait or characteristic rather than investigating the reasons behind its construction. Thus, the question about what factors influence migration patterns is distinctly causal, as it seeks to uncover the reasons behind a specific biological phenomenon.