Final answer:
An ecologist studying the patterns on the wings of an endangered butterfly species is conducting an observational study to understand how it escapes predators.
Step-by-step explanation:
An ecologist studying the patterns on the wings of an endangered butterfly species to understand how it escapes predators is conducting an observational study. In this type of study, the researcher measures characteristics in a sample but does not manipulate or control variables of interest. By observing the patterns on the wings, the ecologist is collecting data without interfering with the butterfly's natural behaviors. This non-invasive approach allows for a better understanding of how the butterfly species interacts with its environment.