What term describes an organism that is most active during dawn or twilight?

The term that describes an organism that is most active during dawn or twilight is "crepuscular." This term specifically refers to animals that are primarily active during the hours around sunrise and sunset. Crepuscular behavior is an adaptation that often helps animals avoid predators and take advantage of cooler temperatures when compared to the heat of the day.

In contrast, diurnal refers to animals that are active during the day, while nocturnal describes those that are active at night. Ruminant does not pertain to activity patterns, but rather describes a category of animals that digest food in a specialized stomach. Understanding these distinctions is crucial for wildlife management and observation, as it helps in determining the best practices for monitoring and controlling wildlife populations effectively.