Here's why:
* Hunting patterns: Killer whales are apex predators and their hunting patterns are influenced by the behavior of their prey. Some of their prey species, like salmon, are more active at dawn and dusk.
* Social behavior: Killer whales are highly social animals, and their communication and interactions are also more frequent during the transition between day and night.
* Energetic considerations: The cooler temperatures and lower light levels during dawn and dusk may help killer whales conserve energy.
However, it's important to note that killer whales can be active at any time of day or night, depending on the specific circumstances and their prey availability.