What essential item should hunters carry to signal for help in case of an emergency?

Hunters should carry a whistle as an essential item to signal for help in case of an emergency because it is an effective and reliable means of communication. Sound can travel much farther than the human voice, especially in remote areas where environmental noise may be minimal. A whistle requires little energy to use, making it suitable for prolonged signaling, unlike a flashlight or other items that may require batteries or power. Additionally, it can be used repeatedly and does not depend on visibility conditions, such as light levels needing a flashlight or the visibility needed for using a mirror. Carrying a whistle can significantly enhance safety by increasing the chances of being heard by rescuers in situations where help is needed.