I hope we didn’t learn this from the Japanese during ww2

My uncle had 2 Newfoundland’s when I was a kid. We used to take a family trip to northern Michigan looking for mushrooms every Mother’s Day weekend and he brought his dogs. As you know they listen pretty well so he’d let them wander off leash. One outing he’d gave a whistle for them and a short distance from us we heard a scream and a lady yell “bears”.