Here are a Red deer hind (female) and hart (male) on the left, with a Wapiti bull (male) on the right. Both males are giving off a rutting call. Wapiti are often described as the North American equivalent of our European red deer. Though they are indeed taxonomically very close, there is an interesting difference in their rutting calls.
Male Wapiti or Elk ‘bugle’, giving off a high pitched yelp that may carry for miles, attracting potential mates. Red deer on the other hand give something more akin to a roar, not only used to attract mates but also to keep his harem together and warn off potential competitors. These different calls have likely originated as adaptation to the species’ respective environments: across the open grasslands that Wapiti inhabit a high pitched call can carry for miles, whereas in the dense forest a Red deer would call home a low, deep sound carries furthest.