The Rocky Mountain autumn is defined in many ways-frost on morning grass, color creeping into shimmering aspen leaves, ice rimming mountain ponds. There are sights and smells to a Yellowstone autumn, elements that, if you've visited here many times, become as familiar as old friends. But nothing etches the lens through which we see fall as much as the rut of the elk, Cervus alaphus. The reason for this is almost entirely auditory.
The Sound of a Bull Elk in Autumn
If you've never heard the bugle of the bull elk during the fall rutting period, you are in for an experience that is at once thrilling and haunting. The sound of a bull elk bugling is something that draws many visitors to Yellowstone each autumn, for it is an experience as memorable as anything you are likely to have in the park. In most cases, the bugle starts low and throaty, rising to a high whistle, then dropping to a grunt or a series of grunts. It's a sound that is difficult for the human alphabet to imitate, a guttural bellow, a shrill pitch, and a hollow grunting. A-a-a-a-a-a-a-a-eeeeeeeeeeeeee-oh. Ee-uh. Ee-uh. Ee-uh. It's an odd combination that, like the buzz of your first rattlesnake, you'll never forget.
In many cases, the bugle is interpreted as a challenge from one bull elk to another. This is commonly the result of a dominant bull that may have a harem of cows that he is carefully guarding. A challenger steps into the meadow and bellows a challenge. In return, the herd bull gives voice to his answer, which is often deeper and clearer than the challenger, a voice of maturity and dominance. In many cases, the challenger is run off by the herd bull, while a less mature bull than even the challenger, perhaps a bull as young as two, slips in and breeds a cow.
Elk Rut Season Peaks in September
Each fall, starting as early as August 15 some years, elk enter their breeding season, or rut. The rut continues for about a month in length, and that month is typically September, with the middle of the month the height of the rut. Sometimes, the rut extends into October and bugling bull elk have been heard giving voice as late as mid-October. For elk, the month of September is an age-old phenomena and one that quickens the human heart. Along the Madison River, especially, September is a month when people can see the mating season of elk in full swing. Here, some of the top photographers in the world gather every year to take picture after picture of mature bull elk and their harems. Many of the photographs that are seen in magazines are taken along the Madison during September.
Bull Elk Behavior During Rut
Typically at this time of year, one big mature bull will hold a herd of up to thirty or more cow elk, half of which are in prime breeding condition. In this herd, there might be an occasional yearling bull, or "spike." There may even be an occasional hanger-on, a young bull that is attracted to the herd, but subordinate to the big bull. This herding pattern is not seen at other times of the year; in the summer, cows, calves and yearlings usually run in large herds, while bulls are either solitary, or run in pairs or trios. In winter, the separation is even more evident as bulls run in large bands, called bachelor groups, and the cows, calves and immature bulls run in herds that can number several hundred or more. Usually, the bulls at this time of the year are in more rugged, less accessible country, while the cows, calves and younger animals will use country that is closer to roads and human activity.
But it is the fall, with the music of elk all around, that is the most enthralling of all times. Bull elk during the rut can bugle often, even in the middle of the day. The intensity of the rut is often hallmarked by the frequency of the bugling. Bugling can continue right on through the night, regardless of whether there's a moon or not. Some bulls, exhausted from hours of herding and breeding cows, and occasionally sparring with other bulls, will lazily bugle while lying down.
It's a Hard Time for Bull Elk
For the bull elk in charge of the herd, the rut is a tough time. Because the bull's attention is so focused on his ladies, he often doesn't take the time to eat. Bulls lose weight during this time of year, while other animals, including cow elk, are gaining weight in this time of harvest and fattening. Bull elk in the rut will dig out wallows in marshy grass, places where mud and water pool. There, they will thrash about to cool down, to chill the intensity of the rut. At the edge of the wallow, it's not unusual to see small, hapless trees thrashed to bits, or places where the bull has run his antlers into the mud and then tossed chunks of sod high into the air. The rutting bull elk is at once somewhat vulgar (he frequently urinates upon himself) and majestic.
A cow elk reaches breeding age during the third breeding season after it was born-at about two and a half years old. Young bull elk apparently become sexually active a little earlier, at just over a year in age, but unless they are very fortunate and are able to slip past the watchful eye of the harem master, they generally don't have a chance to breed until they are more mature, tougher, and better at wooing and herding cows.
Battles among bull elk in the throes of the rut are not uncommon. Usually, the battles are minor, with the clash of antler on antler, and the subordinate bull runs off into the timber. But sometimes, the fights are more intense, and result in injury or death. Bull elk can weigh up to one thousand pounds and two bulls this size can cause a lot of damage to each other as they throw themselves antler to antler. It's a shoving match with deadly head gear, a tussle that can end up in bloody damage.
As the rut draws to a close, the bulls will move back into a solitary existence to re-charge and re-fuel. Because the rut is in September and the worst of the Rocky Mountain winter doesn't hit until later, bulls often have a chance to rebuild fat reserves after the rut. But occasionally, winter comes early to the Rockies and during these times, bull elk-weakened from the rut-succumb to the elements, or are more easily taken by predators like wolves.
Springtime Elk Calves
In the spring, cow elk begin to separate from the herd in search of a quiet place for birthing around May 15, some eight to eight and a half months after they were bred. The cow almost always has a single calf, but there are reports of the rare set of twins. Twins are much more common in mule deer and antelope than in elk.
Calf elk are at first very wobbly and unsure of their footing, but they quickly grow into their legs. As with all animals that are preyed upon by predators, elk depend upon their ability to run to avoid becoming dinner. Elk calves, while very vulnerable and defenseless at first, become more and more adept at avoiding danger as they grow up. They are excellent at using cover like sagebrush and aspen groves to avoid detection and predators that aren't aware of their presence have been known to walk right past a hidden, stationary calf.
Thus begins the cycle that starts all over again each September with the moving song of the Yellowstone-the elk.