Breeding frenzy: If you love wildlife, let the big animals have their annual fall mating season

Bighorn rams often curl their upper lips and take deep breaths. The air carries the sheep’s pheromones to the organ in the roof of the mouth, which informs the animal about the receptiveness of the female.
Rick Spitzer/Special to the Diary

What is rut ​​and how do people affect rut?

The rut is probably the most vital event in a species’ annual life cycle. The rut is the mating season for many large mammals, usually in the fall. This generally involves migration through wildlife corridors to a specific rutting area.

The most popular rut in our region is related to elk. Whirling and hunting activities are something that thousands of people enjoy every year. Selections that disrupt human migration corridors or habitats where destruction occurs can lead to population declines or even the complete extinction of this herd.



Many animals have a mating cycle. For wildlife watchers, the obvious animals are the big tusks in the state. This includes mule deer, white-tailed deer, bighorn sheep, moose, rocky mountain goats, pronghorns, and bison. The only animal in Eagle County that does not live in the wild is the bison.

Why is there a special time for these animals to start moulting? The period of gestation (pregnancy) should correspond to seasonal conditions. Females spawn in the fall when they imbibe, and in the spring when it’s warmer, the weather is less severe, and the plants turn green. These are all factors needed to help vulnerable newborns survive.

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Bighorn rams will mate with lots of ewes during the wet season.
Rick Spitzer/Special to the Diary

The purpose of animals in nature is to produce future generations. The spawning season varies by species in terms of length and duration. Timing is based on photoperiod (amount of daylight each day). As darkness increases, a hormone called melatonin, produced by the pineal gland in the brain, begins to increase, which causes estrus in females. In men, melatonin increases testosterone levels. The behavioral and physiological changes seen during the rut are triggered by these hormones, leading to the behavior we see during the breeding season.

For men, melatonin causes an increase in testosterone, which leads to major changes in aggression, interest in women, and significant physiological changes. The aggressive nature of males can be dangerous for hikers and cyclists.

Bull moose really bulk up before the rut. They produce antlers up to 6 feet long and weighing up to 40 pounds.
Rick Spitzer/Special to the Diary

Moose can be extremely dangerous. A walker with his dog is even more at risk. Moose see all dogs as prey and will attack aggressively. Moose react to all dogs in the same way as wolves, the main predator in the wild. They try to crush the dog with their nails.

CPW advises people to follow these tips to stay safe around moose:



  • Keep a safe distance between you and the animal.
  • Approach them slowly rather than directly. Back off if they show signs of aggression, such as standing up, licking their noses, shaking their heads, and rolling their eyes and ears.
  • Keep pets away and leash dogs.
  • If the moose shows aggressive behavior or starts to charge, run as fast as you can and try to put a large object such as a rock, car or tree between the moose and the moose.

Road closures may seem like a good option to prevent problems with moose. Because of the wide range of moose in Colorado, this would be impossible.

Deer, moose and elk have evolved antlers and behavior to appear more attractive to females during the moose. Their glandular secretions, absorption in their own urine, and attacks on bushes and trees also distinguish them from females. Battles using their horns are also common. During these demonstrations, the bull cow is also bellowed (whistle-like sound).

The bull bull collects the cow’s feathers and protects them from all the other bulls. They shed their horns in the spring and grow new ones every year.
Rick Spitzer/Special to the Diary

Bighorn sheep rams will often snort loudly. When challenged by other males, they stand up next to them and kick the other animal. They then pull back, face each other 10 feet or more, and charge head-on at 35 miles per hour. Bighorn sheep can do this hundreds of times in an afternoon.

The horns of bighorns remain on the animal for life. They show battle wear. This ram is perhaps in its ninth year.
Rick Spitzer/Special to the Diary

Rocky mountain goats have a threat display but rarely fight. Punctured wounds are sometimes observed in men.

Pronghorn males will often grunt and defend their harems and territories by pushing and head-to-head fighting.

Male ibex, called billies, usually live alone or with one or two male goats. They join the females, called nannies, in the autumn humidity. Billies keep their horns for life.
Rick Spitzer/Special to the Diary

It is often interesting to watch the young males of any of these species. They hang around the edges of another male’s territory, waiting for a chance to mate with a female. While larger males are busy showing their dominance, smaller males often get the chance to mate.

All these species communicate in three ways during the rut. Visually, they show all kinds of things. They express themselves vocally and have scent-based communication. They produce secretions that contain pheromones and other compounds. These secretions are often rubbed on trees, branches and grass to communicate with other animals. Legumes have seven external scent glands. One of these glands is the gland in front of the eye, which expands dramatically when wet.

During the rut, the preorbital glands in front of the eyes produce secretions containing pheromones. Amphibians often store these secretions on trees, branches and grass.
Rick Spitzer/Special to the Diary

Rut requires a large amount of energy from men. A lot of energy was spent building the horns of legged animals. Since this was in the fall, men may have used up a lot of energy and bodily resources. They go into winter and have a hard time surviving.

One of the challenges for many species is that these animals have a summer range and in the fall move to winter ranges, which are important for breeding and feeding. In Eagle County, several of the corridors used by these animals and the wintering area itself are fenced off. Interstate fencing can make a big difference in reducing vehicle-animal collisions, but fencing can cause population declines because animals cannot use all of their historic range. People who have lived in the county for a long time often comment on the fact that animals in an area are no longer visible.

In several parts of the county, large summer and winter areas may be completely excluded from animal access due to residential and commercial development. Therefore, these animals may experience a reduction in reproductive success during the rut. Some people say that wildlife will find other areas. Research shows that this is often not the case. Those animals die.

Success during the rut is important for raising young to perpetuate the species. They give birth in the spring when it’s warmer, the weather is less harsh, and the plants are turning green.
Rick Spitzer/Special to the Diary

Another problem during a rut is the effect of rest. Hiking, biking, ATV riding, snowmobiling, and the desire to see this display in nature bring people to areas that can be affected by humidity. Noise, dogs and close encounters will be distracting and reduce breeding success during the wet season. If an area, trail or road is marked as closed, do not enter.

Rocky Mountain National Park now closes several areas to all use during elk drives. In the 50s and 60s, a trip to the eastern side of Rocky Mountain National Park to see the ruins was a quiet and exciting experience. There were few people there. It was like throwing tails. Lots of food including lawn chairs, Coleman stoves and S’mores were consumed while waiting for the elk herds to show up.

You can easily stop almost anywhere on the road to watch and hear hundreds of elk in their emerging herds. Over time, as the number of people increased, visitors approached the moose and endangered themselves by disturbing the path. From September 1 to October 31, park officials close the park between 5:00 p.m. and 10:00 a.m. and prohibit hiking or horseback riding on designated roads or designated trails.

Male pronghorns have horns, but they are shed and regrown every year. They are the fastest land mammals in the Western Hemisphere.
Rick Spitzer/Special to the Diary

Another growing problem is the use of drones in these areas. Unfamiliar noise can cause animals to run away with extra energy. In many places, the use of drones is prohibited so as not to disturb wildlife. Fines and loss of the drone can be punishment for their illegal use.

Just like the problem with bears in garbage cans, human behavior and the choices they make are problems. The bottom line is that if we want to continue to enjoy wildlife, we must make choices that do not disrupt the natural cycles in this environment. As more people move into this area, our choices for building, zoning and recreation must be made with consideration of how it will affect all wildlife. Wild animals cannot vote or sign petitions. We can. Get involved!

Rick Spitzer is a renowned wildlife photographer and longtime Wildridge local. The Eagle County Community Wildlife Roundtable is a partnership with the White River National Forest, Colorado Parks and Wildlife, Bureau of Land Management, local government agencies, community members and citizen scientists. The purpose of the Eagle County Community Wildlife Roundtable is to bring together a group of diverse stakeholders in the valley to understand and address issues facing wildlife populations.

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