Wildlife Wednesday — This Year’s Elk Rut
By Any Ames
If it seems like the elk rut has been subdued this year, it is not your imagination. Denver recorded its hottest September on record this year and that heat extended to the Estes Valley. Elk have a number of physical and behavioral adaptations to deal with the heat. On the physical side, elk sweat to cool by evaporation and pant to expel hot air. Behaviorally, they are masters of their environment. They use microclimates to their fullest extent. Elk may move up in elevation to find cooler air, head to the trees for shade, bed down in a damp meadow, or even take a dip in a lake or river. The most important adaptation, however, is to shift and reduce activity. Elk tend to be lethargic in the heat and shift activity until temperatures cool off late in the day and through the night. All this means less time for breeding. Female elk are in estrous for about 24 hours. If they do not mate during this period they will repeat the cycle every 3 weeks. It will be interesting to see if the rut lasts longer than usual or if it ends as is typical in mid October. I guess we will find out the results in the calving season next spring.
A Bull elk finding refuge from the heat and bugs on a hot summer day. If the cold water is not enough, a quick shake upon exit enhances evaporative cooling. Elk have a a couple of physical adaptations that help keep them cool, too. Their summer coat lacks the thick undercoat of winter while thin guard hairs allow sweat to evaporate. The growing antlers of males is covered with a velvety skin. That skin is full of blood vessels which further aids in cooling due to the increased circulation and surface area.
Elk are masters at utilizing niches and microclimates in their environment. Tall grass provides a good meal while also indicating a cool, moist spot to bed down. This makes a good mid-morning refuge before heading into the woods for the warmest parts of the day.
After a long night of bugling a bull elk rests with his harem in the shade. The most important adaptation to deal with the heat is to reduce activity. When activity is necessary, it is done during the coolest time of the day (or night in this case).
While elk do sweat to enhance evaporative cooling, panting can help expel warm air from the body. Sweating and panting are a methods of last resort due to the high water loss and risk of hypo- or hyperthermia.