Mountain Goat Bighorn Sheep Interactions at Mineral Licks
by Brandon Swanzer
Field Note #13
Left - Bighorn Sheep. Image by Warren A Metcalf Right – Mountain Goat. Image by John Morrison
On an early October trip to Glacier National Park, we arrived at Logan Pass at the top of the famed Going-to-the-Sun road. Not long after arriving and stepping out into the brisk morning air, I noticed a herd of mountain goats on the rocky cliffs nearby. I enjoyed watching them traverse the steep, unforgiving slopes with their tightrope-esque gaits, but I couldn’t help but make another observation. These goats were standing in the same exact spot I had noticed Bighorn Sheep inhabit on an earlier trip to Logan Pass just two months prior. This got me wondering - what happens when these species meet? Do they peacefully coexist? Or is there conflict between the two?
Lucky for me, at the exact moment I was pondering these questions, a research paper by Berger, Biel, and Hayes from Colorado State University was in the process of being published in Frontiers of Evolution and Ecology. The study originated with a simple observation of a mountain goat driving bighorn sheep off of a mineral lick in Montana. This led to them launching a larger investigation in which mountain goat and bighorn sheep interactions were researched in three locations - Caw Ridge in Alberta, Mount Evans in Colorado, and yes - Glacier National Park, right where my curiosity began.
The findings of the study were fascinating to say the least. While there have been examples of a species driving a differing species off of sources of water, food, shade, or minerals, the typical result is the larger species “wins”. However, mountain goats and bighorn sheep are similar in size. This would perhaps lead you to believe that conflicts would be fairly evenly split in deciding which species prevails. The study, on the other hand, found that in 120 interactions between mountain goats and bighorn sheep, over 95% of them ended with the mountain goats winning access to the mineral licks.
Another interesting finding was that 73% of these interactions were won in passive interactions, in which the bighorn sheep fled without the mountain goat having to become aggressive. While the study did not reveal a clear explanation for this overwhelming dominance from the mountain goats, the researchers theorized that this was due to the goats being naturally more aggressive than bighorn sheep. However, more research will need to be conducted to confirm this.
One other question remains - however - why are these interactions happening now? One theory that the study posed is that melting glaciers from climate change coupled with less access to resources at lower elevations due to human development has caused competition for resources in higher elevations to increase. This is because the melting glaciers have introduced new access to mineral licks that were previously restricted. If this theory is fact, we could begin to observe more conflict between these species. However, due to insufficient historical data more research will need to be conducted.
It should also be noted that if climate change is the culprit, there is potential for other sources of conflict to arise. While the core source of conflict was in relation to mineral licks, it is believed that rising temperatures could lead to less snow. Because mountain goats and bighorn sheep both utilize snow for cooling and water, there could be potential conflicts as access to snow becomes more sparse.
Finally, the observations this study has made could lead to a complex problem for wildlife management. While both mountain goats and bighorn sheep are native to Montana and Alberta, only bighorn sheep are native to the third study site in Colorado. In fact, mountain goats were introduced in several areas in which bighorn sheep solely occupied previously, including Colorado, Utah, and Wyoming. If bighorn sheep populations begin to struggle, do we remove the mountain goats that were not originally from there? Or do we find other avenues to allow mountain goats to remain in these areas while also providing enough resources for bighorn sheep to survive? These are questions that we may have to answer in the not so distant future.
Regardless of what happens in the future, I will continue to hike in high altitude regions and respectfully observe both of these species that I find so fascinating. However, as I walk amongst steep mountainous slopes, I will now have a new appreciation for mineral licks and the behavioral ecology at play between goats and sheep. While mountain goats may drive bighorn sheep off of mineral licks 95% of the time, I have no doubt in my mind that either species can drive me off of them 100% of the time.
Sources:
Berger J, Biel M and Hayes FP (2022) Species conflict at Earth’s edges – Contests, Climate, and Coveted Resources. Front. Ecol. Evol. 10:991714. doi: 10.3389/fevo.2022.991714
Nuwer, R. (2022, October 17). Mountain Goats Battle Bighorn Sheep over Climate-Limited Resources. Scientific American.
