GLACIER NATIONAL PARK, Montana – Ever summer a great migration takes place in Glacier National Park. Army cutworm moths move en masse from the plains of Montana to the high alpine peaks of the national park. This migration barely affects the human visitors of the park, but it does create a massive feeding opportunity for the area’s grizzly bears. These moths, as small as they might be, have managed earned themselves the nickname “bear butter”. Students and researchers dug around the rocks of the high alpine to collect these moths, with the goal of studying their importance to the regions bear population.
These army cutworm moths act as a pretty major food resource for grizzly bears in Glacier National Park, despite being just around ~¾ inch long. As these moths spend their summers in the rocky mountain slopes, they manage to build one of the largest lipid reserves of all animals. 70% of their body weight can end up being in fat, or lipids, as they feed in the mountains. For bears, this means a calorie dense snack, much more dense than elk, goats, and other animals found inside the park.
For grizzly bears prepping for the winter, life is all about calories. The harder they have to work to capture a meal, the more calories they burn doing so, and the less weight gained from the meal. These moths require little work to capture and kill, with the grizzlies essentially sucking them out of the ground. And with less human activity high up in the mountains, it’s an easier and less stressful hunt.
The presence of these feeding sights means a grizzly bear encounter is still very possible in the barren high alpine, as likely as it might seem. So if you plan on hiking, you should always be prepared for such a possibility. This means carrying bear spray anywhere in bear territory, and understanding how to keep yourself, and others, safe in an encounter.
Glacier National Park on Bear Encounters:
If you encounter a bear inside the minimum recommended safe distance (100 yards; 91 m), you can decrease your risk by following these guidelines:
- If a bear or other animal is moving in your direction on a trail, get out of its way and let it pass.
- If you can move away, do so. If moving away appears to agitate the bear, stop. In general, bears show agitation by swaying their heads, huffing, and clacking their teeth. Lowered head and laid-back ears also indicate aggression. Bears may stand on their hind legs or approach to get a better view, but these actions are not necessarily signs of aggression. The bear may not have identified you as a person and may be unable to smell or hear you from a distance. Help the bear recognize you as a friendly human.
- Talk quietly.
- Do not run! Back away slowly. Stop if it seems to agitate the bear.
- Use your peripheral vision. Bears may interpret direct eye contact as threatening.
- Continue to move away as the situation allows.
- If a bear appears intent on approaching you, your group, or your campsite in a non-defensive manner (not showing signs of agitation), gather your group together, make noise, and try to discourage the bear from further approaching. Prepare to deploy your bear spray. If you are preparing or consuming food, secure it. DO NOT LET THE BEAR GET YOUR FOOD!
- If a bear approaches in a defensive manner (appears agitated and/or charges), stop. Do not run. Talk quietly to the bear. Prepare to deploy your bear spray. If contact appears imminent and you do not have bear spray, protect your chest and abdomen by falling to the ground on your stomach, clasp your hands around the back of your neck, and leave your pack on for protection. If the bear attempts to roll you over, try to stay on your stomach. If the attack is defensive, the bear will leave once it recognizes you are not a threat. If the attack is prolonged, FIGHT BACK!