026-07-14 ワシントン州立大学（WSU）
An army cutworm moth flies in Glacier National Park. The moths are a critical food source for grizzly bears, and a three‑year WSU project has mapped the high-mountain habitat where bears forage for the insects (photo by Steven Gnam).
＜関連情報＞
- https://news.wsu.edu/press-release/2026/07/14/amazing-moths-study-pinpoints-insect-habitat-that-draws-grizzlies-to-glacier-peaks/
- https://www.sciencedirect.com/science/article/pii/S000632072600203X
高山性昆虫の基礎となる生物の大規模モデル：ハイイログマの生態と保全への示唆 Broad-scale models of a foundational alpine insect: Implications for grizzly bear ecology and conservation
Erik Peterson, John S. Waller, Don White, Jr., James R. Pierce, Daniel H. Thornton
Biological Conservation Available online: 19 May 2026
DOI:https://doi.org/10.1016/j.biocon.2026.111892
Highlights
- Army cutworm moth (ACM) occurrence is strongly predicted by talus characteristics.
- ACM are confined to isolated talus slopes in mountain environments.
- ACM occurrence was the most important predictor of grizzly bear foraging suitability.
- ACM may be the nexus of a larger alpine food web that has not been well described.
- Conserving ACM aggregations would benefit grizzly bears and the other species that consume this resource.
Abstract
Alpine regions provide temporary habitats for many species and support complex food webs. These ecosystems are poorly described and threatened by anthropogenic stressors. The army cutworm moth (ACM) migrates great distances to aggregate in talus slopes of the Rocky Mountains during summer months. Their high energy content is attractive to grizzly bears, which ascend mountains to consume them. From 2019 to 2021, We implemented two survey techniques to elucidate grizzly bear-ACM interactions across 40 peaks in Glacier National Park, Montana. We hypothesized A) ACM occurrence would be positively associated with cool, wet, air-filled talus environments located near nectar resources, and B) grizzly bear foraging would be guided by ACM occurrence. We used field surveys of talus to create models of ACM occurrence and executed helicopter surveys of these slopes to create models of grizzly bear foraging. We determined ACM occurrence was primarily influenced by the physical characteristics of talus that provided stable, cool microclimates. These environments are rare, with ACM occurrence confined to 0.3% of Glacier. We also determined that ACM occurrence was the most influential predictor of grizzly bear foraging. Our models can help park managers develop access management strategies to limit recreational impacts on moth-foraging grizzlies. Given the importance of talus characteristics for ACM occurrence, finer-level talus characterization is needed for this foundational alpine insect, which is consumed by a variety of other species, in addition to grizzlies. Further insights into the less conspicuous species that consume this energy-rich food resource may illuminate the broader trophic significance of ACM.
