Seasonal distribution and aerial surveys of mountain goats in Mount Rainier, North Cascades, and Olympic National Parks, Washington

Mountain goats (Oreamnos americanus) in Olympic, North Cascades, and Mount Rainier National Parks exhibit seasonal altitudinal movements, with winter ranges at lower elevations (817–1,787 meters) shifting to higher summer ranges (1,312–2,061 meters). GPS-collar data revealed that goats transition between these ranges within a narrow window (June 11–19 for ascent, October 26–November 9 for descent), with home range variability from 0.7 to 37.0 km depending on season and sex. Aerial survey detection probabilities varied significantly across parks (0.69 in North Cascades, 0.76 in Olympic, and 0.87 in Mount Rainier), influenced by habitat openness and group size. While surveys in Mount Rainier reliably captured goat presence, Olympic and North Cascades required adjustments to sampling frames to minimize biases. Expanding survey coverage by lowering altitude thresholds could improve population estimation accuracy.

Jenkins, K., Beirne, K., Happe, P., Hoffman, R., Rice, C., & Schaberl, J. (2011). Seasonal distribution and aerial surveys of mountain goats in Mount Rainier, North Cascades, and Olympic National Parks, Washington. Open-File Report. https://doi.org/10.3133/ofr20111107