American ermines turn brown in summer and pure white in winter except for a black-tipped tail that stays constant year-round, a seasonal disguise that works well in Oregon’s snowier country. Records cluster around Malheur National Wildlife Refuge’s high desert wetlands and Klamath Marsh National Wildlife Refuge, both places where marshy edges hold the small rodents this weasel hunts.
Records climb through late spring and peak in July, with a smaller September rise, likely tracking the stretch when this year’s young are old enough to hunt and be spotted alongside a parent. Every one of Oregon’s 69 records relies on iNaturalist rather than GBIF specimen data, unusual for such a small, secretive predator and a sign that most sightings here are genuine photographed encounters rather than trapping records.
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