Recently split from GCTH. Breeds in stunted spruce on highest mountain tops. ID: Recalls HETH: small and fat with tail often cocked. Rufous in tail and bases to primary coverts/primaries, but always much colder tones and grayer ear coverts. From GCTH by size, shape, rufous tones, subtly browner upperparts and less contrast between ear coverts and nape. NL race of GCTH is a problem! Song similar to GCTH, slightly more even-toned with a stronger ending. Call similar but averages higher-pitched. All differences subtle.