Montana Field Guide

Small. Length 10-12cm, mass 5.4-10.5 g. Adult male in breeding plumage has upperparts uniformly yellowish olive green; forehead supercilium, lores and entire underparts lemon yellow, and crown glossy black forming a prominent cap on top of head. Black eye stands out on yellow face. Breeding adult female is similar but duller overall with a crown that is hightly variable - may be entirely olive, black with olive mottling, black with olive tips or uniformly black. (Ammon and Gilbert. The Birds of North America, No. 478, 1999).

Bozeman area normal migration periods: May 20 - Jun 5 and Aug 10 - Sep 20.

Breeding territories are usually located in riparian habitat or wet meadows with extensive deciduous shrub thickets. Likes edges of beaver ponds, lakes, bogs and overgrown clear-cuts of montane and boreal zones. (Ammon and Gilbert 1999).

Bees, flies, mayflies, spiders, beetles and caterpillars. Occasionally eats berries. (Ammon and Gilbert 1999).

One brood per season is normal for high-elevation Rocky Mountains. Course nest reflects available vegetation. Clutch size is 2 to 7 eggs with 4 eggs being most common. (Ammon and Gilbert 1999). Nest with eggs on Jun 6. Egg records are probably similar to those in Colorado -- Jun 1 - Jul 3.