Generally shy and elusive and often difficult to detect. A small wood-warbler, 10 to 15 cm. Green above, yellow below, with gray hood. White eye crescents, 1 above and below each eye, present in all plumages. Immatures have yellow underparts, olive-green upperparts and eye crescents, brown-gray (not gray) hood; throat tends to be grayish white (Pitocchelli 1995).
For a comprehensive review of the conservation status, habitat use, and ecology of this and other Montana bird species, please see Marks et al. 2016, Birds of Montana.
Western Hemisphere Range
In Bozeman area, normal migration periods are May 25 to June 5 and August 20.
Commonly found in riparian habitat and clearcuts of northern coniferous forests along the Rocky Mountains. Forages along streams or in dense second growth (Pitocchelli 1995).
Main food is insects. Feeds on or just above the ground (Pitocchelli 1995).
Nests in riparian habitat along river and stream banks, also steep coulee slopes, undergrowth of deciduous and mixed-woods forests, logging clearcuts and areas recovering from avalanches. Cup nest. Clutch size is 3 to 5 eggs. Eggs are short, ovate, creamy white, spotted neutral/brown (Pitocchelli 1995). Near Fortine, egg dates range from June 7 to June 30. In northwest Montana, it nests from second week in June into third week of July.