Hatching chronology of Blue Grouse (Dendragapus obscurus) in northeastern Oregon was determined from 431 immatures examined from 1981 to 1985. Young hatched from 1 May through 8 July; median hatching dates for the five years ranged from 27 May to 5 June. Peak hatching in Oregon occurred from one to four weeks earlier than in most portions of the range of Blue Grouse but were similar to north central Washington and Idaho. Variations in hatching dates possibly were related to rainfall.
Crawford, John A.; Van Dyke, Walter; Coggins, Victor; and St. Louis, Martin
"Hatching chronology of Blue Grouse in northeastern Oregon,"
Great Basin Naturalist: Vol. 46
, Article 20.
Available at: https://scholarsarchive.byu.edu/gbn/vol46/iss4/20