The following species are not on the official list of Montana birds for reasons explained after each species’ name. For each of the modern reports, evidence was convincing, but the report was not accepted because of the conservative stance taken by the MBRC on adding new species to the state list. QLL = quarter latilong.
Passenger Pigeon (Ectopistes migratorius). Various locations. Reported at least nine times by Lewis and Clark in 1805 and 1806 (Walcheck 1999). Reportedly collected during the Warren Expedition of 1856 (USNM 5418), by Cooper (1869a,b) in 1860, and by Coues (1878) in 1874. No extant specimens exist.
Common Crane (Grus grus). QLL 12B, 1999. Single-observer sighting with convincing details (MBRC 1999–039).
Pacific Golden-Plover (Pluvialis fulva). QLL 9C, 2001. Single-observer sighting with convincing details (MBRC 2002–002).
Harris’s Hawk (Parabuteo unicinctus). QLL 14B, 2013. Unbanded adult seen and photographed by many observers. Wild origin questionable owing to the popularity of this species with falconers (MBRC 2013–002).
Red-breasted Sapsucker (Sphyrapicus ruber). QLL 27B, 1984. Single-observer sighting with convincing details.
Gyrfalcon (Falco rusticolus). QLL 4A, 9 July 2017. Diagnostic photos of unbanded bird. Wild origin questionable owing to popularity of this species with falconers; or bird possibly recovered from injury that precluded normal migration (MBRC 2017-021).
Bell’s Vireo (Vireo bellii). QLL 24B, 1995; QLL 12B, 2007. One independent write-up with convincing details, and a single-observer sighting with convincing details, respectively.
Phainopepla (Phainopepla nitens). QLL 3A, 1962. Carried over from previous edition of MBD.
Cassin's Sparrow (Peucaea cassinii). QLL 29C, 1999. One independent write-up with convincing details (MBRC 1999–045).
Hermit Warbler (Setophaga occidentalis). QLL 38B, 2005. Single-observer sighting; hybrid could not be ruled out (MBRC 2005–027).
Cooper, J.G. 1869a. The fauna of Montana Territory. II. Birds. American Naturalist 3:31-35, 73-84.
Cooper, J.G. 1869b. Notes on the fauna of the Upper Missouri. American Naturalist 3:294-299.
Coues, E. 1878. Field-notes on birds observed in Dakota and Montana along the forty-ninth parallel during the seasons of 1873 and 1874. Bulletin of the United States Geological and Geographical Survey of the Territories 4(3):545-661.
Walcheck, K.C. 1999. The Lewis and Clark Expedition: Montana’s first bird inventory through the eyes of Lewis and Clark. Lewis and Clark Interpretive Association, Great Falls, Montana.