Klaver, R.W., J.M. Smith, J.J. Claar, B.L. Betts, and L.C. Peterson. 1982. Osprey surveys in the Flathead Valley, Montana, 1977 to 1980. The Murrelet 63:40‑45
Abstract
The Osprey nesting population was monitored in the Flathead Valley between 1977 and 1980 by initiating data collection for the lower Flathead River and continuing surveys on Flathead Lake. Results indicate a 'healthy' population with an average of 2.25 young per successful nest (2.18 young per active nest) on the lower Flathead River between 1978 and 1980, an average of 1.94 young per successful nest on the south half of Flathead Lake in 1979 and 1980, and 2.48 young per successful nest in the North Valley in 1979. The Flathead Valley, as a whole, produced 2.24 fledglings per successful nest. These data and other observations indicate a continuing upward trend in the Osprey population. The lower breeding rate for Ospreys nesting on Flathead Lake compared with those along the river may be due to the lake's oligotrophic nature and the longer time the birds spend traveling between fishing and nest sites.