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Photo by Ron Stewart
Photo Copyright Ron Stewart
Osprey
Pandion haliaetus
NatureServe conservation status
Global (G-rank): G5
State (S-rank): S4B
External links
Species range
This species migrates through the state. Currently it breeds in Utah mailnly in the Flaming Gorge area.
Formerly it bred in other areas of the state. Hayward et al. (1976) stated: "All nesting records have been from mountain areas where there are lakes or reservoirs." There have been at least three breeding records for Fish Lake, Sevier County (Bee and Hutchings 1942, Hayward et al. 1976). Hayward (1931) reported nesting in Wasatch, Summit, and Duchesne counties. Eyre and Paul (1973) said that breeding pairs had been observed at Fish Lake, Panguitch Lake, Flaming Gorge, and the Green River.
Occurrences are known in Box Elder, Summit, Daggett, Uintah, Dichesne, Wasatch, Utah, Sevier, Garfield, and Kane counties.
Habitat
Behle and Perry (1975) mentioned habitat of this species in Utah as "mountain lakes". Hayward et al. (1976) cited sources from the late 19th century that indicated the former occurrence of this species "around the marshes of Great Salt Lake". Hayward et al. (1976) also stated: "All nesting records [in Utah] have been from mountain areas where there are lakes or reservoirs. . . . All of the nesting sites have been in tall trees."
Walters and Sorensen (1983) listed breeding habitats in Utah as cliffs, bluffs, etc.; coniferous forest; montane riparian woodlands (including narrow-leafed cottonwood, big-toothed maple, box elder, river birch, dogwood, alder, willows, etc.); lakes, reservoirs, ponds, sewage lagoons; and rivers and streams. They listed an additional habitat used during migration--desert riparian woodlands (including Fremont cottonwood, willows, etc.).
Threats or limiting factors
Though the breeding population has stabilized, many nesting subpopulations consist of single nests. These may be vulnerable to stochastic events. The drastic decline in breeding that took place in Utah probably occurred for the same reasons that it is known to have occurred elsewhere--namely environmental contamination by pesticides, such as DDT, which interferes with successful reproduction. These pesticides are carried through run-off into rivers and lakes where they are concentrated through the food chain, finally entering fish, the exclusive prey of ospreys.
