Great Basin Naturalist Volume 56 Number 2 Article 6 4-29-1996 Geographical review of the historical and current status of Ospreys (Pandion haliaetus) in Utah Clark S. Monson Brigham Young University Follow this and additional works at: https://scholarsarchive.byu.edu/gbn Recommended Citation Monson, Clark S. (1996) "Geographical review of the historical and current status of Ospreys (Pandion haliaetus) in Utah," Great Basin Naturalist: Vol. 56 : No. 2 , Article 6. Available at: https://scholarsarchive.byu.edu/gbn/vol56/iss2/6 This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. Great Basin Naturalist 56(2), © 1996, pp. 150-156 GEOGRAPHICAL REVIEW OF THE HISTORICAL AND CURRENT STATUS OF OSPREYS (PANDION HALIAETUS) IN UTAH Clark S. Monson1 ABSTRACT,-Small numbers of Ospreys (Pandion lUlliaetus) are known to have nested historically in Utah. A precise baseline figure is unavailable, but the 19th-century Osprey population in Utah probably consisted ofat least 15 breeding pairs scattered in 4 geographic regions. Human persecution is believed to have caused the abandonment ofnesting ter­ ritories along the Wasatch Front and in the western Uinta Mountains by 1900 and 1960, respectively. Osprey popula­ tions in the southern plateaus and Green River areas, however, began increasing in the late 1970s. Several recent nesting attempts and numerous summer sightings at nontraditional and abandoned historical sites in Utah suggest the Osprey is also expanding its range in Utah. High productivity for local pairs and long-range dispersal from more northerly Osprey populations are discussed as sources for the current surge in Utah's Osprey population, which now consists of approxi­ mately 35 breeding pairs. Key words: Osprey, Pandion haliaetus, raptor, Flaming Gorge Reservoir, dispersal. The Osprey (Pandion haliaetwJ) is one ofthe their range in Utah. This paper reviews histor­ most widely distributed species ofraptors dur­ ical Osprey breeding territories in Utah, sub­ ing the breeding period. The extent of its cos­ sequent population declines, and current mopolitan range is exceeded by only 2 other Osprey population and range expansion in raptors: tbe Peregrine Falcon (Falco peregri­ Utah. nWi) (Cade 1982, del Hoyo et al. 1994) and Barn Owl (Tyto alha) (Marti 1985, Eckert and GEOGRAPHIC HISTORY OF THE Karalus 1987). Despite tbe Osprey's broad OSPREY IN UTAH geographic distribution, local populations occur in fragmented and low densities in much of Nesting Ospreys have been reported from the species' range (Bent 1937, Palmer 1988, del 4 geographical areas of Utah (Fig. 1): the Hoyo et al. 1994). This scenario holds true for Wasatch Front, Uinta Mountains, southern pla­ most of the intermountain region of the west­ teaus, and Green River (Table 1). Accounts of ern United States (Henny 1986, Johnsgard early ornithologists, naturalists, and egg col­ 1990). In Utah, Osprey distribution has been lectors indicate the Osprey was a regular sum­ particularly limited. Recently, however, several mer resident and breeder in Utah. Allen (1872) personal summer observations of Ospreys over found them along the Great Salt Lake marshes 140 km from known breeding pairs prompted west of Ogden, and Hensbaw (1874) saw them an investigation into the possible occurrence of at Utall Lake near Provo. Neither discussed Ospreys at other nontraditional Utalliocalities. nest observations in these areas, but R. G. Bee A survey ofindividuals from the U.S. Forest (unpublished ornithological notes) mentioned Service, Utah Division of Wildlife Resources, that Ospreys formerly nested along the sbores Utah State Parks, and otber persons familiar and tributaries of Utah Lake (Fig. 1; Table 1, with Osprey ecology was conducted during region A). 1994-95. The survey revealed many Osprey Other records were for the Uinta Mountains sightings and several nesting attempts between (Fig. 1; Table 1, region B).]. D. Daynes (unpub­ 1 June and 15 August at numerous lakes, res­ lished ornithological notes) described the ervoirs, and rivers from nearly every region of repeated use of an Osprey nest from 1915 to the state since 1990. These sigbtings represent 1938 on tbe Weber River, 20 km east of Oak­ the first widespread effort by Ospreys to expand ley, Summit County. Also, Hayward (1931) JDepltrhncnl ofGeogruphy, Brigham Young lIniv6nity. Provo. VI' 84602-5526. 150 1996] OSPREY STATUS IN UTAH 151 I , o kilometers 80 ., \ : ~.. •• , •• ,~ , ! • ,. • ~-- .. Fig. 1. Known historical distribution of nesting Ospreys in Utah: A. Wasatch Front; B, western Uinta Mountains; C. southern plate."\us; D, Green River. surveyed (8 July-21 August 1930) birds in the and Hutchings (1942) specifically cite Mirror western Uinlas where Summit, Duchesne, and and Trial lakes as having Osprey nests, Twomey Wasatch counties converge. While not giving (1942: 382) visited an occupied nest between actual locations, he said a few Ospreys nested 16 and 20 July 1932 at the north end of Mirror in the Mirror and Tryol [sic] lakes region. Bee Lake, "Wasatch County." This nest was actually 152 GREAT BASIN NATURALIST [Volume 56 TABLE L Nesting populations ofOspreys in Utah. S1~TUS Hegion IIistorical pairs Current pairs Historical Events A: Wasatch l<i'ont Unknown 1 Although numerous records ofOspreys nest­ ing in Utah exist, these birds have apparently B: Uinta Mountins 5-8 0 undergone 2 separate declines. The 1st decline c: Southern plateaus 2-4 8-11 involved Ospreys nesting along the Wasatch Front (Fig. 1). During winter 1848-49, depreda­ 20-25 D: Green River 6-8 tions upon livestock, poultry, and grain led to a much-puhlicized contest to kill the "wasters and destroyers" (Arrington 1958: 51). Hundreds of mammalian predators and thousands of raptors in Duchesne County and perhaps the same were killed (Arrington 1958). Ospreys would nest Hayward et al. (1976) referred to when have been on their southern v.rintering grounds they listed Wasatch County as a former nest­ during this assault on local predators, but the ing area. R. G. Bee (unpnblished ornithological incident suggests that early pioneers in Utah notes) also cited single pairs at Fish, Scout, and treated all carnivores and birds of prey with Lily lakes in the western Uintas. On 23 May contempt. Other similar hunts followed, and 40 1945, Bee recorded that a game warden in years later the Utal, Legislature implemented a Duchesne informed him of 2 pairs at Moon law awarding bounties for the killing of preda­ Lake and another pair at an unidentified Uinta tors (Rawley 1985). Rewards were available for lake. several species of fish~eating birds including Other early observers of Osprey nests in Ospreys. The destruction that this bounty in­ Utah include Wolfe and Cottam (Hayward et flicted upon fish-eating hirds in the name of al. 1976), who, along with Bee and Hutchings "conservation" was significant and is vividly (1942), saw Ospreys nest at Fish Lake (not the described by Pritchett et al. (1981). Uinta Mountains lake with the same name), The attitudes ofearly residents toward pred­ Sevier County, beginning in 1928 (Fig. 1; Table ators, coupled with laws encouraging their 1, region C). On 18 July 1936, R. G. Bee (un­ destruction, may have led to the Osprey's published ornithological notes) visited the Fish extirpation from the \Vasatch Front (Fig. 1; Lake nest. A local rancher told him Ospreys Table 1, region A) around the turn of the cen­ had used that particular nesting site for at tury. In 1935, R. G. Bee (unpublished ornitho­ least 20 years. logical notes) speculated that human persecu­ tion caused the abandonment of Osprey nests Behle et al. (1958) noted a pair of Ospreys near Utah Lake. Bee did not record when these in southwestern Utah at Navajo Lake, Kane Ospreys disappeared, hut his manner of re­ County, on 17 and 18 June 1950 (Fig. 1; Table flection on their absence suggests the loss 1, region C). This particular territory (and an occurred well before his 1935 notation. additional site at nearby Panguitch Lake, The 2nd period ofOsprey decline occurred Garfield County) bas been used regularly since in the western Uinta Mountains (Fig. 1). The Behle's discovery (Eyre and Paol 1973, Salt Uinta Mountain nests that Daynes, Bee, Hay­ Lake Tribune, 13 August 1978, Walters 1981, ward, and Twomey reported were observed Anonymous 1989). before, but apparently not after, the 1950s and Ospreys also nested along the Green River, 1960s when Osprey colonies along the eastern northeastern Utah (Fig. 1; Table 1, region D). seaboard were decimated by organochlorine On 23 and 24 July 1959, C. M. White and C. compounds (Palmer 1988, Poole 1989). Although Bosley (White and Behle 1960) located 2 nests the impact of synthetic agricultural biocides along this river in Horseshoe Canyon, Daggett upon Ospreys in Utah is unknown, Ospreys in County. Both nests contained 2 young. An other areas of the western United States were additional nest was discovered on the Green generally less affected by environmental con­ River in Uintah County by M, Horton in June taminants than eastern populations (Poole 1974 (Behle 1981). White (1969) suggested the 1989, White 1994). total population of Ospreys nesting along the Another possible reason for the decline of Green River probably consisted of6-8 pairs. Ospreys in the Uinta Mountains is indiscrimi- 1996] OSPREY STATUS IN UTAH 153 nate shooting resulting from a hostile attitude hatchery, Wasatch County (Fig. 2A). In 1995 a by local residents (Bee unpublished ornitho­ 2nd pair built a nest 2 km away at Deer Creek logical notes, Twomey 1942). Many Ospreys Reservoir on a 5-m-high artificial platform were formerly shot at northern Utah fish erected for Ospreys (Fig.