<hir Li\ini; Rfsoitrccs — hjti'rior Wfs! 



3.H 



pairs of owls were located by imitating their 

 calls with the human voice or using taped 

 broadcasts of their calls to elicit a response from 

 the owls (Forsman 1983). The surveys were 

 conducted during each breeding season ( 1 

 April-31 August) from 1989 through 1993. 

 Target areas were visited four times during the 

 breeding season to search for owls. Spotted owl 

 callers ("hooters") conducted searches by 

 "hooting" at stations located on night-time sur- 

 vey routes placed within search areas. Hooters 

 conducted daytime visits to sites where spotted 

 owls were heard at night in order to find nests 

 and count young. 



Historical Records 



Historical records of Mexican spotted owls 

 on the Colorado Plateau date back to the 192()"s 

 (McDonald et al. 1990). The earliest record in 

 the canyonlands was from Zion National Park 

 in June 1928. A single owl was reported in 

 August 1957. in Davis Gulch, a tributary of the 

 Escalante Riser in southern Utah. Three birds 

 were seen in July 1958, in a small side canyon 

 of Glen Canyon National Recreation Area, and 

 another was observed at the mouth of the 

 Escalante River. The most northerly occunence 

 of a spotted owl on the Colorado Plateau was 

 recorded in September 1958, in the Book Cliff 

 Mountains. Spotted owls have been observed 

 occasionally since the early 1970's throughout 

 the canyonlands of southern Utah. Kertell 

 (1977) detected spotted owls at six locations in 

 Zion National Park in the early I970"s. The 

 species accounts suggest that spotted owls were 

 widely dispersed throughout the canyonlands of 

 the Colorado Plateau, especially in deeply erod- 

 ed sandstone gorges. 



Field Survey Results 



About 202,500 ha (500,000 acres) were sur- 

 veyed from 1990 to 1993 on U.S. Forest 

 Service lands, and more than 483 km (300 mi) 

 of BLM canyons were surveyed from 1991 to 

 1993. Surveys were also conducted in portions 

 of Grand Canyon, Capitol Reef, Canyonlands. 

 and Zion national parks, as well as Natural 

 Bridges and Navajo national monuments. 

 Seventy-six spotted owls (26 pairs and 24 single 

 adults) were detected at 50 locations: 6 on U.S. 

 Forest Service lands, 12 on BLM lands. 1 on 

 state lands, and 31 on National Park Service 

 lands (Fig. 2). 



Groups or subpopulations of owls were dis- 

 tributed among several landscape areas spread 

 across the northwest portion of the Colorado 

 Plateau including the greater Zion National 



Park area: the greater Capitol Reef area: the 

 Dirty Devil River watershed: Canyonlands 

 National Park: and near Elk Ridge and Dark 

 Canyon on the Manti LaSal National Forest. 



Mexican spotted owls were widely distrib- 

 uted and appeared coincident with canyon habi- 

 tat. Canyon habitats on the Colorado Plateau are 

 discontinuous and reflect the naturally frag- 

 mented topographic conditions of the plateau 

 region. This patchy landscape could explain the 

 patchy locations of surveyed spotted owls. A 

 study conducted in Zion National Park found 

 owls nesting and roosting in humid, nanow 

 canyons with dense understories (Rinkevich 

 1991). Since many owls on the Colorado 

 Plateau were found in similar habitat, the owls 

 may be selecting these canyons because of their 

 unique habitat features: large cliffs that provide 

 escape cover to avoid predation, shaded roost 

 sites to avoid high summer temperatures, patch- 

 es of forest vegetation, and a\ailability of suit- 

 able prey. 



Relatively few owls were found in the 

 canyonlands area compared with forest sites in 

 Arizona and New Mexico; thus, canyonland 

 owl sites may need special protection. Further 

 surveys should be conducted across USDI lands 

 to more accurately assess distribution and habi- 

 tat of spotted owls. 



References 



Federal Register 1993. Endangered and threatened wildlife 



and plants: final nile to list the Mexican spotted owl as a 



threatened species. Federal Register 58:14248-14271. 

 Forsman. E.D. 1983. Methods and materials for locating 



and studying spotted owls. Gen. Tech. Rep. PNW-162. 



U.S. Forest Service. Pacific Northwest Forest and Range 



Experiment Station. Portland. OR. 8 pp. 

 Ganey. J.L. 1988. Distribution and habitat ecology of 



Mexican spotted owls in Arizona. M.S. thesis. Northern 



Arizona University. Flagstaff. 229 pp. 

 Ganey. J.L.. and R.P. Balda. 1989. Distribution and habitat 



use of Mexican spotted owls in Arizona. Condor 9 1 :3.'i5- 



361. 

 Gutierrez, R.J. 1989. Distribution and abundance of spotted 



owls in Zion National Park. National Park Service. Order 



PX-I200-9-C820. 69 pp. 

 Kertell. K. 1977. The spotted owl at Zion National Park. 



Western Birds 8:147-150. 

 McDonald. C.B.. J. Andersen. J.C. Lewis. R. Mesta, A. 



Ratzliff. T.J. Tibbots. and S.O. Williams III. 1990. 



Mexican spotted owl status review. U.S. Fish and 



Wildlife Service. Endangered Species Rep. 20. 



Alberquerque. NM. 85 pp. 

 Rinkevich. S.E. 1991. Distribution and habitat characteris- 

 tics of Mexican spotted owls in Zion National Park. Utah. 



M.S. thesis, Humboldt State University. Areata. CA. 62 



pp. 

 Thornbury. W. 1965. Regional geomorphology of the 



United States. John Wiley and Sons. New York. 609 pp. 

 Youngblood. A. P.. and R.L. Mauk. 1985. Coniferous forest 



habitat types of central and southern Utah. Gen. Tech. 



Rep. INT- 1 87. U.S. Forest Service. Intemiountain Forest 



and Range Experiment Station, Ogden. UT. 89 pp. 



Fig. 2. Distribution of Mexican 

 spotted owls in canyonlands of 

 southern Utah, representing the 

 northwest portion of the Colorado 

 Plateau Physiographic Province. 



For further information: 



David W. Willey 



National Biological Service 



Colorado Plateau Research Station 



Northern Arizona University 



Box 5640 



Flagstaff, AZ 86011 



