DISTRIBUTION OF THE SPOTTED OWL IN CALIFORNIA GORDON I. GOULD, JR., CaliforniaDepartment of Fish and Game, 1416 Ninth Street, Sacramento, California 95814 The Fish and Wildlife Service(Bureau of Sport Fisheriesand Wildlife 1973) listed the Spotted Owl (Strix occidentalis)as a specieswhose status needed to be determined. Until recently the statusof this secre- tive woodland raptor was unknown by governmentwildlife agencies and consideredto be rare. Furthermore, land practiceswere reducing the habitat of the Spotted Owl. For thesereasons, the California De- partment of Fish and Game and the United StatesForest Servicecoop- eratively initiated and financed this study in July 1973. In 1974 the National Park Service became involved. In 1973 I conductedsurveys in the forested mountainsin northwest- ern California. From March to September1974 surveyswere conducted throughoutthe remainingareas of coniferousforest in California. Dur- ing the 1975, 1976 and 1977 breedingseasons, voids in the rangewere checkedand known sites monitored by the author and other agency biologists. METHODS SpottedOwls arc located easily,especially during the breedingseason (March through June) by usingrecordings or vocal imitations of their calls. Variations of the location call describedby Forsmart(1975) wcrc used. In surveyswhere stopswcrc madeevery one-half mile, owlsusual- ly respondedto calls within 10 minutes. Frequently, these owls will approachthe caller to defend their territory. Apparently only Spotted Owls that are paired adults will respondvigorously to calls(Forsman 1977). Where one owl was located, the mate would usually appear if imitation of calls continued. Sexescan be differentiated by their calls. The call of the female is higherpitched than the male'sand sheshows a greater use of the contact and agitated contact callsdescribed by Fors- mart (1975). Sightingsof Spotted Owls noted in this report are limited to those where responsesto calls were elicited, where calling was heard, and where pairs or adults with young were observed. Therefore, the lo- cations noted herein should be representativeof breedingterritories. Though many visual observationshave been made of Spotted Owls throughoutthe state, many of theseare not representativeof possible breedingterritories. Young Spotted Owls dispersein the fall and as a result have produceda number of sightingsnot truly representativeof the owl's habitat. Among the more notable of theseare sightingsof singleindividuals at WoodsonBridge State Park, TehamaCounty, on 24 Western Birds 8:131-146, 1977 131 SPOTTED OWL IN CALIFORNIA November1972; San DiegoSports Arena, San DiegoCounty, on 19 No- vember 1973; Cottonwood Canyon, RiversideCounty, in November 1973; and Chico Cemetery, Butte County, from 31 January to 1 Feb- ruary 1975. A searchof literature and of museumspecimens disclosed 102 his- torical localitiesof occurrence. Questionnairescompleted by field or- nithologistsprovided another 81 localities. These were used as a basis for establishingsurveys. Other localitieswere checkedwhen convenient. RESULTS PAST DISTRIBUTION Until recently,Grinnell and Miller's (1944) work includedthe only informationavailable regarding the distributionof the CaliforniaSpot- ted Owl (S. o. occidentalis)and the NorthernSpotted Owl (S. o. cau- rina). A few additionallocality recordshave been publishedfor the Lake Tahoe area (Johnsonand Russell1962), SequoiaNational Park (Sumner and Dixon 1953), the Laguna Mountains (Samsand Stott 1959), and other scatteredlocalities (most notably in Audubon Field Notes/AmericanBirds). Thesesightings are usefulin determiningthe historicaldistribution of Spotted Owls in California. California Spotted Owls havebeen recordedat sitesin San Luis Obis- po and Montereycounties, outside of the rangedefined by Grinnelland Miller (1944). Although the majority of sightingsfrom this area have been reportedin the last 10 years,Bent (1938) reportedSpotted Owls in San Luis Obispo County. Additional extentionshave been noted westwardto Solvangin SantaBarbara County and souththrough the CuyamacaMountains in San Diego County. The distributionof CaliforniaSpotted Owl in the SierraNevada has changedlittle from that describedby Grinnell and Miller (1944). Two recent sightings(Cogswell and Pray 1955; Sequoia-KingsCanyon Na- tional Park specimentaken 1965) have extendedslightly the known range into central Tulare County. Johnsonand Russell(1962) found Spotted Owls directly north of Lake Tahoe, only a few miles west of the California-Nevadaborder. SpottedOwls have not been reported from Nevada,although suitable habitat may exist in the Lake Tahoe area. Prior to this study,Spotted Owls had not beenreported from the area betweenPlacer County and LassenNational Park eventhough this areawas included in the rangedescribed by Grinnelland Miller (1944). PRESENT DISTRIBUTION Spotted Owls, apparently occupyingterritories, were found at 317 sitesin 36 counties(Appendix 1). Of these,122 siteswere in the range of the NorthernSpotted Owl and195 werein the rangeof the California Spotted Owl (Figure 1). 132 SPOTTED OWL IN CALIFORNIA Two pairs were located east of the previouslydescribed range of the Northern Spotted Owl in Shastaand Siskiyou counties. Future survey work in this area may indicatethat thesepairs near Mr. ShastaCity and Lake McCloud are not isolatedbut are within an areawhere the pop- ulation is sparse. The California Spotted Owl was found in severalareas outside of the rangedescribed by Grinnell and Miller (1944). In the southcoast area, a large northward extensionof the previouslydescribed range in the coastal mountains through Santa Barbara, San Luis Obispo and Mon- Figure 1. Distribution of the Spotted Owl (Strix occidentalis) in California. The dashedline indicatesthe rangedescribed by Grinnelland Miller (1944). Dots rep- resentlocalities of presumedbreeding territories, 1973-1977. 133 SPOTTED OWL IN CALIFORNIA terey countieswas substantiated. Also, a southern extensionof the known range in San Diego County through CuyamacaRancho State Park and into the LagunaMountains was noted. In the southernSierra Nevada,Spotted Owls were found in Sequoia National Park and on the SequoiaNational Forest. Thesesightings ex- tended the previouslyknown rangefrom the General Grant Groveand Redwood Mountain areas in northern Tulare County, south through Tulare County and into Kern County as far as BreckenridgeMountain. Sightingsof the California Spotted Owl in the remainingSierran part of its rangegenerally were within the rangedescribed by Grinnell and Miller (1944). Sightingsmade during this study demonstrateda greater continuity in distribution than had beenreported previously. Most no- table were sightingsin E1 Dorado, Nevada,Yuba, Sierra, Butte and Plu- mas counties. Sightingsmade during this study extendedthe previouslydescribed range into the easternSierra Nevada. Numerousrecords in the upper drainagesof the Feather River in PlumasCounty are eastof the bound- ariesof the old rangebut thereare nonein drainagesof the eastside of this sectionof the SierraNevada. Three siteswere identified duringthis study in the Carson River drainage,an east side drainage,in Alpine County. Presently,these are the only known active siteson the east side of the Sierra Nevada; the site north of Lake Tahoe (Johnson and Russell 1962) was checkedand no evidenceof the two reported pairs was found. POPULATION SIZE Four hundredand eighty-fourSpotted Owls (191 Northern, 293 Cal- ifornia), presumablyrepresenting 317 pairs, were located during this study. An accurateestimation of the statewidepopulation cannot be derivedfrom thesefigures since the amount of suitablehabitat surveyed and the total available have not been calculated. Enoughdata havebeen collected to delineatea numberof population concentrations. The largestconcentration of SpottedOwls in the state, along the South Fork of the Trinity River and into the Yolla Bolly Wil- dernessArea, Trinity and Tehama counties,and a major concentration on Point ReyesPeninsula, Marin County,are populationcenters for the Northern Spotted Owl. The largestconcentrations of the California SpottedOwl existalong the WesternDivide and in the GreenhornMoun- tains, Tulare and Kern counties,Sequoia National Park, Tulare and Fres- no counties, northwest of Yosemite Valley, Tuolumne and Mariposa counties,and in the Deep Creek and Green Valley area, San Bernardino County. Populationsare scatteredin Monterey,San Luis Obispo and SantaBarbara counties. Throughout the remainderof their rangeSpot- ted Owlsappear to be ratherevenly distributed in the availablehabitat. 134 SPOTTED OWL IN CALIFORNIA 135 SPOTTED OWL IN CALIFORNIA POPULATION TREND Sincethe sizeof pastor presentSpotted Owl populationsin Califor- nia is unknown,direct comparisonsof populationsize cannot be made. However,during the studyan attemptwas made to checka numberof historicalreports more than 30 yearsold (Appendix2). Spottedowls werepresent at 72%of the historicalsites checked. HABITAT REQUIREMENTS Elevation, timber type (using United States Forest Servicetimber type designations),topographic type, water availabilityand slopeexpo- sure were noted at 192 sites where Spotted Owls were found (Gould 1974). The habitat characteristicsnoted below are representativeof territoriesdefended by Spotted Owls. In the north coastarea, Spotted Owls were found frequently from 18 to 250 m elevation, an area dominated by Redwood (Sequoiasem- pervirens) and occasionallyBishop Pine (Pinus muricata) (Table 1). Grand Fir (Abiesgrandis), Douglas-fir (Pseudotsuga menziesii),