Recovery Plan for the Northern Spotted Owl - DRAFT

Recovery Plan for the Northern Spotted Owl - DRAFT Recovery Plan for the Northern Spotted Owl - DRAFT

10.07.2015 Views

Table 2.3. Estimated spotted owl habitat and number of pairs of spotted owls locatedduring a 5-year period on all lands in Washington, Oregon, and California.Estimated Acres of Spotted Owl Nesting, Roosting,and Foraging Habitat by Timber CapabilityOwl PairsUnsuitable Suited Non-Landowner or Agencya Reservedb for Harvestc for Harvest Total Acres Reserved reservedd TotalsFS, Washington 500,024 804,000 747,000 2,051,024 56 417 473'FS, Oregon 389,974 1,058,000 1,447,000 2,894,974 89 1,242 1,331IFS, California 304,268 519,000 305,000 1,128,268 64 550 614fBLM, Oregon 158,000 - 873,472 1,031,472 1 540 5416BLM, California 13,000 - 6,000 19,000 0 11 11eNPS, Washington 480,000 - - 480,000 31 0 316NPS, Oregon 50,000 - - 50,000 4 0 4'NPS, California 40,000 - - 40,000 2 0 2eIndian lands, Washington NA NA 257,000 257,000 0 51 51fIndian lands, Oregon NA NA 54,000 54,000 0 18 18fIndian lands, California NA NA 32,000 32,000 0 28 28'FWS, Washington 1,700 NA 5,000 6,700 0 0 OfFWS, Oregon 4,100 NA NA 4,100 0 0 OfWDNR NA NA NA NA 0 33 33'WDW 0 NA 5,000 5,000 0 0 OfState parks, Washington 2,000 0 0 2,000 0 0 OfCities of Seattle, Tacoma, 0 0 1,500 1,500 0 0 OfWashingtonODF 0 NA 77,200 77,200 0 30 30'State parks, Oregon 8,000 0 0 8,000 2 0 2'Counties and cities, Oregon NA NA NA NA 1 0 1fCDF NA NA NA NA 0 4 4eState parks, California 56,000 0 0 56,000 0 10 0oeBLM/TNC, California 6,500 0 0 6,500 0 0 oeNAS, California 600 0 0 600 0 0 oePrivate, California NA NA NA NA NA 235 235ePrivate, Oregon NA NA NA NA 0 50 50'I Private, Washington NA NA NA NA 0 31 31fTotals 2,014,166 2,381,000 3,810,172 8,205,338 250 3,250 3,500NA = Reliable estimates not available.alnformation obtained from landowners or state wildlife agencies.bWithdrawn from timber harvest (e g wilderness, national park, research natural area).cLands unsuited for timber production because of allocation to other uses by land management plans, ortechnically unsuited for timber production because of soils problems or difficulty of regeneration.I doWl pairs that are not on lands not withdrawn from timber harvest or that are on lands withdrawn on an interim basis.eFive-year survey period = 1986-1990.'Five-year survey period = 1987-1991.FS = U S. Forest ServiceBLM = U.S. Bureau of Land ManagementNPS = National Park ServiceDNR = Washington Department of Natural ResourcesWDW = Washington Department of WildlifeODF = Oregon Department of ForestryNAS = National Audubon SocietyTNC = The Nature ConservancyCDF = California Department of Forestry and Fire ProtectionNote: Numbers used in this table contain updates that were not available for the mapped data used in the geographic information system (GIS).Numbers cited elsewhere in the document were derived from the GIS and are not Identical to numbers In the table.34

uted across the range of ecological conditions in the province and thesignificant reduction of linkages and demographic support to adjacentprovinces.Moderate: The threat is not severe at the present time but would beexpected to become severe within the next 10 generations if correctivemeasures are not undertaken. In most cases, these corrective measureswill have to include actions to reverse present conditions and trends.Low: The threat to the population is currently low and is expected toremain low as long as conservation measures are undertaken.Unknown: Inadequate information currently exists to assess the threat.Not all threats are equally important, and no attempt was made to assignthem weights. Comparisons between provinces cannot be based simplyon the number of threats that fall in specific categories, e.g., the numberof threats rated severe or moderate.Low Populations. Small populations are vulnerable to extinction from anumber of causes. Random fluctuations in environmental conditions (environmentalstochasticity) and age and sex structure of populations (demographicstochasticity), along with potential loss of genetic variability (geneticstochasticity) are most likely to influence small populations.Declining Populations. Population trends for northern spotted owls havebeen difficult to estimate because many of the adult and subadult birds areprobably nonterritorial and difficult to detect on surveys. These "floaters" maywait for several years for a territory to become available before they pair andbegin reproducing. If a population is declining, the number of territorial birdsis likely to remain nearly constant as long as floaters remain, because territorialbirds that die are replaced rapidly from the pool of floaters. Thus, territorialbirds are the only segment of the population that can be monitored effectively,but trends in this segment of the population do not necessarily providean accurate estimate of trends in the overall population.One way to solve this problem is by analyzing birth and death rates. Theserates then can be used to calculate whether the population is declining. Theanalyses, because they depend on how birth and death rates vary with age, areoften complex. The underlying principle, however, is simply that the birth rateequals the death rate in a stable population. If the birth rate is less than thedeath rate, then population size declines.The 1990 Status Review (USDI 1990) provided estimates of the rate of populationchange for two populations, one in northern California and one in southernOregon. Both populations were shown to be declining. By the fall of 1991,data from 2 more years were available from these areas, and data were alsoavailable from three other study areas (Figure 2.3).At the request of the Recovery Team, a group of 12 researchers was convenedat Colorado State University to analyze this new information. The resultsindicated that all five populations declined from 1985 to 1991 (Table 2.5). Theestimated rates of decline varied from 7 to 16 percent and averaged about 10percent. The analyses also suggested that the rate of decline may be increasing.Details of the analysis are summarized in Appendix C. These new estimatesreinforce the widely held belief that populations of spotted owls are decliningthroughout all or most of their range.Limited Habitat. Throughout much of the range of the northern spotted owl,habitat is highly fragmented and is resulting in decreased owl productivity and35

Table 2.3. Estimated spotted owl habitat and number of pairs of spotted owls locatedduring a 5-year period on all lands in Washington, Oregon, and Cali<strong>for</strong>nia.Estimated Acres of <strong>Spotted</strong> <strong>Owl</strong> Nesting, Roosting,and Foraging Habitat by Timber Capability<strong>Owl</strong> PairsUnsuitable Suited Non-Landowner or Agencya Reservedb <strong>for</strong> Harvestc <strong>for</strong> Harvest Total Acres Reserved reservedd TotalsFS, Washington 500,024 804,000 747,000 2,051,024 56 417 473'FS, Oregon 389,974 1,058,000 1,447,000 2,894,974 89 1,242 1,331IFS, Cali<strong>for</strong>nia 304,268 519,000 305,000 1,128,268 64 550 614fBLM, Oregon 158,000 - 873,472 1,031,472 1 540 5416BLM, Cali<strong>for</strong>nia 13,000 - 6,000 19,000 0 11 11eNPS, Washington 480,000 - - 480,000 31 0 316NPS, Oregon 50,000 - - 50,000 4 0 4'NPS, Cali<strong>for</strong>nia 40,000 - - 40,000 2 0 2eIndian lands, Washington NA NA 257,000 257,000 0 51 51fIndian lands, Oregon NA NA 54,000 54,000 0 18 18fIndian lands, Cali<strong>for</strong>nia NA NA 32,000 32,000 0 28 28'FWS, Washington 1,700 NA 5,000 6,700 0 0 OfFWS, Oregon 4,100 NA NA 4,100 0 0 OfWDNR NA NA NA NA 0 33 33'WDW 0 NA 5,000 5,000 0 0 OfState parks, Washington 2,000 0 0 2,000 0 0 OfCities of Seattle, Tacoma, 0 0 1,500 1,500 0 0 OfWashingtonODF 0 NA 77,200 77,200 0 30 30'State parks, Oregon 8,000 0 0 8,000 2 0 2'Counties and cities, Oregon NA NA NA NA 1 0 1fCDF NA NA NA NA 0 4 4eState parks, Cali<strong>for</strong>nia 56,000 0 0 56,000 0 10 0oeBLM/TNC, Cali<strong>for</strong>nia 6,500 0 0 6,500 0 0 oeNAS, Cali<strong>for</strong>nia 600 0 0 600 0 0 oePrivate, Cali<strong>for</strong>nia NA NA NA NA NA 235 235ePrivate, Oregon NA NA NA NA 0 50 50'I Private, Washington NA NA NA NA 0 31 31fTotals 2,014,166 2,381,000 3,810,172 8,205,338 250 3,250 3,500NA = Reliable estimates not available.aln<strong>for</strong>mation obtained from landowners or state wildlife agencies.bWithdrawn from timber harvest (e g wilderness, national park, research natural area).cLands unsuited <strong>for</strong> timber production because of allocation to o<strong>the</strong>r uses by land management plans, ortechnically unsuited <strong>for</strong> timber production because of soils problems or difficulty of regeneration.I doWl pairs that are not on lands not withdrawn from timber harvest or that are on lands withdrawn on an interim basis.eFive-year survey period = 1986-1990.'Five-year survey period = 1987-1991.FS = U S. Forest ServiceBLM = U.S. Bureau of Land ManagementNPS = National Park ServiceDNR = Washington Department of Natural ResourcesWDW = Washington Department of WildlifeODF = Oregon Department of ForestryNAS = National Audubon SocietyTNC = The Nature ConservancyCDF = Cali<strong>for</strong>nia Department of Forestry and Fire ProtectionNote: Numbers used in this table contain updates that were not available <strong>for</strong> <strong>the</strong> mapped data used in <strong>the</strong> geographic in<strong>for</strong>mation system (GIS).Numbers cited elsewhere in <strong>the</strong> document were derived from <strong>the</strong> GIS and are not Identical to numbers In <strong>the</strong> table.34

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