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| IRS990/ActivityOrMissionDesc | 0 | ACR is a system of wildlife sanctuaries and centers of nature education in the counties of Marin and Sonoma, California. ACR protects the natural resources of its sanctuaries while fostering an understanding and appreciation of these environments. |
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| IRS990/BooksInCareOfDetail/PersonNm | 0 | GARY SCHICK |
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| IRS990/BooksInCareOfDetail/USAddress/CityNm | 0 | STINSON BEACH |
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| IRS990/Desc | 0 | The ACR Conservation Science Program activities included several scientific investigations on herons & egrets, shorebirds, waterbirds, and landbirds. We conducted avian point-count and breeding bird surveys at ACRs Modini Mayacamas Preserves and surrounding areas of the central Mayacamas Mountains, completed eight baywide shorebird surveys and four baywide waterbirds surveys on Tomales Bay, and monitored the nesting performance of herons and egrets at all known colony sites in the northern San Francisco Bay region (Marin, Sonoma, Napa, Solano, and Contra Costa counties). ACRs annual conservation science journal, The Ardeid, is in its 28th consecutive year of publication. |
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| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 15 | 0.50 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 16 | 0.50 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 17 | 0.50 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 18 | 0.50 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 19 | 0.50 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 20 | 38.00 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 21 | 38.00 |
| IRS990/Form990PartVIISectionAGrp/AverageHoursPerWeekRt | 22 | 38.00 |
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| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 1 | X |
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| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 4 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 5 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 6 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 7 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 8 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 9 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 10 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 11 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 12 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 13 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 14 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 15 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 16 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 17 | X |
| IRS990/Form990PartVIISectionAGrp/IndividualTrusteeOrDirectorInd | 18 | X |
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| IRS990/Form990PartVIISectionAGrp/OfficerInd | 0 | X |
| IRS990/Form990PartVIISectionAGrp/OfficerInd | 1 | X |
| IRS990/Form990PartVIISectionAGrp/OfficerInd | 2 | X |
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| IRS990/Form990PartVIISectionAGrp/PersonNm | 4 | JUDE STALKER |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 5 | BARBARA WINTER |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 6 | JOAN TURNER |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 7 | JOE MUELLER |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 8 | ANDRE BREWSTER |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 9 | AMY BLACKSTONE |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 10 | REBECCA SIMON |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 11 | NANCY LILLY |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 12 | MICHAEL MAGATELLI |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 13 | KYLE KIRWAN |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 14 | MARK TARPEY-SCHWED |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 15 | JUDY PROKUPEK |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 16 | BILL BRIDGES |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 17 | CAROL LYNN WOOD |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 18 | ANNE MONTGOMERY |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 19 | IVAN OBOLENSKY |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 20 | GARY SCHICK |
| IRS990/Form990PartVIISectionAGrp/PersonNm | 21 | JOHN PETERSEN |
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| IRS990/Form990PartVIISectionAGrp/TitleTxt | 3 | Treasurer |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 4 | Director |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 5 | Director |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 6 | Secretary |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 7 | Director |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 8 | Director |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 9 | Director |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 10 | Director |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 11 | Director |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 12 | Director |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 13 | Director |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 14 | Director |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 15 | President |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 16 | Director |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 17 | Director |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 18 | Vice President |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 19 | Director |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 20 | Controller |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 21 | Executive Dir. |
| IRS990/Form990PartVIISectionAGrp/TitleTxt | 22 | DIR. FIN. & OPS |
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| IRS990/Form990TFiledInd | 0 | false |
| IRS990/FormationYr | 0 | 1962 |
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| IRS990/FSAuditedInd | 0 | true |
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| IRS990/GainOrLossGrp/SecuritiesAmt | 0 | 1260499 |
| IRS990/GamingActivitiesInd | 0 | false |
| IRS990/GoverningBodyVotingMembersCnt | 0 | 20 |
| IRS990/GrantsToDomesticIndividualsGrp/TotalAmt | 0 | 0 |
| IRS990/GrantsToDomesticOrgsGrp/TotalAmt | 0 | 0 |
| IRS990/GrantsToIndividualsInd | 0 | false |
| IRS990/GrantsToOrganizationsInd | 0 | false |
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| IRS990/GrossAmountSalesAssetsGrp/SecuritiesAmt | 0 | 4408013 |
| IRS990/GrossReceiptsAmt | 0 | 7686961 |
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| IRS990/InformationTechnologyGrp/FundraisingAmt | 0 | 17534 |
| IRS990/InformationTechnologyGrp/ManagementAndGeneralAmt | 0 | 30134 |
| IRS990/InformationTechnologyGrp/ProgramServicesAmt | 0 | 104371 |
| IRS990/InformationTechnologyGrp/TotalAmt | 0 | 152039 |
| IRS990/InsuranceGrp/FundraisingAmt | 0 | 6747 |
| IRS990/InsuranceGrp/ManagementAndGeneralAmt | 0 | 11596 |
| IRS990/InsuranceGrp/ProgramServicesAmt | 0 | 40163 |
| IRS990/InsuranceGrp/TotalAmt | 0 | 58506 |
| IRS990/IntangibleAssetsGrp/EOYAmt | 0 | 0 |
| IRS990/InterestGrp/TotalAmt | 0 | 0 |
| IRS990/InventoriesForSaleOrUseGrp/BOYAmt | 0 | 22953 |
| IRS990/InventoriesForSaleOrUseGrp/EOYAmt | 0 | 20871 |
| IRS990/InvestmentIncomeGrp/ExclusionAmt | 0 | 817236 |
| IRS990/InvestmentIncomeGrp/TotalRevenueColumnAmt | 0 | 817236 |
| IRS990/InvestmentInJointVentureInd | 0 | false |
| IRS990/InvestmentsOtherSecuritiesGrp/EOYAmt | 0 | 0 |
| IRS990/InvestmentsProgramRelatedGrp/EOYAmt | 0 | 0 |
| IRS990/InvestmentsPubTradedSecGrp/BOYAmt | 0 | 26907482 |
| IRS990/InvestmentsPubTradedSecGrp/EOYAmt | 0 | 27178532 |
| IRS990/InvestTaxExemptBondsInd | 0 | false |
| IRS990/IRPDocumentCnt | 0 | 22 |
| IRS990/IRPDocumentW2GCnt | 0 | 0 |
| IRS990/LandBldgEquipAccumDeprecAmt | 0 | 3447722 |
| IRS990/LandBldgEquipBasisNetGrp/BOYAmt | 0 | 10412272 |
| IRS990/LandBldgEquipBasisNetGrp/EOYAmt | 0 | 10674011 |
| IRS990/LandBldgEquipCostOrOtherBssAmt | 0 | 14121733 |
| IRS990/LegalDomicileStateCd | 0 | CA |
| IRS990/LessCostOthBasisSalesExpnssGrp/OtherAmt | 0 | 24854 |
| IRS990/LessCostOthBasisSalesExpnssGrp/SecuritiesAmt | 0 | 3147514 |
| IRS990/LicensedMoreThanOneStateInd | 0 | false |
| IRS990/LoanOutstandingInd | 0 | false |
| IRS990/LobbyingActivitiesInd | 0 | false |
| IRS990/LocalChaptersInd | 0 | false |
| IRS990/MaterialDiversionOrMisuseInd | 0 | false |
| IRS990/MembersOrStockholdersInd | 0 | false |
| IRS990/MethodOfAccountingAccrualInd | 0 | X |
| IRS990/MinutesOfCommitteesInd | 0 | true |
| IRS990/MinutesOfGoverningBodyInd | 0 | true |
| IRS990/MissionDesc | 0 | Audubon Canyon Ranch protects nature through land preservation, nature education, and conservation science. |
| IRS990/MoreThan5000KToIndividualsInd | 0 | false |
| IRS990/MoreThan5000KToOrgInd | 0 | false |
| IRS990/NetAssetsOrFundBalancesBOYAmt | 0 | 38952348 |
| IRS990/NetAssetsOrFundBalancesEOYAmt | 0 | 39650117 |
| IRS990/NetGainOrLossInvestmentsGrp/ExclusionAmt | 0 | 1235645 |
| IRS990/NetGainOrLossInvestmentsGrp/TotalRevenueColumnAmt | 0 | 1235645 |
| IRS990/NetIncmFromFundraisingEvtGrp/TotalRevenueColumnAmt | 0 | 0 |
| IRS990/NetIncomeFromGamingGrp/TotalRevenueColumnAmt | 0 | 0 |
| IRS990/NetIncomeOrLossGrp/ExclusionAmt | 0 | 1684 |
| IRS990/NetIncomeOrLossGrp/TotalRevenueColumnAmt | 0 | 1684 |
| IRS990/NetRentalIncomeOrLossGrp/TotalRevenueColumnAmt | 0 | 0 |
| IRS990/NetUnrlzdGainsLossesInvstAmt | 0 | -31719 |
| IRS990/NoncashContributionsAmt | 0 | 14794 |
| IRS990/NondeductibleContributionsInd | 0 | false |
| IRS990/OccupancyGrp/FundraisingAmt | 0 | 26346 |
| IRS990/OccupancyGrp/ManagementAndGeneralAmt | 0 | 29665 |
| IRS990/OccupancyGrp/ProgramServicesAmt | 0 | 202101 |
| IRS990/OccupancyGrp/TotalAmt | 0 | 258112 |
| IRS990/OfficeExpensesGrp/FundraisingAmt | 0 | 12660 |
| IRS990/OfficeExpensesGrp/ManagementAndGeneralAmt | 0 | 21758 |
| IRS990/OfficeExpensesGrp/ProgramServicesAmt | 0 | 75360 |
| IRS990/OfficeExpensesGrp/TotalAmt | 0 | 109778 |
| IRS990/OfficerMailingAddressInd | 0 | false |
| IRS990/OnBehalfOfIssuerInd | 0 | false |
| IRS990/OperateHospitalInd | 0 | false |
| IRS990/Organization501c3Ind | 0 | X |
| IRS990/OrganizationFollowsSFAS117Ind | 0 | X |
| IRS990/OrgFiledInLieuOfForm1041Ind | 0 | false |
| IRS990/OtherAssetsTotalGrp/BOYAmt | 0 | 81310 |
| IRS990/OtherAssetsTotalGrp/EOYAmt | 0 | 81613 |
| IRS990/OtherEmployeeBenefitsGrp/FundraisingAmt | 0 | 29896 |
| IRS990/OtherEmployeeBenefitsGrp/ManagementAndGeneralAmt | 0 | 51379 |
| IRS990/OtherEmployeeBenefitsGrp/ProgramServicesAmt | 0 | 177957 |
| IRS990/OtherEmployeeBenefitsGrp/TotalAmt | 0 | 259232 |
| IRS990/OtherExpensesGrp/Desc | 0 | RESEARCH AND SPECIAL PROJECTS |
| IRS990/OtherExpensesGrp/Desc | 1 | LIBRARY AND PUBLIC EDUCATION |
| IRS990/OtherExpensesGrp/Desc | 2 | OTHER |
| IRS990/OtherExpensesGrp/Desc | 3 | COMMUNITY OUTREACH AND RECOG. |
| IRS990/OtherExpensesGrp/FundraisingAmt | 0 | 9637 |
| IRS990/OtherExpensesGrp/FundraisingAmt | 1 | 54220 |
| IRS990/OtherExpensesGrp/ManagementAndGeneralAmt | 0 | 10227 |
| IRS990/OtherExpensesGrp/ProgramServicesAmt | 0 | 79519 |
| IRS990/OtherExpensesGrp/ProgramServicesAmt | 1 | 78174 |