1Fish and Wildlife Population Ecology:The End Game…Golden-Cheeked Warbler (Dendroica chrysoparia)• breeds in closed-canopy woodlands, primarily Ashe juniper and oak• declined due to habitat loss and fragmentation from clearing of juniper for urban expansion, agriculture, and commercial harvestFort HoodFort Hood Army Post• Largest breeding population• BIG fire in 1996• Increased training demands2Recovery Credit System• Fort Hood “buys” the conservation rights to habitat patches on private lands• Unintentional loss of habitat on Fort Hood is “offset” by these purchases• Golden-cheek metapopulation remains “unharmed”How should off-post patches be valued?The Model• Stochastic, demographic, metapopulation projection modelStage S Temporal Variance (S) F Temporal Variance (F)HY 0.40 0.058 0 0SY 0.57 0.010 1.2 0.024ASY0.57 0.010 1.3 0.006The Model• Ceiling carrying capacity (K)• Various dispersal scenarios• Metapopulation Viability– After 20 years…– Mean final population sizeFort HoodBalcones NWR3The ModelPatch Id Patch Size (K) Distance from largest patchPop1 238 1Pop2 250 7Pop3 300 4Pop4 350 2Pop5 400 8Pop6 550 5Pop7 700 3Pop8 1000 6Pop9 6000 9Pop10 (i.e., Fort Hood ) 12371 0Characteristics of 10 hypothetical patches used to investigate the relationship between patch importance and patch size or distance from largest patch.DispersalScenario DescriptionNoD No dispersalSymD 15% symmetric dispersalSurvD15% symmetric dispersal; disperser survival declines with distanceKD Excess individuals above K become dispersersKSurvDSame as KD; disperser survival declines with distanceKSurvDVitalsSame as KSurvD; Larger pops. have higher survival and fecundityPredictors of Patch LeveragePatch Leverage (Lj) = Change in MFAChange in patch jVaried each patch size by +/- 200Patch Leverage (Lj)= f(original patch size and/or distance from largest patch)4ResultsScenario Mean Final AbundanceNoD 11182SymD 9870SurvD 7884KD 13037KSurvD 12212KSurvDVitals 16879Resultsy = 0.8153x + 11907110001150012000125001300013500100 200 300 400 500 600MFAKleverage metric(L4= 0.81) calculated for Population 4 Importance of Individual Populations 00.20.40.60.814 5 6 7 8 9 10L = ∆MFP/∆Kln(K)NoD5Importance of Individual Populations 00.20.40.60.814 6 8 10Lln(K)KDWith dispersal:• Original size predicts L• Smaller populations have greater leverageImportance of Individual Populations With dispersal and size-dependent vital rates:• Distance from largest (Fort Hood) predicts L• Closer populations have greater leverage00.20.40.60.810 2 4 6 8 10LDistanceKSurvDVitalsSo…• How much habitat needs to be conserved/added to Patch A to offset loss of 50 territories in Patch B?ˆˆBA BALL∆ = ∆ ×()( )1.74 0.14 ln 25050 931.74 0.14 ln 6000A− ×∆ = × =− ו Under dispersal scenario KD; Patch B initially held 250 territories and Patch A held
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