Estimating Greater Sage-grouse Juvenile Survival in Utah Utah State University David Dahlgren Terry Messmer David Koons

Introduction Info Need

Study Area Parker Mountain

Methods

Methods – Burkepile et al. 2002

Methods Hen Behavior

Methods Monitoring

Methods Veg and Arthropod Sampling

Brood Mixing

Methods Cause of mortality  Handling  Exposure  Predation Avian/Mammalian  Unknown

Methods Modeling  Manly and Schmutz JWM Maximum Likelihood Estimation (Version of the Mayfield Estimator) Heterogeneity - D Brood ID No. chicks start No. chicks end Age (days) Start Age (days) End Covariates Year etc Year etc Year etc Year etc Year etc Year etc Year etc.

Methods Modeling Survival  First Age Structure (weeks 1 to 6)  Used to assess covariates  AIC  Second Assess covariates  Temporal  Brood hen characteristics  Vegetation data  Arthropod data

Methods Modeling Survival  Assumptions Brood-mixing and right censoring Missing chicks Brood-mixing and missing chicks

Methods Modeling Survival  First Covariates Year Brood Type Hen Behavior (restricted data set) Hen Age (restricted data set) Hatch Date

Methods Modeling Survival  Second – Vegetation Covariates (restricted data set) Shrub cover and height Grass cover and height Forb cover and height  Third – Arthropod Covariates (2006, restricted data set) Hymenoptera (ants separate), Coleoptera, Lepidoptera, Orthoptera, miscellaneous, and total arthropods

Results Sample sizes  Total 2005 n = 89 chicks in 21 broods (mean = 4.24) 2006 n = 61 chicks in 21 broods (mean = 2.91)  Handling Death (2.6%) 2005 n = n = 1  Excluded from the survival analysis

Results Sample Sizes  Chick mass Mean = 29.5g (SE = 0.16) Transmitter averaged 5.1% (SE = ) of chick weight  Hen Behavior 43% Very protective (18/42) 38% Moderately protective (16/42) 19% Non-protective (8/42)

Results Sample Sizes  Brood Mixing 21% of marked chicks (31/146) 43% of marked broods (18/42) 45% of mixing events involved >1 chick (9/20) Occurred weeks 1 to 6 70% (14/20) in weeks 2 and 3 Radio-marked hen mortality (n = 2)

Results Sample Sizes  Chick Mortality n = 44 documented deaths n = 26 missing (assumed depredated) n = 6 exposure  Predation 91% (64/70)  Unknown 75% (48/64)  Mammalian 12.5% (8/64)  Avian 12.5% (8/64)

Results ModelKAICwiwi Age Specific Models (no covariates) age = (week1)+(week2)+(week3)+(week4)+(weeks5-6) age = (weeks1-2)+(weeks3-4)+(weeks5-6) age = (week1)+(week2)+(week3)+(weeks4-6) age = (weeks1-2)+(weeks3-6) age = (week1)+(week2)+(weeks3-6) age = (week1)+(weeks2-6) age = (weeks1-2)+(weeks4-6) age = (weeks 1-6) Covariate Models age* + brood type (regular or mixed) age* + hen age (yearling or adult) age* + year (2005 or 2006) age* + hen behavior (protectiveness) age* + hatch date (Julian days) First – Age parameterization : AIC difference between a model (i.e., model i) and the best performing model (i.e., model with the lowest AIC among the set of models examined). wi: Akaike model weight. * The best model of age = (week1) + (week2) + (week3) + (week4) + (weeks5-6) Second – Temporal and hen characteristics

Results ModelKAICwiwi Age Specific Models (no covariates) age = (week1)+(week2)+(week3)+(week4)+(weeks5-6) First – Age parameterization

Results ModelKAIC wiwi Covariate Models age* + brood type (regular or mixed) Second – Temporal and hen characteristics

Results Mean Survival to 42 days = 0.41 (SE =0.046) Chick Survival in Regular broods = 0.38 Chick Survival in Mixed broods = 0.61

Results Heterogeneity (D)  Chicks/brood = 3.5  For best model D = 1.10 (SE = 0.22)

Results ModelKAIC wiwi age* (NULL) Vegetation Covariates  Null Model is best

Results ModelKAIC wiwi age* + Ants age* (NULL) Arthropod Covariates  Entire 42 days  Ant model

Results ModelKAIC wiwi age* + Orthoptera Arthropod Covariates  Early brood-rearing (day 1-21)  Orthoptera (grasshopper) model Estimates not significant

Take Home Predation major cause of chick mortality However, survival was good (mean = 0.41) Our data suggested low dependence among brood mates for sage-grouse chicks Brood-mixing may be important to survival, needs further investigation There is evidence that Arthropods (especially Orthoptera) may aid chick survival, needs further investigation (> sample size)

Thanks PARM USU Extension Parker Mtn. Grazing Association Jack H. Berryman Institute UDWR USFS BLM NRCS SITLA Farm Bureau County Commissioners People Technicians Nathan Burkepile Jack Connelly Volunteers

Any Questions?