Distribution model objects for tidal wetland birds in the Sacramento-San Joaquin Delta

Summary: This is an R Data file (.rds) containing predictive distribution models of class `gbm` for each of 3 secretive marsh bird focal species and 4 tidal wetland songbird focal species. For use in predicting suitable habitat in the Sacramento-San Joaquin Delta and Suisun Marsh based on land cover data. Description: These predictive models were developed to predict the probability of species presence as a function of the surrounding landscape, facilitating predictions of species distributions and the extent of suitable habitat over the entire landscape. The .RData object is structured as a list containing individual model objects of class `gbm` for each species. Models were developed using Boosted Regression Trees, implemented in R using the R packages `dismo` (Hijmans et al. 2021) and `gbm` (Greenwell et al. 2020). Models were developed from pre-existing bird survey data, including a total of 3,738 unique surveys collected from 594 unique survey locations throughout the Delta and Suisun Marsh between 2015 and 2024. Information about species presence at a subset of these locations (n=36) was supplemented by over 4200 hours of acoustic data collected in 2023. Abbreviation Definitions: AMBI: American Bittern (Botaurus lentiginosus) BLRA: California Black Rail (Laterallus jamaicensis coturniculus) COYE: Common Yellowthroat (Geothlypis trichas) LEBI: Least Bittern (Botaurus exilis) MAWR: Marsh Wren (Cistothorus palustris) SOSP: Song Sparrow (Melospiza melodia) YBCH: Yellow-breasted Chat (Icteria virens) Purpose: These models were used to predict the distribution of each species and group across a baseline Delta landscape, which were then used to conduct a spatial prioritization analysis using Zonation to identify Priority Bird Conservation Areas for secretive marsh bird and songbird focal species. In addition, the models were used to predict distributions for alternative scenarios of future tidal wetland restoration and to evaluate the net change from the baseline distributions in the total area of suitable habitat. These models are required for evaluating the change in Biodiversity Support benefits using the R package `DeltaMultipleBenefits`, which provides the code and work flow for repeating these scenario analyses or analyzing new scenarios. Funding Statement: These data were developed as part of the project "Trade-offs and Co-benefits of Landscape Change in the Sacramento-San Joaquin River Delta: Phase II Tidal Wetlands and Restoration", which funded by the Water Quality, Supply, and Infrastructure Improvement Act of 2014 (Proposition 1, CWC § 79707) through the Delta Water Quality and Ecosystem Restoration Program, Grant Agreement Number – Q2296017, administered by the California Department of Fish and Wildlife.