Central Valley of California landcover compatibility with Sandhill Crane habitat use from 2008 to 2023
Description
Our dataset includes the proportional landcover within priority wintering areas for Sandhill Cranes (Grus canadensis) in the Central Valley of California from 2008 to 2023. This can be used to examine changes in landcover within these priority areas over time as well as to compare differences among the various priority areas. Specifically, the dataset demonstrates changes in landcovers pertinent to the provisioning of Sandhill Crane habitat in the region from 2008 to 2023. A 2-km buffer was applied to 7,187 Sandhill Crane use locations collected from 1991 to 2013 via various studies to help delineate priority wintering areas. The buffer distance reflects the average daily flight distance of Greater Sandhill Cranes from roosting to foraging sites in the region. Spatial gaps in the study area were not filled, nor were the edges of delineated priority wintering areas smoothed. Much of the data used for this project was previously described in Ivey et al. (2016). After defining the study area, we incorporated proportional landcover data from the United States Department of Agriculture's Cropland Data Layer (CDL), which has a 30-meter resolution (USDA 2024). We then grouped existing landcover categories into those with similar taxonomy, considering Sandhill Crane habitat use preferences. Next, we merged all landcovers into two groups that categorized them as compatible (i.e., “suitable”) or incompatible (i.e., “unsuitable”) with Sandhill Crane use based on existing habitat studies and expert knowledge. The dataset is provided as five separate comma-separated value (CSV) files: (1) foraging locations used to delineate the study area (Foraging_Locations.csv), (2) proportional landcover classified as compatible or incompatible with Sandhill Crane habitat use (Compatible_Landcover.csv), (3) relative coverage of landcover types important for Sandhill Crane habitat provisioning (Functional_Landcover.csv), (4) reclassification of CDL categories as compatible or incompatible (CDL_Reclass_Compatible.csv), and (5) reclassification of CDL categories by functional relevance to Sandhill Crane habitat (CDL_Reclass_Functional.csv). This dataset has the capacity to directly inform decisions regarding Sandhill Crane habitat conservation in the Central Valley of California. It can be analyzed in several ways, including via Mann-Kendall Trend Tests (τ). Key Citations: Ivey, G.L., C.P. Herziger, D.A. Hardt, and G.H. Golet. 2016. Historic and recent winter sandhill crane distribution in California. Proceedings of the North American Crane Workshop 13:54-66. United States Department of Agriculture (USDA). 2024. Cropland Data Layer. National Agricultural Statistics Service (NASS), Marketing and Information Services Office, Washington, D.C., USA. <https://croplandcros.scinet.usda.gov/>
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Crane Locational Data We compiled crane foraging locations from multiple sources, including radio telemetry of 77 marked cranes and field observations from a 2008–2009 Delta study (Ivey et al. 2015). We also used winter flock surveys on private lands across the Central Valley (Dec 2012–Feb 2013) and 2012–2013 eBird reports, following Ivey et al. (2016). These datasets helped define four priority Central Valley wintering regions: (1) Sacramento Valley, (2) Sacramento–San Joaquin Delta, (3) northern San Joaquin Valley, and (4) southern San Joaquin Valley. Landcover Data We created a 2-km buffer around all crane locations to capture nearby foraging and roosting habitats, reflecting typical daily dispersal distances (Ivey et al. 2015). These buffered polygons defined the study area without smoothing or filling gaps. Annual land cover data from the USDA Cropland Data Layer (CDL) for 2008–2023 (30-m resolution; USDA 2024) were clipped to the 2-km buffered polygons, restricting analysis to relevant crane wintering areas. The total study area was 4,260 km², divided into Sacramento Valley (1,827 km²), Sacramento–San Joaquin Delta (1,430 km²), Northern San Joaquin Valley (738 km²), and Southern San Joaquin Valley (265 km²). Sandhill Cranes use diverse habitats, including grasslands, wetlands, and row crops. Prior Delta studies (Ivey et al. 2025) reported no use of orchards, vineyards, blueberries, or nursery areas, likely due to limited visibility and food availability. We applied two classification approaches: (1) grouping CDL codes by crop taxonomy, structure, and phenology (e.g., “Alfalfa,” “Rice,” “Orchard and Vineyard”) to examine landcover changes relevant to Sandhill Crane ecology, and (2) broadly assigning landcover compatibility with wintering habitat use patterns based on expert knowledge and prior studies. All geospatial processing and raster analyses were conducted in Python 3.11.10 using the ArcPy package in ArcGIS Pro (v3.5.0). Raster clips and reclassifications used the 2-km buffered observations and annual summaries of total area (hectares) were extracted for each reclassified landcover and habitat compatibility class. Key Citations: Ivey, G. L., B. D. Dugger, C. P. Herziger, M. L. Casazza, and J. P. Fleskes. 2015. Wintering ecology of sympatric subspecies of sandhill crane: Correlations between body size, site fidelity, and movement patterns. Condor 117:518-529. Ivey, G. L., B. D. Dugger, C. P. Herziger, M. L. Casazza, and J. P. Fleskes. 2025. Habitat use by sandhill cranes wintering in the agricultural landscape of the Sacramento-San Joaquin River Delta of California. Proceedings of the North American Crane Workshop 16:14-34.