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Data and scripts from: Migratory shorebird response to non-tidal wetland dynamics at an internationally important inland Pacific Flyway stopover

Publication ,  Dataset
Schaffer Smith, D; Swenson, J
February 23, 2018

The objectives of this study are to characterize broad and fine scale-habitat variability at inland shorebird stopover wetlands, and to assess the response of shorebirds to habitat availability changes over 20+ years. Inland wetlands, particularly flood-irrigated rice, are not as well studied as coastal areas, and there is little understanding of their seasonal and interannual variability, and the implications for the future of these charismatic birds. We focus on spring migration (March May), when these resources are most critical for migratory birds. The Sacramento Valley is site of International Importance for shorebirds and is ideally suited for this analysis; the valley hosts a diversity of wetlands, including 95% of California’s rice production, and shorebirds have been monitored consistently here for 20 years. We address the following questions: 1) What has been the contemporary distribution, and variability of inundation across the Sacramento Valley during spring? 2) To what extent does flooded habitat extent vary within and between different wetland types? 3) How have shorebirds responded to changes in broad and fine-scale habitat fluctuations? We captured broad-scale habitat (inundation extent) approximately every 16 days during using Landsat satellite imagery from 1984 to 2015. Field data collection was targeted to fill knowledge gaps with regard to wetland contours and water depth variation within different wetland types. We used a stratified random sampling approach to select a representative set of 23 managed wetlands in Sacramento National Wildlife Refuge Complex. To measure finescale habitat variation, we mapped refuge wetland topography (1-3cm vertical accuracy), and deployed capacitance sensors to monitor water depth at refuge wetlands from March 2015 - May 2016. Limited water depth measurements were also collected in rice fields using ibutton thermocron temperature sensors in the spring of 2015. Water depth records were used to map suitable habitat (water depth<10cm) within mapped wetlands; we also used historical Landsat inundation maps to interpolate water depth going back to 1996 to analyze long-term habitat suitability patterns for mapped wetlands. To analyze the drivers of habitat availability and the influence of broad and fine-scale habitat availability on shorebird use at refuge wetlands, we used a generalized joint attribute modelling (GJAM) aproach. We analyzed the effects of climate, water availability, and water management.

Duke Scholars

DOI

Publication Date

February 23, 2018
 

DOI

Publication Date

February 23, 2018