Day and Night Habitat Associations of Wintering Dunlin (<i>Calidris alpina</i>) within an Agriculture-Wetland Mosaic

Barbaree, Blake A.; Reiter, Matthew E.; Hickey, Catherine M.; Page, Gary W.

doi:10.1675/063.038.0106

Cited by 13 publications

(19 citation statements)

References 21 publications

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“…Our finding that the minimum water extent occurs during the peak of spring shore-bird migration (Figs. 6, 7) corroborates other studies (Barbaree et al, 2015;Central Valley Joint Venture, 2006) and stresses the need for conservation and management actions focused on this particular window of time. The decline in March water extent that we quantified gives further credence to concern that the Sacramento Valley may not provide sufficient habitat for migrating shorebirds, particularly during drought conditions (Central Valley Joint Venture, 2006).…”

Section: Discussionsupporting

confidence: 85%

“…More than 90% of the historically occurring wetlands have been lost in the Central Valley (Frayer et al, 1989). The Sacramento Valley hosts 96% of California's flood-irrigated rice (~20% of U.S production, Central Valley Joint Venture, 2006; Strum et al, 2013), which serves as important surrogate habitat for shorebirds in areas with high wetland loss (Barbaree et al, 2015;Elphick, 2000Elphick, , 2010. Despite extensive historical wetland loss, the Sacramento Valley is recognized by the Western Hemisphere Shorebird Reserve Network as a site of international importance (Western Hemisphere Shorebird Reserve Network, 2009).…”

Section: Study Areamentioning

confidence: 99%

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Three decades of Landsat-derived spring surface water dynamics in an agricultural wetland mosaic; Implications for migratory shorebirds

Schaffer‐Smith

Swenson

Barbaree

et al. 2017

Remote Sensing of Environment

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Satellite measurements of surface water offer promise for understanding wetland habitat availability at broad spatial and temporal scales; reliable habitat is crucial for the persistence of migratory shorebirds that depend on wetland networks. We analyzed water extent dynamics within wetland habitats at a globally important shorebird stopover site for a 1983-2015 Landsat time series, and evaluated the effect of climate on water extent. A range of methods can detect open water from imagery, including supervised classification approaches and thresholds for spectral bands and indices. Thresholds provide a time advantage; however, there is no universally superior index, nor single best threshold for all instances. We used random forest to model the presence or absence of water from >6200 reference pixels, and derived an optimal water probability threshold for our study area using receiver operating characteristic curves. An optimized mid-infrared (1.5-1.7 μm) threshold identified open water in the Sacramento Valley of California at 30-m resolution with an average of 90% producer's accuracy, comparable to approaches that require more intensive user input. SLC-off Landsat 7 imagery was integrated by applying a customized interpolation that mapped water in missing data gaps with 99% user's accuracy. On average we detected open water on ~26000 ha (~3% of the study area) in early April at the peak of shorebird migration, while water extent increased five-fold after the migration rush. Over the last three decades, late March water extent declined by ~1300 ha per year, primarily due to changes in the extent and timing of agricultural flood-irrigation. Water within shorebird habitats was significantly associated with an index of water availability at the peak of migration. Our approach can be used to optimize thresholds for time series analysis and near-real-time mapping in other regions, and requires only marginally more time than generating a confusion matrix.

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Section: Discussionsupporting

confidence: 85%

Section: Study Areamentioning

confidence: 99%

Three decades of Landsat-derived spring surface water dynamics in an agricultural wetland mosaic; Implications for migratory shorebirds

Schaffer‐Smith

Swenson

Barbaree

et al. 2017

Remote Sensing of Environment

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“…Flooded rice fields provide abundant and accessible food resources, and may be especially attractive to shorebirds due to reduced predation risk compared to semi‐natural wetland systems (Elphick and Oring , Barbaree et al. ). Recently the highest shorebird densities recorded for agricultural land in the Sacramento Valley were documented in temporary shallow water habitat provided in rice fields through the Bird Returns payment for services program (Golet et al.…”

Section: Discussionmentioning

confidence: 99%

“…) and provide important surrogate habitat for shorebirds and other waterbirds (Elphick , , Barbaree et al. ). Sacramento NWR Complex contains approximately 25% of the total emergent non‐tidal wetland area in the Sacramento Valley mapped by the National Wetland Inventory (U.S.…”

Section: Methodsmentioning

confidence: 99%

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Quantifying shorebird habitat in managed wetlands by modeling shallow water depth dynamics

Schaffer‐Smith

Swenson

Reiter

et al. 2018

Ecological Applications

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Over 50% of Western Hemisphere shorebird species are in decline due to ongoing habitat loss and degradation. In some regions of high wetland loss, shorebirds are heavily reliant on a core network of remaining human-managed wetlands during migration journeys in the spring and fall. While most refuges have been designed and managed to match the habitat needs of waterfowl, shorebirds typically require much shallower water (<10 cm deep). Traditional static habitat modeling approaches at relatively coarse spatial and temporal resolution are insufficient to capture dynamic changes within this narrow water depth range. Our objectives were to (1) develop a method to quantify shallow water habitat distributions in inland non-tidal wetlands, and (2) to assess how water management practices affect the amount of shorebird habitat in Sacramento National Wildlife Refuge Complex. We produced water depth distributions and modeled optimal habitat (<10 cm deep) within 23 managed wetlands using high-resolution topography and fixed-point water depth records. We also demonstrated that habitat availability, specifically suitable water depth ranges, can be tracked from satellite imagery and high-resolution topography. We found that wetlands with lower topographic roughness may have a higher potential to provide shorebird habitat and that strategically reducing water levels could increase habitat extent. Over 50% of the wetlands measured provided optimal habitat across <10% of their area at the peak of migration in early April, and most provided a brief duration of shallow water habitat. Reducing water volumes could increase the proportion of optimal habitat by 1-1,678% (mean = 294%) compared to actual volumes measured at peak spring migration in 2016. For wetlands with a high habitat potential, beginning wetland drawdown earlier and extending drawdown time could dramatically improve habitat conditions at the peak of shorebird migration. Our approach can be adapted to track dynamic hydrologic changes at broader spatial scales as additional high-resolution topographic (e.g., lidar, drone imagery photogrammetry) and optical remote sensing data (e.g., planet imagery, drone photography) become available.

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Using ricelands to provide temporary shorebird habitat during migration

Golet

Low

Avery

et al. 2018

Ecological Applications

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To help mitigate large wetland losses in California, The Nature Conservancy launched a dynamic conservation incentive program to create temporary wetland habitats in harvested and fallow rice fields for shorebirds migrating along the Pacific Flyway. Farmers were invited to participate in a reverse auction bidding process and winning bids were selected based on their cost and potential to provide high quality shorebird habitat. This was done in 2014 and 2015, for separate enrollment periods that overlapped with spring and fall migration, both before and after the traditional post-harvest flooding period. To assess the success of the program, we monitored shorebird use of fields that were enrolled (treatments), and others that were subject to typical rice farm management (controls). To put these observations in context, we used satellites to simultaneously monitor the extent of shallow-water habitat across the ~215,000 ha of ricelands in the area. Results showed that providing habitat during migration, when it is typically unavailable in rice fields, yielded the largest average shorebird densities ever reported for agriculture in the region. Treatment fields had significantly greater shorebird density, richness and diversity than control fields in both spring and fall (especially September-early October, and late March-early April), but in fall the difference was greater. Shorebird responses to habitat provisioning, and regional habitat conditions, were variable from year to year, and highly dynamic within a given season. Overall, shorebirds densities were found to be negatively related to the total amount of flooded habitat in the rice landscape. Factors that affected habitat availability included allocation schedules of water deliveries from reservoirs, and rainfall patterns, both of which were influenced by drought. Collectively, these results suggest that appropriately managed agricultural lands have great potential to provide high value habitat for shorebirds during times of habitat deficit, including migration, and that fall may be a particularly impactful time to create additional habitat. Migratory species face great challenges due to the climate change, conversion of historical stopover sites, and other factors, but dynamic conservation programs offer promise that, at least in certain instances, their needs can still be met.

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Day and Night Habitat Associations of Wintering Dunlin (Calidris alpina) within an Agriculture-Wetland Mosaic

Cited by 13 publications

References 21 publications

Three decades of Landsat-derived spring surface water dynamics in an agricultural wetland mosaic; Implications for migratory shorebirds

Three decades of Landsat-derived spring surface water dynamics in an agricultural wetland mosaic; Implications for migratory shorebirds

Quantifying shorebird habitat in managed wetlands by modeling shallow water depth dynamics

Using ricelands to provide temporary shorebird habitat during migration

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