The December meeting of the Delta Stewardship Council included the first Delta Lead Scientist report given by Dr. Lisamarie Windham-Myers, who assumed the position of interim Delta Lead Scientist at the beginning of December.
Article spotlight: Priority Bird Conservation Areas in California’s Sacramento–San Joaquin Delta
The spotlighted article was published last summer in the San Francisco Estuary and Watershed Science Journal and was one of the most downloaded papers in 2023. The work by Kristen Dybala and co-authors synthesized data and provided a gap analysis of the spatial alignment of land birds and waterbirds with recommended protected areas in the Delta Plan’s ecosystem amendment where they align.
Dr. Windham-Myers noted that there have been very few landscape-scale studies about birds in the Delta, despite their crucial overall role in ecosystems, biodiversity, and human connections to the Delta. People appreciate birds through hunting, wildlife viewing, cultural heritage, and other activities.
The paper synthesized bird data from over 10,000 recent surveys for nine riparian land bird species, such as warblers, flycatchers, and sparrows, and 46 waterbird species, such as geese, cranes, shorebirds, dabbling and diving ducks. They then used the data to model the probability that specific birds will be present based on land use, climate, and hydrologic characteristics of each point in space.
“They even used things like the distance to nighttime roosts or waterways, so it’s a really robust spatial analysis,” said Dr. Windham-Myers.
Subsequently, they use the modeled probability of the presence of each of the 55 species at each location to identify the most probable locations for finding most of these species. Then, within each group, they broke the 55 species into groups. The 5% most essential locations for land birds and water birds were mapped. The research teams evaluated how many of the sites fell into areas that are prioritized for conservation in the Delta Plan or areas that had already been preserved, the land uses that they overlapped with, and how many areas are likely to be inundated by sea level rise by 2050 as identified in the Delta Adapts vulnerability assessment.
The result is the map shown on the slide. The priority bird conservation areas for land birds are shown in yellow; the priority waterbird habitats in blue; and where they co-locate is shown in red.
“The Delta Plan specifically specifies goals for providing bird habitat and migratory corridors, but Delta-scale spatial products and analyses on how birds use different habitats in the Delta have been scarce,” said Dr. Windham-Myers. “Perhaps even more important than the findings of these biodiversity hotspots in the northern peripheral wetland areas of the Delta is the finding that many of these priority bird conservation areas are either unprotected and dependent on agricultural land uses, especially the corn cropping and winter flooding land uses that are favored by waterbirds, which might be changing in the future. And then secondly, vulnerable to inundation by rising sea level by 2050.”
“Particularly useful, the research team mapped the locations where currently unprotected areas and forthcoming changes in crops due to climate change may have the most adverse effects on Delta bird conservation goals. So, it’s a clever analysis. It’s repeatable, predictive, and appreciates the dynamics of land use. The system is in flux. It’s changing. And this will help facilitate bird conservation in the long term.”
Priority Bird Conservation Areas in California’s Sacramento–San Joaquin Delta
Authors: Dybala, Kristen E.; Sesser, Kristin A.; Reiter, Matthew E.; Shuford, W. David; Golet, Gregory H.; Hickey, Catherine; Gardali, Thomas
Abstract: Conserving bird populations is a key goal for management of the Sacramento–San Joaquin Delta ecosystem and is likely to have effects well beyond its boundaries. To inform bird- conservation strategies, we identified Priority Bird Conservation Areas for riparian landbirds and waterbirds in the Delta, defined as the most valuable 5% of the landscape for each group. We synthesized data from 2,547 surveys for riparian landbirds and 7,820 surveys for waterbirds to develop predictive distribution models, which then informed spatial prioritization analyses. We identified a total of 26,019 ha that are a high priority for conserving riparian landbirds, waterbirds, or both, representing the most important places in the Delta to protect and manage, as well as strategic areas where adjacent restoration could expand valuable habitat. These Priority Bird Conservation Areas include the Yolo Bypass Wildlife Area, Cosumnes River Preserve, Stone Lakes National Wildlife Refuge, and bufferlands that surround the Sacramento County Regional Sanitation District. However, we also found that over 60% of the Priority Bird Conservation Areas are not currently protected, indicating a vulnerability to changes in land cover or land use. We recommend advancing strategies for bird conservation in the Delta by developing more specific objectives and priorities, extending these analyses to include other bird species, and planning to mitigate the loss of Priority Bird Conservation Areas where they are most vulnerable to land cover change. The predictive models and analysis framework we developed represent the current state of the science on areas important to bird conservation, while also providing a foundation for an evolving bird-conservation strategy that reflects the Delta’s continuously evolving knowledge base and landscape.
DELTA SCIENCE ACTIVITIES
Decision-making under deep uncertainty webinar: The Delta Independent Science Board is hosting a webinar series to support discussion and review of decision-making under deep uncertainty. The webinars bring in experts to discuss sources of uncertainties and approaches for managing them, as well as incorporating human behavior in anticipatory planning. The next webinar is scheduled for January 18 and will feature speakers from the Deltares Institute, including Dr. Marjolijn Haasnoot, Dr. Keren Bolter, and Dr. Kathryn Roscoe. The seminar will focus on Dynamic Adaptive Planning (DAP) when it’s most useful, and how it might be relevant for management in the Delta under deep uncertainty. Click here for the flyer. | Click here to register.
Peer Reviews: The Collaborative Science and Peer Review unit at the Council’s Delta Science Program administers the peer review program to support Delta decision-making. The unit was extremely busy in 2023; among the reviews completed are the Department of Water Resources’ Delivery Capability Report and the Bureau of Reclamation’s Water Temperature Modeling Program. More peer reviews are going forward in 2024, among them the review of the Bureau Reclamation’s fish and aquatic effects on long-term operations and the review of the Department of Water Resources summer-fall habitat action primarily for Delta smelt that begins in late February.
November Tidal Wetland Restoration Symposium: This symposium brought together stakeholders to discuss the state of the science for tidal wetland restoration. Speakers shared preliminary data on water quality, fish habitat use, invertebrate communities, and other aspects of their projects. Results show that restoration projects support fish and invertebrate communities similar to adjacent areas, and the shape and size of wetland channels determine where fish are found. Restoration projects can take decades to develop, and more research is needed to address many related uncertainties, but early results presented at this symposium indicate that these projects are likely to fulfill their objectives and provide additional support for a healthy Delta ecosystem. A recording of the symposium is available on the State Water Contractors YouTube channel.
Adaptive management resources in the works: At the Tidal Wetland Restoration Symposium, Delta Science Program’s environmental program manager, Dylan Chapelle, led a session on adaptive management, which discussed linking science to on-the-ground implementation of projects. The planning committee works with multiple interagency groups to develop a peer-reviewed assessment and other products to inform adaptive management of current and future projects.
Delta Science proposals: The call for Delta Research Solicitation Proposals is expected to be released in early 2024, with the award decisions anticipated in October. The focus of this solicitation is on participatory research to connect researchers to Delta Tribes and communities with the goal of improving the relevance of co-produced science questions and approaches.
California Sea Grant State Policy Fellowship Program: The Council has hosted 39 fellows through the program for the past eleven years. The 2023 cohort is wrapping up their work; five fellows gave a video presentation. The Council approved the contract to support the newest class of 2024 fellows at the September 2023 Council meeting.
