The Science of Setting Conservation Objectives for Birds in California’s Central Valley: An Introduction

https://doi.org/10.15447/sfews.2017v15iss1art1&lt;Abstracts are not associated with Editorials. --The Editors of SFEWS.</p

A Bioenergetics Approach to Setting Conservation Objectives for Non-Breeding Shorebirds in California’s Central Valley

An extensive network of managed wetlands and flooded agriculture provides habitat for migrating and wintering shorebirds in California’s Central Valley. Yet with over 90% of historical wetlands in the region lost, Central Valley shorebird populations are likely diminished and limited by available habitat. To identify the timing and magnitude of any habitat limitations during the non-breeding season, we developed a bioenergetics model that examined whether currently available shorebird foraging habitat is sufficient to meet the daily energy requirements of the shorebird community, at either the baseline population size surveyed from 1992 to 1995 or double this size, which we defined as our long-term (100-year) population objectives. Using recent estimates of the extent of managed wetlands and flooded agriculture, satellite imagery of surface water, energy content of benthic invertebrates, and shorebird metabolic rates, we estimated that shorebird foraging habitat in the Central Valley is currently limited during the fall. If the population sizes were doubled, we estimated substantial energy shortfalls in the fall (late July–September) and spring (mid-March–April) totaling 4.02 billion kJ (95% CI: 2.23–5.83) and 7.79 billion kJ (2.00–14.14), respectively. We then estimated long-term habitat objectives as the minimum additional shorebird foraging habitat required to eliminate these energy shortfalls; the corresponding short-term (10-year) habitat objectives are to maintain an additional 2,160 ha (5,337 ac) of shallow (&lt;10 cm) open water area in the fall and 4,692 ha (11,594 ac) in the spring. Because the Central Valley is one of the most important regions in the Pacific Flyway for migrating and wintering shorebirds, we expect that achieving these habitat objectives will benefit shorebirds well beyond the Central Valley. Our bioenergetics approach provides a transparent, repeatable process for identifying the timing and magnitude of habitat limitations as well as the most efficient strategies for achieving conservation objectives

A Bioenergetics Approach to Setting Conservation Objectives for Non-Breeding Shorebirds in California’s Central Valley

An extensive network of managed wetlands and flooded agriculture provides habitat for migrating and wintering shorebirds in California’s Central Valley. Yet with over 90% of historical wetlands in the region lost, Central Valley shorebird populations are likely diminished and limited by available habitat. To identify the timing and magnitude of any habitat limitations during the non-breeding season, we developed a bioenergetics model that examined whether currently available shorebird foraging habitat is sufficient to meet the daily energy requirements of the shorebird community, at either the baseline population size surveyed from 1992 to 1995 or double this size, which we defined as our long-term (100-year) population objectives. Using recent estimates of the extent of managed wetlands and flooded agriculture, satellite imagery of surface water, energy content of benthic invertebrates, and shorebird metabolic rates, we estimated that shorebird foraging habitat in the Central Valley is currently limited during the fall. If the population sizes were doubled, we estimated substantial energy shortfalls in the fall (late July–September) and spring (mid-March–April) totaling 4.02 billion kJ (95% CI: 2.23–5.83) and 7.79 billion kJ (2.00–14.14), respectively. We then estimated long-term habitat objectives as the minimum additional shorebird foraging habitat required to eliminate these energy shortfalls; the corresponding short-term (10-year) habitat objectives are to maintain an additional 2,160 ha (5,337 ac) of shallow (&lt;10 cm) open water area in the fall and 4,692 ha (11,594 ac) in the spring. Because the Central Valley is one of the most important regions in the Pacific Flyway for migrating and wintering shorebirds, we expect that achieving these habitat objectives will benefit shorebirds well beyond the Central Valley. Our bioenergetics approach provides a transparent, repeatable process for identifying the timing and magnitude of habitat limitations as well as the most efficient strategies for achieving conservation objectives

A General Framework for Setting Quantitative Population Objectives for Wildlife Conservation

Quantitative population objectives are necessary to successfully achieve conservation goals of secure or robust wildlife populations. However, existing methods for setting quantitative population objectives commonly require extensive species-specific population viability data, which are often unavailable or are based on estimates of historical population sizes, which may no longer represent feasible objectives. Conservation practitioners require an alternative, science-based method for setting long-term quantitative population objectives. We reviewed conservation biology literature to develop a general conceptual framework that represents conservation biology principles and identifies key milestones a population would be expected to pass in the process of becoming a recovered or robust population. We then synthesized recent research to propose general hypotheses for the orders of magnitude at which most populations would be expected to reach each milestone. The framework is structured as a hierarchy of four population sizes, ranging from very small populations at increased risk of inbreeding depression and extirpation (&lt; 1,000 adults) to large populations with minimized risk of extirpation (&gt; 50,000 adults), along with additional modifiers describing steeply declining and resilient populations. We also discuss the temporal and geographic scales at which this framework should be applied. To illustrate the application of this framework to conservation planning, we outline our use of the framework to set long-term population objectives for a multi-species regional conservation plan, and discuss additional considerations in applying this framework to other systems. This general framework provides a transparent, science-based method by which conservation practitioners and stakeholders can agree on long-term population objectives of an appropriate magnitude, particularly when the alternative approaches are not feasible. With initial population objectives determined, long-term conservation planning and implementation can get underway, while further refinement of the objectives still remains possible as the population’s response to conservation effort is monitored and new data become available

Population and Habitat Objectives for Avian Conservation in California's Central Valley Riparian Ecosystems

Riparian ecosystems provide important ecosystem services and recreational opportunities for people, and habitat for wildlife. In California’s Central Valley, government agencies and private organizations are working together to protect and restore riparian ecosystems, and the Central Valley Joint Venture provides leadership in the formulation of goals and objectives for avian conservation in riparian ecosystems. We defined a long-term conservation goal as the establishment of riparian ecosystems that provide sufficient habitat to support genetically robust, self-sustaining, and resilient bird populations. To achieve this goal, we selected a suite of 12 breeding riparian landbird focal species as indicators of the state of riparian ecosystems in each of four major Central Valley planning regions. Using recent bird survey data, we estimated that over half of the regional focal species populations are currently small (&lt; 10,000) and may be vulnerable to extirpation, and two species have steeply declining population trends. For each focal species in each region, we defined long-term (100-year) population objectives that are intended to be conservation endpoints that we expect to meet the goal of genetically robust, self-sustaining, and resilient populations. We then estimated the long-term species density and riparian restoration objectives required to achieve the long-term population objectives. To track progress toward the long-term objectives, we propose short-term (10- year) objectives, including the addition of 12,919 ha (31,923 ac) of riparian vegetation in the Central Valley (by planning region: 3,390 ha in Sacramento, 2,390 ha in Yolo–Delta, 3,386 ha in San Joaquin, and 3,753 ha in Tulare). We expect that reaching these population, density, and habitat objectives through threat abatement, habitat restoration, and habitat enhancement will result in improvements to riparian ecosystem function and resilience that will benefit other wildlife populations and the people of the Central Valley and beyond

Population and Habitat Objectives for Avian Conservation in California's Central Valley Riparian Ecosystems

Riparian ecosystems provide important ecosystem services and recreational opportunities for people, and habitat for wildlife. In California’s Central Valley, government agencies and private organizations are working together to protect and restore riparian ecosystems, and the Central Valley Joint Venture provides leadership in the formulation of goals and objectives for avian conservation in riparian ecosystems. We defined a long-term conservation goal as the establishment of riparian ecosystems that provide sufficient habitat to support genetically robust, self-sustaining, and resilient bird populations. To achieve this goal, we selected a suite of 12 breeding riparian landbird focal species as indicators of the state of riparian ecosystems in each of four major Central Valley planning regions. Using recent bird survey data, we estimated that over half of the regional focal species populations are currently small (&lt; 10,000) and may be vulnerable to extirpation, and two species have steeply declining population trends. For each focal species in each region, we defined long-term (100-year) population objectives that are intended to be conservation endpoints that we expect to meet the goal of genetically robust, self-sustaining, and resilient populations. We then estimated the long-term species density and riparian restoration objectives required to achieve the long-term population objectives. To track progress toward the long-term objectives, we propose short-term (10- year) objectives, including the addition of 12,919 ha (31,923 ac) of riparian vegetation in the Central Valley (by planning region: 3,390 ha in Sacramento, 2,390 ha in Yolo–Delta, 3,386 ha in San Joaquin, and 3,753 ha in Tulare). We expect that reaching these population, density, and habitat objectives through threat abatement, habitat restoration, and habitat enhancement will result in improvements to riparian ecosystem function and resilience that will benefit other wildlife populations and the people of the Central Valley and beyond

Population and Habitat Objectives for Avian Conservation in California's Central Valley Riparian Ecosystems

https://doi.org/10.15447/sfews.2017v15iss1art5Riparian ecosystems provide important ecosystem services and recreational opportunities for people, and habitat for wildlife. In California’s Central Valley, government agencies and private organizations are working together to protect and restore riparian ecosystems, and the Central Valley Joint Venture provides leadership in the formulation of goals and objectives for avian conservation in riparian ecosystems. We defined a long-term conservation goal as the establishment of riparian ecosystems that provide sufficient habitat to support genetically robust, self-sustaining, and resilient bird populations. To achieve this goal, we selected a suite of 12 breeding riparian landbird focal species as indicators of the state of riparian ecosystems in each of four major Central Valley planning regions. Using recent bird survey data, we estimated that over half of the regional focal species populations are currently small (&lt; 10,000) and may be vulnerable to extirpation, and two species have steeply declining population trends. For each focal species in each region, we defined long-term (100-year) population objectives that are intended to be conservation endpoints that we expect to meet the goal of genetically robust, self-sustaining, and resilient populations. We then estimated the long-term species density and riparian restoration objectives required to achieve the long-term population objectives. To track progress toward the long-term objectives, we propose short-term (10- year) objectives, including the addition of 12,919 ha (31,923 ac) of riparian vegetation in the Central Valley (by planning region: 3,390 ha in Sacramento, 2,390 ha in Yolo–Delta, 3,386 ha in San Joaquin, and 3,753 ha in Tulare). We expect that reaching these population, density, and habitat objectives through threat abatement, habitat restoration, and habitat enhancement will result in improvements to riparian ecosystem function and resilience that will benefit other wildlife populations and the people of the Central Valley and beyond.</p

Data from: Spatiotemporal patterns of duck nest density and predation risk: a multi-scale analysis of 18 years and more than 10 000 nests

Many avian species are behaviorally-plastic in selecting nest sites, and may shift to new locations or habitats following an unsuccessful breeding attempt. If there is predictable spatial variation in predation risk, the process of many individuals using prior experience to adaptively change nest sites may scale up to create shifting patterns of nest density at a population level. We used 18 years of waterfowl nesting data to assess whether there were areas of consistently high or low predation risk, and whether low-risk areas increased, and high-risk areas decreased in nest density the following year. We created kernel density maps of successful and unsuccessful nests in consecutive years and found no correlation in predation risk and no evidence for adaptive shifts, although nest density was correlated between years. We also examined between-year correlations in nest density and nest success at three smaller spatial scales: individual nesting fields (10–28 ha), 16-ha grid cells and 4-ha grid cells. Here, results were similar across all scales: we found no evidence for year-to-year correlation in nest success but found strong evidence that nest density was correlated between years, and areas of high nest success increased in nest density the following year. Prior research in this system has demonstrated that areas of high nest density have higher nest success, and taken together, our results suggest that ducks may adaptively select nest sites based on the local density of conspecifics, rather than the physical location of last year's nest. In unpredictable environments, current cues, such as the presence of active conspecific nests, may be especially useful in selecting nest sites. The cues birds use to select breeding locations and successfully avoid predators deserve continued attention, especially in systems of conservation concern

Ringelman et al. 2016 Oikos data

These are the data files used in the analysis. There are four sheets: one each for the kernel overlap, field-level correlation, 400m grid cell correlation, and 200m grid-cell correlation analysis

Movement ecology of five Afrotropical waterfowl species from Malawi, Mali and Nigeria §

Habitat availability for Afrotropical waterbirds is highly dynamic with unpredictable rainfall patterns and ephemeral wetlands resulting in diverse movement strategies among different species. Movement strategies among waterfowl encompass resident, regional and intercontinental migrants, but little quantitative information exists on their specific movement patterns. We studied the movement ecology of five Afrotropical waterfowl species marked with satellite transmitters in Malawi, Mali and Nigeria. Resident species, including White-faced Whistling Ducks Dendrocygna viduata, Fulvous Whistling Ducks Dendrocygna bicolor and Spur-winged Geese Plectropterus gambensis, remained sedentary during the rainy season and only flew limited distances during other months. In contrast, Knob-billed Ducks Sarkidiornis melanotos made short regional movements &gt;50 km in all months and showed little site fidelity to previously used habitats in subsequent years. Garganey Anas quequedula followed an intercontinental strategy and made long-distance jumps across the Sahara and Mediterranean to their Eurasian breeding grounds. Most species flew farthest during the dry season, as mean daily movements varied from 1.5 to 14.2 km and was greatest in the winter months (January–March). Total distance moved varied from 9.5 km for White-faced Whistling Ducks (October–December) to 45.6 km for Knob-billed Ducks (April–June). Nomadic behaviour by Knob-billed Ducks was evidenced by long exploratory flights, but small mean daily movements suggested that they were relying on previous experience. Improving our understanding of these movement strategies increases our ability to assess connectivity of wetland resources that support waterfowl throughout their annual cycle and focuses conservation efforts on their most important habitats.Keywords: migration, nomadism, Sahel, satellite telemetry, sub-Saharan, waterfowl, wetland