Shorebird Habitat Research Articles

Smartphone-Based Distributed Data Collection Enables Rapid Assessment of Shorebird Habitat Suitability.

Understanding and managing dynamic coastal landscapes for beach-dependent species requires biological and geological data across the range of relevant environments and habitats. It is difficult to acquire such information; data often have limited focus due to resource constraints, are collected by non-specialists, or lack observational uniformity. We developed an open-source smartphone application called iPlover that addresses these difficulties in collecting biogeomorphic information at piping plover (Charadrius melodus) nest sites on coastal beaches. This paper describes iPlover development and evaluates data quality and utility following two years of collection (n = 1799 data points over 1500 km of coast between Maine and North Carolina, USA). We found strong agreement between field user and expert assessments and high model skill when data were used for habitat suitability prediction. Methods used here to develop and deploy a distributed data collection system have broad applicability to interdisciplinary environmental monitoring and modeling.

Mapping foraging habitat for migratory shorebirds in their Australian non-breeding grounds and prioritising sites for conservation and management

Shorebird populations are declining worldwide as a result of the loss of the intertidal habitats upon which they depend. Conservation status is particularly dire for shorebirds on the East Asian–Australasian Flyway. While the flyway transects many international boundaries and involves numerous bilateral conservation agreements, management of remaining habitat at a local scale is imperative to conserving these species. Coastal habitat is affected by multiple anthropogenic stressors, including loss and degradation due to increasing demand for coastal land. In Australia, migration coincides with the summer holiday season when shorebirds are significantly impacted by human disturbance. Managers are frequently required to make trade-offs between wildlife conservation and anthropogenic land uses and when specific quantitative shorebird habitat data and mapping are absent, human interests will naturally take precedence. This paper demonstrates a method for mapping and prioritising management of shorebird non-breeding habitat using an Australian coastal site, the Richmond River estuary. Foraging habitat was surveyed and mapped using GIS with a range of attributes including habitat types, foraging values, disturbance levels and specific foraging distribution of each species. The results highlighted several important foraging areas that were impacted by disturbance and would require intervening management actions to reduce impacts on shorebirds. The GIS data created provide local managers with an effective tool to consider shorebird habitat in the decision-making process. This method could be replicated at other important shorebird habitat sites, leading to enhanced conservation of these declining species.

Continental-scale decreases in shorebird populations in Australia

Decreases in shorebird populations are increasingly evident worldwide, especially in the East Asian—Australasian Flyway (EAAF). To arrest these declines, it is important to understand the scale of both the problem and the solutions. We analysed an expansive Australian citizen-science dataset, spanning the period 1973 to 2014, to explore factors related to differences in trends among shorebird populations in wetlands throughout Australia. Of seven resident Australian shorebird species, the four inland species exhibited continental decreases, whereas the three coastal species did not. Decreases in inland resident shorebirds were related to changes in availability of water at non-tidal wetlands, suggesting that degradation of wetlands in Australia's interior is playing a role in these declines. For migratory shorebirds, the analyses revealed continental decreases in abundance in 12 of 19 species, and decreases in 17 of 19 in the southern half of Australia over the past 15 years. Many trends were strongly associated with continental gradients in latitude or longitude, suggesting some large-scale patterns in the decreases, with steeper declines often evident in southern Australia. After accounting for this effect, local variables did not explain variation in migratory shorebird trends between sites. Our results are consistent with other studies indicating that decreases in migratory shorebird populations in the EAAF are most likely being driven primarily by factors outside Australia. This reinforces the need for urgent overseas conservation actions. However, substantially heterogeneous trends within Australia, combined with declines of inland resident shorebirds indicate effective management of Australian shorebird habitat remains important.

Numerical Response of Migratory Shorebirds to Prey Distribution in a Large Temperate Arid Wetland, China.

Wuliangsuhai Lake provides important breeding and stopover habitats for shorebirds. The health of this wetland ecosystem is rapidly deteriorating due to eutrophication and water pollution and environmental management is urgently needed. To explore the connections among ecosystem health, prey density, and shorebird populations, we conducted surveys of both the benthic macroinvertebrates and shorebirds in the shorebird habitat of the wetland during the 2011 autumn migration season. The abundance of both shorebirds and benthic macroinvertebrates varied significantly in both space and time. Our data showed a clear association between shorebird populations and the density of benthic macroinvertebrates, which explained 53.63% of the variation in shorebird abundance. The prey density was strongly affected by environmental factors, including water and sediment quality. Chironomidae were mainly found at sites with higher total phosphorus, but with lower sediment concentrations of Cu. Lymnaeidae were mainly found at sites with a higher pH, lower salinity, and lower concentrations of total phosphorus and Cu. Habitats with very high concentrations of total phosphorus, heavy metals, or salinity were not suitable for benthic macroinvertebrates. Our findings suggest that the reductions of nutrient and heavy metal loadings are crucial in maintaining the ecological function of Wuliangsuhai as a stopover habitat for migratory shorebirds.

Endangered species management and ecosystem restoration: finding the common ground

Casazza, M. L., C. T. Overton, T.-V. D. Bui, J. M. Hull, J. D. Albertson, V. K. Bloom, S. Bobzien, J. McBroom, M. Latta, P. Olofson, T. M. Rohmer, S. Schwarzbach, D. R. Strong, E. Grijalva, J. K. Wood, S. M. Skalos, and J. Takekawa. 2016. Endangered species management and ecosystem restoration: finding the common ground. Ecology and Society 21(1):19.http://dx.doi.org/10.5751/ES-08134-210119

Testing assumptions for conservation of migratory shorebirds and coastal managed wetlands

Managed wetlands provide critical foraging and roosting habitats for shorebirds during migration; therefore, ensuring their availability is a priority action in shorebird conservation plans. Contemporary shorebird conservation plans rely on a number of assumptions about shorebird prey resources and migratory behavior to determine stopover habitat requirements. For example, the US Shorebird Conservation Plan for the Southeast-Caribbean region assumes that average benthic invertebrate biomass in foraging habitats is 2.4 g dry mass m−2 and that the dominant prey item of shorebirds in the region is Chironomid larvae. For effective conservation and management, it is important to test working assumptions and update predictive models that are used to estimate habitat requirements. We surveyed migratory shorebirds and sampled the benthic invertebrate community in coastal managed wetlands of South Carolina. We sampled invertebrates at three points in time representing early, middle, and late stages of spring migration, and concurrently surveyed shorebird stopover populations at approximately 7-day intervals throughout migration. We used analysis of variance by ranks to test for temporal variation in invertebrate biomass and density, and we used a model based approach (linear mixed model and Monte Carlo simulation) to estimate mean biomass and density. There was little evidence of a temporal variation in biomass or density during the course of spring shorebird migration, suggesting that shorebirds did not deplete invertebrate prey resources at our site. Estimated biomass was 1.47 g dry mass m−2 (95 % credible interval 0.13–3.55), approximately 39 % lower than values used in the regional shorebird conservation plan. An additional 4728 ha (a 63 % increase) would be required if habitat objectives were derived from biomass levels observed in our study. Polychaetes, especially Laeonereis culveri (2569 individuals m−2), were the most abundant prey in foraging habitats at our site. Polychaetes have lower caloric content than levels assumed in the regional plan; when lower caloric content and lower biomass levels are used to determine habitat objectives, an additional 6395 ha would be required (86 % increase). Shorebird conservation and management plans would benefit from considering the uncertainty in parameters used to derive habitat objectives, especially biomass and caloric content of prey resources. Iterative testing of models that are specific to the planning region will provide rapid advances for management and conservation of migratory shorebirds and coastal managed wetlands.

The ecology and economics of shorebird conservation in a tropical human‐modified landscape

Summary Rapid and extensive land‐use change in intertidal foraging habitat and coastal roosting habitat is thought to be driving major population declines of shorebirds migrating through the East Asian–Australasian Flyway. Along the Inner Gulf of Thailand, a critical stopover and wintering ground for these birds, artificial wetlands (salt pans and aquaculture ponds) have replaced much of the natural coastal ecosystem. We conducted a two‐part study to (i) assess the importance of salt pans and semi‐traditional aquaculture ponds to shorebirds and (ii) understand the economic forces that drive land‐use change in this region by interviewing salt pan and aquaculture operators. Salt pans provide important roost habitat, particularly for shorter‐legged birds, which are less able to utilize aquaculture ponds due to their greater depth. Moreover, three focal shorebird species foraged extensively in salt pans and semi‐traditional aquaculture ponds, even when intertidal mudflats were exposed, suggesting that artificial wetlands could buffer against the impacts of degraded intertidal foraging areas for some shorebird species. Economic profits from salt production and semi‐traditional aquaculture are similar. Risks to investment and per capita profitability are key factors in determining whether to convert land from one use (e.g. salt pan) to the other (aquaculture). Synthesis and applications. Salt pans provide an important resource to migrating shorebirds. As development pressures increase, operators may need financial incentives if salt pans are to be maintained over large areas. Although semi‐traditional aquaculture is used less by shorebirds, drained ponds provide opportunities to roost and forage. Semi‐traditional aquaculture operators should drain their ponds regularly to provide supplementary habitat for shorebirds. Use of nets and pond liners should be discouraged in both systems. Optimizing aquaculture pond and salt pan management for shorebirds could provide a more pragmatic, cost‐effective and geographically extensive solution to conserving these birds than protected areas alone.

Geomorphologic dynamics and maintenance following mudflat, creek and pond formation in an estuarine mangrove wetland

Mudflats, creeks and ponds serve as critical habitat for shorebirds and fish in subtropical estuarine wetlands. A wetland restoration project was launched to remove partial mangrove trees from a predefined area and form a mudflat patch. A creek-pond-combo (CPC) construction project was also conducted in the Shezi wetland area along the Danshuei River. Long-term measurements were performed to test for geomorphologic responses and related habitat changes. The dynamic topography revealed significant patterns of sediment deposition, with the highest deposition rates found in the CPC habitat area. The sediment trap efficiency of the CPC was roughly seven-fold higher than that of the mudflat area. The CPC area gradually evolved into a mudflat habitat area through processes of sediment deposition and was significantly reduced in size and more shallow after typhoon events. The shrinking phenomenon occurred prior to deposition and at a faster rate. CPC construction is recommended every two years, and the related maintenance costs are estimated to be approximately 1,500 US dollars per year. The findings of this study indicate that long-term investments should be made to maintain CPC areas in estuarine mangrove wetlands.

Adapting environmental management to uncertain but inevitable change.

Implementation of adaptation actions to protect biodiversity is limited by uncertainty about the future. One reason for this is the fear of making the wrong decisions caused by the myriad future scenarios presented to decision-makers. We propose an adaptive management (AM) method for optimally managing a population under uncertain and changing habitat conditions. Our approach incorporates multiple future scenarios and continually learns the best management strategy from observations, even as conditions change. We demonstrate the performance of our AM approach by applying it to the spatial management of migratory shorebird habitats on the East Asian-Australasian flyway, predicted to be severely impacted by future sea-level rise. By accounting for non-stationary dynamics, our solution protects 25,000 more birds per year than the current best stationary approach. Our approach can be applied to many ecological systems that require efficient adaptation strategies for an uncertain future.

Protecting stopover habitat for migratory shorebirds in East Asia

Many migratory species depend on staging sites at which they refuel while on migration, and effective protection of such habitats is crucial to their conservation. Here we investigate the extent to which protected areas cover and ameliorate loss of tidal flats in East Asia, the key staging habitat for threatened and declining shorebirds migrating through the East Asian–Australasian Flyway. We discover rapid losses of the tidal flat ecosystem both inside (−0.42 % year−1) and outside (−0.89 % year−1) protected areas. In China, tidal flats are well represented within protected areas (22.9 % of current tidal flats occur within protected areas), but habitat loss continued despite protection (−0.55 % year−1 inside, −0.97 % year−1 outside). By contrast, in South Korea, where 12.1 % of remaining tidal flat is in protected areas, the rate of habitat loss outside protected areas was the highest in our study region (−1.83 % year−1), yet inside protected areas there was tidal flat aggradation (+1.13 % year−1), indicating either that protected area placement is biased away from vulnerable habitats, or protected areas are highly effective in South Korea. Tidal flats across our study area were lost most rapidly in internationally important sites for migratory shorebirds (−1.66 % year−1), suggesting that transformative land use change of coastal areas is occurring disproportionately in regions that are important for migratory birds. We urge (1) improved management of existing protected areas in East Asia, particularly in China, (2) targeted designation of new protected areas in sites crucial for supporting migratory birds and (3) integrated decision-making that simultaneously plans for coastal development and coastal conservation.

A Potential Role of Shrimp Farms for the Conservation of Nearctic Shorebird Populations

Shrimp aquaculture farms have greatly expanded at tropical areas worldwide, especially during the past three decades. One of the main core areas of this expansion was the northwestern coast of Mexico, prompting conservation concern for the shorebird populations that spend the nonbreeding period (October to March) in the region. We conducted a series of counts and behavioral observations to evaluate the importance of a shrimp farm as foraging habitat for shorebirds, relative to adjacent intertidal areas, during and after the shrimp harvest period at a tropical wetland in Sinaloa, Mexico, 2012 and 2013. Overall, low-tide counts within the entire wetland had an average of 3,168 ± 605 (SE) shorebirds during the shrimp harvest period (October–November) and subsequently dropped to 1,408 ± 373 birds following harvest (December to January), when shrimp ponds were emptied and foraging opportunities were reduced. The proportion of counts at the shrimp farm relative to total counts over the entire wetland ranged from 10 to 80 % for different shorebird species and dropped to 0 to 10 % in the postharvest period. During the harvesting period, black-necked stilt, American avocet, willet, and whimbrel selected shrimp ponds over intertidal areas to forage during low tide, while marbled godwit, western sandpiper, and dowitchers did not. The proportion of shorebirds observed feeding at the shrimp farm ranged between 60 and 90 % for most species and did not differ between low- and high-tide counts. These results suggest that shrimp farms can provide ephemeral but important complementary foraging areas for shorebirds, and appropriate management of existing farms may aid in conservation efforts for these species.

Optimal management of a multispecies shorebird flyway under sea-level rise.

Every year, millions of migratory shorebirds fly through the East Asian-Australasian Flyway between their arctic breeding grounds and Australasia. This flyway includes numerous coastal wetlands in Asia and the Pacific that are used as stopover sites where birds rest and feed. Loss of a few important stopover sites through sea-level rise (SLR) could cause sudden population declines. We formulated and solved mathematically the problem of how to identify the most important stopover sites to minimize losses of bird populations across flyways by conserving land that facilitates upshore shifts of tidal flats in response to SLR. To guide conservation investment that minimizes losses of migratory bird populations during migration, we developed a spatially explicit flyway model coupled with a maximum flow algorithm. Migratory routes of 10 shorebird taxa were modeled in a graph theoretic framework by representing clusters of important wetlands as nodes and the number of birds flying between 2 nodes as edges. We also evaluated several resource allocation algorithms that required only partial information on flyway connectivity (node strategy, based on the impacts of SLR at nodes; habitat strategy, based on habitat change at sites; population strategy, based on population change at sites; and random investment). The resource allocation algorithms based on flyway information performed on average 15% better than simpler allocations based on patterns of habitat loss or local bird counts. The Yellow Sea region stood out as the most important priority for effective conservation of migratory shorebirds, but investment in this area alone will not ensure the persistence of species across the flyway. The spatial distribution of conservation investments differed enormously according to the severity of SLR and whether information about flyway connectivity was used to guide the prioritizations. With the rapid ongoing loss of coastal wetlands globally, our method provides insight into efficient conservation planning for migratory species.

Sediment-benthos relationships as a tool to assist in conservation practices in a coastal lagoon subjected to sediment change

This study explores the relation between sediment composition and intertidal macrobenthos populations in the Zwin nature reserve (Belgium and The Netherlands), a tidal lagoon that is included in the Ramsar list of wetlands of international importance and has been designated as Natura 2000 area, among others due to its function as wintering habitat for shorebirds that feed upon macrobenthic invertebrates. Species response models show highest biomass of these prey species in organically enriched cohesive sediments and a distinct decline in probability of occurrence for most species in coarse sediments. Further, the biomass of macrobenthos declined between 2003 and 2010 in the extensive low intertidal inlet channel concurrent with the coarsening of the sediment over time in this hydrodynamically stressed habitat. In contrast, macrobenthos biomass increased in a sheltered shallow intertidal habitat that acted as a catchment area for finer sediments, therefore facilitating the succession towards a higher elevated habitat with salt marsh vegetation establishment. Hence, spatio-temporal sediment dynamics decreased site quality for intertidal predators due to a reduction in feeding areas over time, and a change in physical sediment properties that alter the macrobenthos species occurrence and population biomass. This study thus illustrates that sediment transport dynamics may affect the functioning of coastal shallow soft-sediment habitats, like coastal lagoons. The presented macrobenthos species response models provide a tool to assist in management actions that enable the conservation of cohesive low intertidal habitats that provide a high food supply to shorebirds, fish and macrocrustaceans.

Can Human-made Saltpans Represent an Alternative Habitat for Shorebirds? Implications for a Predictable Loss of Estuarine Sediment Flats

Estuarine areas worldwide are under intense pressure due to human activities such as upstream dam building. Shorebirds strongly depend on estuarine intertidal flats during migration and wintering periods and so are particularly vulnerable to such impacts, whose magnitude will depend on the availability of alternative feeding habitats. In this study we analyze if man-made saltpans can represent an alternative habitat for wintering and migrating shorebirds in the Guadiana estuary, a wetland that is already experiencing environmental changes due to the building of the Alqueva reservoir, the largest in Western Europe. We compared the use of mudflats and saltpans as feeding areas by several shorebird species before the construction of the dam. A dataset with 26 years of counts data was also analyzed in order to detect any long-term trend in shorebirds abundance. We concluded that saltpans, in particular the fully mechanized, can be used as an alternative habitat by larger species during winter and southward migration, thus playing a major role in minimizing the possible effects of sediment loss due to dam building. In contrast, smaller species were particularly dependent on mudflats to feed. A significant change in population trends, from positive to negative, was detected for two species. Although we still have no evidence that this is directly linked to dam building, this result and documented changes that limit primary productivity justifies the implementation of a long-term monitoring scheme of shorebird populations in this estuary. We also reinforce the need to manage the saltpans as key habitats for shorebirds.

Alteration of wetland hydrology in coastal lagoons: Implications for shorebird conservation and wetland restoration at a Ramsar site in Sri Lanka

Many of the world’s lagoons and estuaries, representing the most important habitat for shorebirds, are increasingly degraded, often associated with dramatic declines in shorebirds, particularly in Asia. We investigated effects of hydrology on shorebird communities of two coastal lagoons of a Ramsar site in south-east Sri Lanka. One of the lagoons (Bundala) experienced natural water level fluctuations, while the other (Embilikala) had high stable water levels (>10cm), maintained by inflows from irrigated agriculture. These inflows dramatically affected composition and abundance of shorebird communities and their prey. Tactile and visual foraging shorebirds were consistently more abundant on Bundala than Embilikala lagoon. Their feeding efficiency was significantly (50%) higher on Bundala, where large (500μm) benthic prey were more abundant than on Embilikala. Contrastingly, small (60μm) planktonic prey dominated the hydrologically stable Embilikala lagoon where pelagic foraging shorebird species dominated the shorebird community. On both lagoons, visual and tactile species foraged predominantly in shallow water (1–10cm). Pelagic shorebirds also foraged in water depths >10cm but 20% less efficiently than in shallower water. Effective shorebird conservation depends on reducing anthropogenic impacts that detrimentally affect functional processes and habitat value. The detrimental effect of altered hydrology on Embilikala lagoon could be reversed by diverting drainage water. Re-establishing a natural hydroperiod, would increase the productivity of the lagoon for foraging shorebirds. Restoration of shorebird habitat on this Ramsar site could also improve other ecosystem services such as fisheries and tourism. Changes to the hydrology of coastal lagoons elsewhere may be similarly affected.

The Habitat Use and Home Range Analysis of Dunlin (Calidris alpina) in Chongming Dongtan, China and their Conservation Implications

Natural coastal wetlands are important habitats for shorebirds while flooded agricultural croplands, may also be useful habitats. Shorebirds in East Asia utilize an often highly developed coastal landscape, which may be dissected by seawalls with intertidal flats on the seaward side, and aquaculture ponds and agricultural croplands on the landward side. Little is known about the value of aquaculture ponds to shorebirds. We investigated the habitat use, preference and home range of wintering Dunlin (Calidris alpina) in Chongming Dongtan, east China, through radio tracking and field observations in 2006–2007. Our results indicated that Dunlins preferred tidal flats, avoided agricultural croplands, and used aquaculture ponds in proportion to their availability. The probability of Dunlin usage of aquacultural ponds decreased with increasing size of unflooded area in the aquaculture ponds. Dunlins foraging in aquaculture ponds had lower feeding success rate than those in tidal flats. Thus, tidal flats may provide important foraging habitats for wintering Dunlins, while aquaculture ponds may provide alternative roosting and supplemental foraging habitat. Conserving the natural wetlands on tidal flats is vital for shorebird conservation in East Asia but at the same time, the aquaculture ponds also could play an important role if managed properly.

Room to move? Threatened shorebird habitat in the path of sea level rise—dynamic beaches, multiple users, and mixed ownership: a case study from Rhode Island, USA

Accelerated sea level rise (slr) is expected to transform vulnerable Atlantic coastal habitats in the United States during this century. Low-elevation sandy beaches, important nesting habitat for the continued recovery of the federally threatened piping plover (Charadrius melodus) in Rhode Island, are especially vulnerable. These beaches, under a mix of private and public ownership, exist in a heterogeneous landscape of dunes, rocky headlands, salt ponds, and heavily developed areas. Understanding the extent to which piping plover nesting beaches can retreat landward under projected slr is important for prioritizing future conservation actions across multiple jurisdictions. This research examines habitat change in response to slr (0.5, 1.0, and 1.5 m) under stationary and migration beach responses and whether development blocks habitat migration for five productive piping plover nesting beaches. We found that under the stationary habitat model, all beaches lose area under all slr scenarios. For the habitat migration model, future habitat availability differs by beach depending on elevation, landward topography, and presence of development. However, across the majority of beach area, piping plover habitat will be able to migrate landward if unconstrained by future development. A coalition of public and private stakeholders already supports management efforts to help ensure plover population recovery in the area. With emerging habitat change prediction tools, these stakeholders and other partners can engage in innovative, local-level planning needed to protect wildlife habitat and commercial, residential, and infrastructure assets from sea level rise.

Use of Aquaculture Ponds and Other Habitats by Autumn Migrating Shorebirds Along the Lower Mississippi River

Populations of many shorebird species are declining; habitat loss and degradation are among the leading causes for these declines. Shorebirds use a variety of habitats along interior migratory routes including managed moist soil units, natural wetlands, sandbars, and agricultural lands such as harvested rice fields. Less well known is shorebird use of freshwater aquaculture facilities, such as commercial cat- and crayfish ponds. We compared shorebird habitat use at drained aquaculture ponds, moist soil units, agricultural areas, sandbars and other natural habitat, and a sewage treatment facility in the in the lower Mississippi River Alluvial Valley (LMAV) during autumn 2009. Six species: Least Sandpiper (Calidris minutilla), Killdeer (Charadrius vociferous), Semipalmated Sandpiper (Calidris pusilla), Pectoral Sandpiper (C. melanotos), Black-necked Stilt (Himantopus himantopus), and Lesser Yellowlegs (Tringa flavipes), accounted for 92% of the 31,165 individuals observed. Sewage settling lagoons (83.4, 95% confidence interval [CI] 25.3-141.5 birds/ha), drained aquaculture ponds (33.5, 95% CI 22.4-44.6 birds/ha), and managed moist soil units on public lands (15.7, CI 11.2-20.3 birds/ha) had the highest estimated densities of shorebirds. The estimated 1,100ha of drained aquaculture ponds available during autumn 2009 provided over half of the estimated requirement of 2,000ha by the LMAV Joint Venture working group. However, because of the decline in the aquaculture industry, autumn shorebird habitats in the LMAV may be limited in the near future. Recognition of the current aquaculture habitat trends will be important to the future management activities of federal and state agencies. Should these aquaculture habitat trends continue, there may be a need for wildlife biologists to investigate other habitats that can be managed to offset the current and expected loss of aquaculture acreages. This study illustrates the potential for freshwater aquaculture to provide habitat for a taxa at risk. With the rapid growth of aquaculture worldwide, the practices of this industry deserve attention to identify benefits as well as risks to wildlife.

Modeling water management scenarios for the Cienega de Santa Clara, an anthropogenic coastal desert wetland system, based on inflow volumes and salinities

The Cienega de Santa Clara in the Colorado River Delta, Mexico is a self-designed wetland system fed since 1977 by brackish groundwater diverted from the U.S. to Mexico. The vegetated upper portion of the Cienega provides habitat for endangered Yuma-Clappers rails and other marsh birds and fulfills other ecological functions. Outflow water pools in the Santa Clara Slough south of the Cienega and provides habitat for migratory shorebirds. Conditions in the Cienega and Santa Clara Slough could be altered by operation of the Yuma Desalting Plant (YDP), which will divert water from the Cienega and replace it with brine water resulting from the desalting process. Our objective was to integrate water budget components into models predicting the extent of the dominant vegetation (southern cattail, Typha domingensis Pers.) in the marsh and the area of the outflow pool below the marsh in response to different operating scenarios for the YDP. The models are intended to serve as tools for resource managers charged with maintaining this wetland complex. Unlike many wetland water budget models, this one explicitly takes into account salinity as a factor in the water budget. We modeled inflow rates ranging from 1 to 6m3s−1 and inflow salinities ranging from 0 to 6gL−1 Total Dissolved Solids. The model indicates that if the inflow rate is reduced below the current 4–5m3s−1 the vegetated area of the Cienega would decrease in proportion, as would the area of the outflow pool in the Santa Clara Slough. Increases in salinity will also reduce the vegetated area due to the low salt tolerance of T. domingensis. In winter about 90% of inflow water exits the Cienega into the Santa Clara Slough due to low evapotranspiration, and on an annual basis 70% of inflows exit into the Santa Clara Slough. These flushing flows maintain the salt balance in the Cienega. The Santa Clara Slough is periodically flushed by spring tides, making this a sustainable, open wetland system in its present state.

Foraging Habitat for Shorebirds in Southeastern Missouri and its Predicted Future Availability

Water management to protect agriculture in allu- vial floodplains often conflicts with wildlife use of seasonal floodwater. Such is the case along the Mississippi River in southeastern Missouri where migrating shorebirds forage in shallow-flooded fields. I estimated the current availability of habitat for foraging shorebirds within the New Madrid and St. Johns Basins based on daily river elevations (1943- 2009), under assumptions that shorebirds forage in open habitat with water depth <15 cm and use mudflats for 3 days after exposure. The area of shorebird foraging habitat, based on replicated 50-year random samples, averaged 975 ha per day during spring and 33 ha per day during fall. Adjustments to account for habitat quality associated with different water depths, duration of mudflat exposure, intra- seasonal availability, and state of agricultural crops, indicat- ed the equivalent of 494 ha daily of optimal habitat during spring and 11 ha during fall. Proposed levees and pumps to protect cropland would reduce shorebird foraging habitat by 80 %: to 211 ha (108 optimal ha) per day during spring and 9 ha (<3 optimal ha) per day during fall. Alternative water management that allows natural flooding below a pre- scribed elevation would retain nearly all existing shore- bird foraging habitat during fall and about 60 % of extant habitat during spring.