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Managing for the effects of climate change on species whose populations are currently imperiled requires detailed knowledge of the relationship between their demographic rates and climate variables. We sought this information for the West Coast breeding population of snowy plover (Charadrius nivosus), which was federally listed as threatened in 1993 due to substantial declines in the numbers of plovers breeding along the coast and in the number of sites occupied for breeding. Snowy plovers employ a serially polygamous breeding system in which the male typically tends chicks to independence. This unusual breeding system is favored by male‐biased sex ratios in local populations. As part of a multispecies study of the effect of climate change on population growth, we used mark–capture models to examine climate drivers of adult survival for 1219 snowy plovers banded at Monterey Bay over 38 years and known to overwinter on the surrounding north‐central California outer coast. Nonclimate variables, including sex and unmeasured annual mortality risks (e.g., predator abundance), were the primary factors affecting adult survival. However, there is evidence that cold weather, particularly extended cold snaps with daily low temperatures below 2°C and daily high temperatures below 10°C, decreases overwinter survival. Exceptionally cold winters had a particularly strong effect on adult female plovers, contributing to the male‐biased adult sex ratios. Future winter climate on the north‐central California coast is projected to be generally warmer with fewer and shorter cold snaps. Reduced mortality from cold winter weather may mitigate other threats faced by plovers, such as anthropogenically enhanced predator populations, habitat loss, and accelerated sea level rise, while altering the adult sex ratio and potentially shifting the evolutionary landscape maintaining the plover's unusual breeding system. [ABSTRACT FROM AUTHOR]

Programs that incentivize private landowners to create habitats that offset losses due to conversion and climate change are increasingly being used to bolster sensitive wildlife populations. In the Central Valley of California, shorebird habitat incentive programs pay landowners to create additional habitat during the non‐breeding season by flooding their fields. However, it remains unclear how successful these programs have been in supporting baseline shorebird population needs or meeting established population goals, particularly in the face of changing environmental conditions. To address these questions, we used bioenergetics modeling to estimate shorebird food energy needs over four consecutive years that had the highest annual mean air temperatures ever recorded in California, and included years of extreme drought, as well as the second wettest winter on record. Our objectives were to (1) characterize annual variability in the timing and magnitude of shorebird food energy shortfalls, (2) estimate the contributions that incentive programs made to meeting these needs, and (3) develop recommendations for implementation of future habitat programs to advance shorebird conservation in the region. Overall, we found a high level of consistency in the timing and magnitude of habitat shortfalls, especially in fall, despite large differences in annual rainfall, a result that was unexpected, but that emphasizes how highly managed the hydrological system is in the Central Valley. We also found that the magnitude of both fall and spring energy shortfalls increased, relative to recent (2007–2014) estimates, perhaps due to aberrantly warm conditions. Incentive programs implemented to provide supplemental habitat were somewhat effective in reducing shortfalls for the assumed baseline population, but there were consistent unmet habitat needs when there were not enough shallow open water foraging areas available. Strategies to offset these remaining food energy deficits include scaling up habitat investments, adjusting the timing of habitat programs to better match the migration patterns of the birds, and adapting programs to new geographies. To the extent that there is variability in annual habitat need we recommend implementing a dynamic conservation approach. This involves scaling the amount of additional habitat created to match the shifting needs of the birds to maximize return on investment. [ABSTRACT FROM AUTHOR]

El Nin˜ o events elevate water levels, change wave direction and storm frequency, and provide an analogy to the likely impacts of climate change. Elevated sea levels intensify coastal erosion impacts affecting not only oceanfront property and recreational users, but also habitats and species that depend on the coast. This study examines physical and ecological responses to and recovery from the extreme 1997–98El Nin˜ o along beaches of Isla Vista, California, a stretch of coastline dominated by unidirectional alongshore sediment transport. Using topographic light detection and ranging (LIDAR), physical measurements, and biological surveys we quantify physical changes and assess ecological responses. We quantify short-term reductions in beach widths (.60%) and sand volumes (,80%). Although dune-backed beaches lost greater sand volumes, bluff-backed shorelines lost greater percentages of beach width. Four erosion hot spots were identified consistent with a pattern of beach reorientations. Macrophyte wrack abundance, a primary food for sandy beach ecosystems, was significantly correlated with dry sand beach width. Macroinvertebrate biomass was reduced and a decline in mean size of individuals persisted for several species. Abundance and species richness of shorebirds were lower during the El Nin˜ o. Beach segments and reorientations recovered at different times, on the basis of littoral drift direction, shoreline orientation, and wave exposure. The reorientation at the updrift beach impounded sand for .3 years after the El Nin˜ o, catalysing an erosion wave that propagated downdrift affecting downcoast beaches. Recovery of the updrift beach led to the widest beach widths shown in the historic record, whereas the downdrift beach underwent continued erosion .6 years after the El Nin˜ o. Recovery of wrack abundance and shore birds to pre-El Nin˜ o levels took .3 years. Reductions in biomass and mean size of invertebrates were detected 2 years after the event. Recovery time lines provide information for coastal managers evaluating impacts and timing of erosion mitigation alternatives. [ABSTRACT FROM AUTHOR]

The article discusses a study which investigated breeding stage influences space use of female American avocets in San Francisco Bay, California. The researchers used Hawth's Tools for ArcGIS to calculate the liner distance between consecutive locations for radio-marked avocets. It was found that linear movements, home ranges, core areas, and distances from nest were greater in the post-breeding and pre-incubation stages than during the incubation and brood-rearing stages. A map is presented showing dominant habitat types.

Juvenile survival and dispersal rates are important demographic parameters in predicting the viability of avian populations, but estimates are seldom available because mortality is usually confounded with permanent natal dispersal in analyses of live-encounter data. We used the Barker model for combined captures, recoveries, and resightings to estimate juvenile survival in fledgling Snowy Plover (Charadrius alexandrinus) for the 6.5-to-10.5-month period between fledging at 28 days and 1 April the following year, on the central California coast, for a 16-year period, 1984-1999. By using a large body of year-round sighting data from throughout the species' Pacific-coast range, we estimated true survival and quantified natal dispersal rates and distances. Juvenile survival estimates varied annually between 0.283 ± 0.028 (mean ± SE) and 0.575 ± 0.061 with no trend over the study, and paralleled higher adult survival in our most parsimonious models. In comparison, annual survival of banded chicks from hatching to fledging at age 28 days was 0.285-0.483 (x̄ = 0.382 ± 0.014 SE) for those 16 years. Males were more likely to disperse from Monterey Bay for winter and females were more likely to disperse for breeding. Dispersal distances to breeding sites were usually within 10 km of natal sites (64%) and seldom >50 km (16%). The present study provides the first estimate of true survival for a juvenile shorebird and new information on survival and dispersal rates that will be useful for modeling Snowy Plover population viability. Studies of local winter residents, focused on predator pressure and weather conditions, could further advance our understanding of factors determining Snowy Plover survival. [ABSTRACT FROM AUTHOR]

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., (© 2018 by the Ecological Society of America.)

Organochlorines, metals, and trace elements were measured in liver, kidney, or wholebody tissues of canvasbacks (Aythya valisineria), lesser scaups (A. affinis), and greater scaups (A. marila) collected from San Francisco Bay and three coastal areas of California during the winter of 1986--1987. Potentially toxic concentrations of mercury (mean =/<10.4 mu g/g, dry weight) and selenium (mean =/<32.7 mu g/g, dryweight) were found in livers of scaups; and canvasbacks from severalSan Francisco Bay sites. These elements varied spatially, temporally, and between species, with the highest concentrations found in late winter. Mean concentrations of mercury, selenium, and cadmium were generally higher in scaups than in canvasbacks. Of all the organochlorines included in the analyses, only p,p'-DDE and total PCBs were detected in all samples in this study. Mean whole-body concentrations of DDE and PCBs from San Francisco Bay ducks collected in late winter varied spatially and between species, but the concentrations were not considered toxic. Causes for inter-specific differences arc unclear, but may be attributable to differences in diet, movement, or physiology. [ABSTRACT FROM AUTHOR]