Search

Species of conservation concern often receive intensive management to improve vital rates and facilitate recovery. Piping plovers (Charadrius melodus) are federally listed in the United States and concerns over nest depredation have prompted widespread use of plover‐permeable predator exclosures placed around nests (0.5–2‐m radius). While effectiveness of exclosures for improving nest survival has been demonstrated, concerns remain about decreased chick survival (through predator cueing or density‐dependent processes) or increased vulnerability of adults to predation (ambush as adult leaves exclosure). Either one of these concerns could demographically outweigh the benefits of increased nest survival. During 2014–2016, we conducted an experiment designed to evaluate survival of uniquely identified nests (n = 418), chicks (n = 453), and adults (n = 367) at wetlands across the Northern Great Plains, USA. We assigned wetlands (n2014 = 26, n2015 = 28, n2016 = 25) into 2 groups: wetlands in which half of the nests received exclosures and wetlands in which none of the nests received exclosures. Exclosed nests had greater cumulative survival (0.73 [85% CI = 0.70–0.77]) than unexclosed nests at treatment wetlands (0.58 [0.54–0.62]) or unexclosed nests at control wetlands (0.52 [0.49–0.56]). Survival to fledging was highest for chicks hatched from exclosed nests (0.51 [0.47–0.56]), and similar between chicks hatched from unexclosed nests at treatment (0.34 [0.30–0.39]) and control (0.37 [0.32–0.42]) wetlands. Cumulative survival of adults during incubation varied by exclosure status, but adults associated with exclosed nests (0.90 [0.88–0.93]) and unexclosed nests at treatment wetlands (0.89 [0.86–0.92]) had greater survival than those associated with unexclosed nests at control wetlands (0.75 [0.64–0.84]). Adult annual survival rates varied by year (0.79–0.95) but not by exclosure status. The positive influence of exclosures on nest survival was not offset by a reduction in chick or adult survival, indicating that exclosures are a viable tool for piping plover conservation. [ABSTRACT FROM AUTHOR]

Many shorebirds rely on small numbers of staging sites during long annual migrations. Numerous shorebird species are declining and understanding the importance of these staging sites is important for successful conservation. We surveyed endangered rufa red knots (Calidris canutus rufa) staging in James Bay, Ontario, Canada, during southbound migration in 2017 and 2018. We used mark‐resight data and count data in an integrated Bayesian analysis to quantify migration phenology, estimate passage population size, and model the age structure of the stopover population. Many adult red knots arrived in James Bay in a single wave in early August in 2017, whereas adult red knots arrived in multiple smaller waves in July and mid‐August in 2018. These waves may correspond with breeding phenology where more red knots bred successfully and arrived in one large event in 2017 and the higher number of earlier arrivals in July 2018 may have been failed breeders. We included a binomial generalized linear model in the integrated analysis to estimate that 20% and 10% of staging red knots were juveniles in 2017 and 2018, respectively. In future applications, this method could provide a metric to assess breeding performance and develop our understanding of its role in population declines. Overall, we estimated that up to 23% of the estimated rufa red knot population staged in southwestern James Bay for an average of 10–12 days. The region is a key staging site for endangered red knots and could be included in conservation planning. © 2021 The Wildlife Society. : We used an integrated Bayesian analysis to estimate passage population size and migration phenology of endangered red knots staging in southwestern James Bay, Ontario, Canada during southbound migration. Our integrated analysis included a method to model the age structure of the population, which could be used as a tool to monitor breeding success. [ABSTRACT FROM AUTHOR]

Sea level rise (SLR) and disturbances from increased storm activity are expected to diminish coastal ecosystems available to nesting species by removing habitat and inundating nests during incubation. We updated the United States Geological Survey's (USGS) Coastal Vulnerability Index, which provides a qualitative and relative assessment of a coastal area's vulnerability to erosion and shoreline retreat as a function of SLR and other factors, for the South Atlantic Bight. We considered a eustatic SLR projection of 14 cm by 2030. We linked long‐term survey data for 3 sea turtle species, 3 shorebird species, and 5 seabird species to future coastal erosion vulnerability to SLR to understand effects of future SLR on nesting habitats. Over 2,000 km (43%) of the South Atlantic Bight coastline is projected to have an increase in coastal erosion vulnerability by the 2030s, with respect to its present vulnerability. Future vulnerability of SLR‐induced erosion along the South Atlantic Bight is spatially variable, and the 11 coastal study species also varied in their use of coastal habitats with high future coastal vulnerability to SLR. For example, only 23% of high‐density nesting habitat for the brown pelican (Pelecanus occidentalis) is expected to be at increased vulnerability to SLR, whereas >70% of the high‐nesting density habitat for 2 seabird species (gull‐billed tern [Gelochelidon nilotica], sandwich tern [Thalasseus sandvicensis]) is predicted to have higher future coastal erosion vulnerability by 2030. We provide predictions for the level of susceptibility of the study species to erosion from future SLR, which is the first step in managing coastal species for the changing environmental conditions associated with climate change and SLR. © 2019 The Authors. Journal of Wildlife Management Published by Wiley Periodicals, Inc. on behalf of The Wildlife Society. Erosion from future sea level rise varies along the South Atlantic Bight, and the degree of use of vulnerable habitats varies among 11 coastal study species. Conservation managers can use our broad‐scale approach to align high nesting density habitats with those areas predicted to have high future coastal vulnerability. [ABSTRACT FROM AUTHOR]

Shorebird populations worldwide are declining because of habitat loss from sea‐level rise, accelerated erosion, development, and recreational land use. To better understand the consequences of human recreational activity, we monitored survival, habitat use, condition, and behavior of pre‐fledged piping plover (Charadrius melodus) chicks on Fire Island and Westhampton Island, New York, 2013–2015. Broods experienced varying levels of recreational land use (low‐use, moderate‐use, high‐use, and high off‐road vehicle‐use), and recreational use was higher on weekends (Friday–Sunday) than weekdays. Chick daily survival rates were lowest on weekends and increased with time since weekend. Chicks that hatched in areas with low recreational use were more likely to survive to fledging (25 days; x¯ = 0.82 ± 0.08 SE) than those that hatched in areas of high recreational use (x¯ = 0.19 ± 0.05). In addition, chicks hatched in areas of high recreational use fledged at a later age than those hatched in areas of low or moderate recreational use. On weekends, chicks spent less time in foraging habitat (with higher prey abundance), less time foraging, and made fewer foraging attempts per minute than they did on weekdays. These results suggest that recreational activity on beaches pushed foraging plover chicks into habitats with lower food availability, resulting in lower feeding rates, slower growth, and decreased survival. Recreational use of coastal areas can limit the functional availability of shorebird foraging habitat, particularly intertidal foraging habitat, resulting in demographic consequences. © 2018 The Wildlife Society. To better understand the consequences of human recreational activity, we monitored survival, habitat use, condition, and behavior of pre‐fledged piping plover (Charadrius melodus) chicks. Chicks that hatched in areas with low recreational use were more likely to survive to fledging than those in areas of high recreational use, and on weekends (when recreational use was highest) chicks spent a lower proportion of their time in higher‐quality foraging habitat, spent a lower proportion of their time foraging, made fewer foraging attempts per minute, and had lower survival than on weekdays. These results are consistent with the hypothesis that recreational use can reduce piping plover reproductive output. [ABSTRACT FROM AUTHOR]

ABSTRACT: Despite intensive management to protect the federally threatened piping plover (Charadrius melodus), breeding success in North Carolina has consistently been lower than in other Atlantic Coast states. The native ghost crab (Ocypode quadrata) preys on plover eggs and chicks, but the effect of ghost crab predation on plover productivity has not been established. We used daily records of nest survival collected at Cape Hatteras National Seashore, North Carolina, USA from 2008 to 2015 to test a hypothesized negative relationship between the presence of ghost crabs within the 3‐m diameter nest exclosure and the daily nest survival of plovers. We detected ghost crabs or their burrows within the nest exclosure on 63 out of 2,347 nest visits (24 out of 94 nests, 25%). We determined 9 nests (9.6%) were depredated by ghost crabs and 2 nests were abandoned after ghost crab visits. The estimated daily survival rate (DSR) of plover nests decreased with nest age, so to compare the nesting success predicted by our model, we standardized age in the prediction as the age at mid‐incubation. At mid‐incubation (nest age = 19 days), the DSR of a nest found with evidence of ghost crabs was 0.92 (95% CI = 0.74–0.98), compared to DSR of nests without ghost crabs (0.99, 95% CI = 0.97–0.99). We tested other covariates (e.g., clutch size, breeding timing, daily weather conditions); however, the standardized effect size of the presence of ghost crab was more than twice that of all other covariates. Ghost crabs may have a previously under‐recognized effect on plover nest survival when avian and mammalian predation is precluded by nest exclosures. Protection of piping plover nests from ghost crabs may improve piping plover nest success. © 2018 The Wildlife Society. [ABSTRACT FROM AUTHOR]

ABSTRACT Effective conservation of migratory shorebirds requires information on their stopover ecology and migratory connectivity in areas such as the Great Basin and interior California, USA, where freshwater is highly managed and maintenance of wetland networks requires planning across multiple regions. We captured long-billed dowitchers ( Limnodromus scolopaceus; hereafter dowitchers) to study their molt patterns and length of stay in the Klamath Basin during fall migration and their migratory connectivity and over-winter space use in California's Central Valley. Most dowitchers were in active primary molt when captured (83%, n = 116), and molt stage increased during August and September. Radio-tagged dowitchers had an average length of stay after capture of 31.9 days ( n = 54). After departing the Klamath Basin, we located 57% of 81 radio-tagged dowitchers in the Central Valley from December to February; most of the 228 detections occurred in the Sacramento Valley (39%) or Grasslands Ecological Area in the San Joaquin Basin (47%). Space use by radio-tagged dowitchers differed among the Sacramento Valley, San Joaquin Basin, and Sacramento-San Joaquin Delta sub-regions, which demonstrated the influence of varying amounts and distributions of habitat. We recommend that managers in the Klamath Basin provide shallow-water wetlands to support migrant dowitchers for ≥30 days beginning around 1 August, but ideally wetlands should be maintained until 30 September if freshwater supplies are available. We also recommend coordinated management of shallow-water wetlands within and between the Klamath Basin and Central Valley to optimize the use of freshwater, a limited and unreliable resource. © 2015 The Wildlife Society. [ABSTRACT FROM AUTHOR]

River flow management and modification is a global issue, and its effects on river-dependent organisms are pervasive. Flow modification can directly affect avian species through mortality or habitat loss, but less is known about indirect and sublethal effects of flow modification on reproductive output in these species. Young birds are more vulnerable to predation between hatching and fledging than after flight is achieved, but tradeoffs must be made to balance growth and survival. Predation pressure appears to be a significant factor affecting the time to fledging in altricial birds, but less is known about this threat for precocial birds. Birds reaching fledging earlier should have greater rates of survival to migration because their predator escape repertoire includes flight at an earlier age. We evaluated the effect of varying outflows from the Gavins Point Dam on the growth, age at fledging, and survival of piping plover ( Charadrius melodus) chicks on the Missouri River (2006-2009). The study was characterized by 2 relatively high flow years (2006 and 2009) and 2 relatively low flow years (2007 and 2008). We used success rate in recapturing chicks in capture-mark-recapture models as an index for fledging. We attempted to recapture all chicks ( n = 1,099) by hand every 3-4 days throughout the season to acquire morphological measurements. Models indicated that as flows from the dam increased, age at fledging increased. We also found that increasing flows were associated with decreasing daily survival rates ( βflow = −2.401, 95% CI: −4.351 to −0.452). Flow was also negatively related to chick mass gain, but we found less evidence for an effect on wing-chord length. Increased flows covered wet-substrate foraging habitat, and likely affected plover reproductive output directly through chick survival and indirectly through decreased growth and increased fledging times. © The Wildlife Society, 2013 [ABSTRACT FROM AUTHOR]

Loss of breeding habitat and nest predation have contributed to the decline of many shorebird species. The United States Army Corps of Engineers (USACE) initiated a piping plover (Charadrius melodus) habitat creation and augmentation program on the Missouri River in the summer of 2004. The USACE increased unvegetated sandbar habitat by depositing dredged material (engineered sandbars) and by clearing vegetation from existing sandbars (managed sandbars). We evaluated the effects of this increase in nesting and foraging habitat on habitat selection and nest daily survival rate (DSR) of piping plovers on Lewis and Clark Lake and the Gavins Point Reach of the Missouri River from 2005 to 2007 (n = 623 nests). Piping plovers selected engineered sandbars more often than expected based on area and selected natural and managed habitats less than expected based on area. Daily survival rate on engineered sandbars was significantly higher than on natural or managed sandbars (log odds: 2.50, 95% CI: 1.05-5.94). Thus, plovers' habitat selection may have increased their nesting success. Our results suggest that habitat augmentation may stave off declines in piping plover populations limited by insufficient habitat and low nesting success. [ABSTRACT FROM AUTHOR]

Geographically isolated breeding populations of migratory shorebirds may be demographically connected through shared nonbreeding habitats. We used long-term (1998-2008) mark-recapture data on piping plovers (Charadrius melodus) collected from 7 separate studies located throughout North America to conduct a range-wide analysis of after hatch year apparent survival (ΦAHY). Our objectives were to compare concurrent survival estimates from disparate breeding sites and determine whether estimates followed similar trends or were correlated among breeding populations with shared wintering grounds. Average survival estimates were higher for Great Plains populations (range = 0.69-0.81) than for Great Lakes and Atlantic Coast populations (range = 0.56-0.71). Linear trend models indicated that apparent survival declined in 4 out of 7 populations, was unchanged in 3, and was generally highest among Great Plains populations. Based on a post hoc analysis, we found evidence of correlated year-to-year fluctuations in annual survival among populations wintering primarily along the southeastern United States Atlantic Coast and Gulf Coast. Our results indicate shared overwintering or stopover sites may influence annual variation in survival among geographically disparate breeding populations. Declines in piping plover survival are a cause for concern, and our results highlight the need for conservation efforts to include habitat used during the migratory and wintering periods. [ABSTRACT FROM AUTHOR]

Off-road vehicle (ORV) traffic is one of several forms of disturbance thought to affect shorebirds at migration stopover sites. Attempts to measure disturbance effects on shorebird habitat use and behavior at stopover sites are difficult because ORV disturbance is frequently confounded with habitat and environmental factors. We used a before-after-control-impact experimental design to isolate effects of vehicle disturbance from shorebird responses to environmental and habitat factors. We manipulated disturbance levels within beach closures along South Core Banks, North Carolina, USA, and measured changes in shorebird abundance and location, as well as the activity of one focal species, the sanderling (Calidris alba), within paired control and impact plots. We applied a discrete treatment level of one flee-response-inducing event every 10 minutes on impact plots. We found that disturbance reduced total shorebird and black-bellied plover (Pluvialis squatarola) abundance and reduced relative use of microhabitat zones above the swash zone (wet sand and dry sand) by sanderlings, black-bellied plovers, willets (Tringa semipalmata), and total shorebirds. Sanderlings and total shorebirds increased use of the swash zone in response to vehicle disturbance. Disturbance reduced use of study plots by sanderlings for resting and increased sanderling activity, but we did not detect an effect of vehicle disturbance on sanderling foraging activity. We provide the first estimates of how a discrete level of disturbance affects shorebird distributions among ocean beach microhabitats. Our findings provide a standard to which managers can compare frequency and intensity of disturbance events at other shorebird stopover and roosting sites and indicate that limiting disturbance will contribute to use of a site by migratory shorebirds. [ABSTRACT FROM AUTHOR]

We evaluated food habits of 4 species of spring-migrant calidrid sandpipers in the Prairie Pothole Region (PPR) of North Dakota. Sandpipers foraged in several wetland classes and fed primarily on aquatic dipterans, mostly larvae, and the midge family Chironomidae was the primary food eaten. Larger sandpiper species foraged in deeper water and took larger larvae than did smaller sandpipers. The diverse wetland habitats that migrant shorebirds use in the PPR suggest a landscape-level approach be applied to wetland conservation efforts. We recommend that managers use livestock grazing and other tools, where applicable, to keep shallow, freshwater wetlands from becoming choked with emergent vegetation limiting chironomid production and preventing shorebird use. [ABSTRACT FROM AUTHOR]

Two challenges in wildlife telemetry are optimizing the duration of transmitter attachment and minimizing the impacts of radios on the behavior and demography of the study animal. We tested 4 methods of radio attachment for a breeding population of upland sandpipers (Bartramia longicauda) under natural conditions at a tallgrass prairie site in Kansas, USA. To estimate radio retention and weekly survival rates, we used the nest survival model of Program MARK. Radio retention was lowest at the start and the end of the breeding period. The expected duration of radio retention was 1.8 years for a leg-loop harness, 40 days for radios glued to clipped feathers, 26 days for radios glued directly to feathers, and 7 days for radios glued to bare skin. Few radiomarked birds died during our study, but 4 of 8 mortality events were discovered within one week of radiomarking. Both glue and harnesses increased predation risk immediately after radio attachment. The weekly probability of survival was high after a 1-week acclimation period, and the expected survival for a 10- week breeding period was similar in males and females. Attachment of radios with glue had no effect on annual return rates. However, attachment of radios with leg harnesses resulted in lower return rates among radiomarked birds than birds without radios. Radios attached with glue were shed in <1 year but radios attached with harnesses were retained for up to 1-2 years. Our results indicate a tradeoff between optimizing radio retention and minimizing impacts on demography. Glue techniques had retention rates that were suitable for only short-term studies, but attachment with glue had no long-term effect on annual return rates. Leg harnesses provided effective radio retention that had little effect on survival rates during the stationary breeding period, but resulted in lower annual return rates. Robust estimates of radio retention and survival will assist researchers in selecting attachment techniques that best meet the study goals of future telemetry projects. [ABSTRACT FROM AUTHOR]

Complete population estimates for widely distributed species are rarely possible. However, for the third time in 10 years, an International Piping Plover (Charadrius melodus) Breeding and Winter Census was conducted throughout the species range in 2001. Nearly 1,400 participants from 32 U.S. states and Puerto Rico; 9 Canadian provinces; St. Pierre and Miquelon, France; Cuba; and the Bahamas visited 2,244 sites covering 11,836 km of shoreline habitat. During the winter census, 2,389 piping plovers were observed at 33.5% of potentially occupied sites (n = 352). Of these, 56.8% had ≤10 birds present. The breeding census recorded 5,945 adults at 777 of 1,892 sites surveyed. More than 80% of sites with piping plovers present had ≤10 birds. Results indicated an 8.4% increase from 1991 but only a 0.2% increase since 1996. Regional trends suggest that since 1991, number of breeding birds increased on the Atlantic Coast by 78% (2,920 birds; 12.4% increase since 1996) and by 80% in the Great Lakes (72 birds; 50% increase since 1996). However, plovers declined 15% (2,953 birds; 10% decline since 1996) in Prairie Canada/U.S. northern Great Plains. Subregional trends since 1991 reflect a 32.4% decline in Prairie Canada (972 birds; 42.4% decline since 1996), a 2.5% decline in the U.S. northern Great Plains (1,981 birds; 24% increase since 1996), 5.5% decline in eastern Canada (481 birds; 14% increase since 1996), although a 66.2% increase on the U.S. Atlantic Coast (2,430 birds; 12% since 1996). While numbers were down in much of the U.S. northern Great Plains since 1996, an increase (460%, 1,048 birds; 67.7% increase since 1991) was detected on the Missouri River. Results from 3 complete species census efforts provide essential data for conservation planning and assessment and illustrate the utility of global censuses for species of concern. [ABSTRACT FROM AUTHOR]