Contaminants in Eggs of Western Snowy Plovers and California Least Terns: Is There a Link to Population Decline?

2000 ◽  
Vol 65 (1) ◽  
pp. 42-50 ◽  
Author(s):  
R. L. Hothem ◽  
A. N. Powell
Keyword(s):  
Population Decline ◽  
Least Terns ◽  
Snowy Plovers ◽  
Western Snowy Plovers

Habitat Use and Reproductive Success of Western Snowy Plovers at New Nesting Areas Created for California Least Terns

2000 ◽  
Vol 64 (1) ◽  
pp. 24 ◽  
Author(s):  
Abby N. Powell ◽  
Christine L. Collier
Keyword(s):  
Reproductive Success ◽  
Habitat Use ◽  
Least Terns ◽  
Snowy Plovers ◽  
Western Snowy Plovers

Human dimensions of predator management for threatened Western Snowy Plovers

Wader Study ◽  
2021 ◽  
Vol 128 (1) ◽  
Author(s):  
Barbara Clucas
Keyword(s):  
Human Dimensions ◽  
Predator Management ◽  
Snowy Plovers ◽  
Western Snowy Plovers

Incubating snowy plovers (Charadrius nivosus) exhibit site-specific patterns of disturbance from human activities

2016 ◽  
Vol 43 (4) ◽  
pp. 288 ◽  
Author(s):  
Cara A. Faillace ◽  
Bradley W. Smith
Keyword(s):  
Human Activities ◽  
Population Decline ◽  
Breeding Population ◽  
Perceived Threat ◽  
Model Framework ◽  
Site Specific ◽  
Beach Width ◽  
Single Person ◽  
Snowy Plovers ◽  
Range Of Variation

Context Many shorebirds are threatened by human-caused disturbance. For snowy plovers, disturbance within nesting habitats has been implicated as a major contributing factor in their population decline through deleterious effects on breeding success. Very little is known about site specificity of disturbance from human activities for this species. Aims We examined the disturbance of incubating snowy plovers to determine if nesting shorebirds within one breeding population exhibited site-specific patterns of disturbance from human activities. Methods We recorded flush (i.e. flight or escape from a perceived threat) distances and time spent off the nest following approach by a single person on Sanibel and Cayo Costa Islands, two islands in south-west Florida that differ in daily human visitation, and by a person walking a dog on Sanibel. We used a Bayesian model framework to determine effects of location and approach type on flush distance and time spent off of the nest. Key results Birds nesting on Sanibel flushed at shorter distances from a solitary person without a dog than did birds nesting on Cayo Costa, but spent similar amounts of time off of nests following a flush. On Sanibel, nesting birds also flushed at significantly greater distances and spent significantly more time off of nests when flushed by a person walking a dog rather than by a person alone. Conclusions Within a population, nesting snowy plovers exhibit site- and stimulus-dependent patterns of disturbance. The intraspecific variation falls within the range of variation recorded among species of birds studied elsewhere. Although we cannot determine causation, we suggest habituation to human activities from a combination of high beach usage, smaller nesting exclusion zones, and narrower beach width on Sanibel compared to Cayo Costa as a likely explanation for this difference. Implications Set-back distances for symbolic fencing have been generalised across species and nesting locations. Our results suggest that disturbance of nesting shorebirds can be site-dependent even within one breeding population of a species. Set-back distances around shorebird nests must account for location and types of activities encountered, implying the need for more conservative implementation of set-back distances.

scholarly journals Factors influencing the abundance of wintering western snowy plovers at Crown Memorial State Beach

2021 ◽  
Vol 107 (3) ◽  
pp. 249-259
Author(s):  
David L. Riensche
Keyword(s):  
Prey Availability ◽  
Habitat Choice ◽  
Protection Zone ◽  
The Public ◽  
Nonbreeding Season ◽  
Significant Difference ◽  
Food Shortages ◽  
Snowy Plovers ◽  
Shorebird Habitat ◽  
Western Snowy Plovers

Survival during the nonbreeding season, when mortality from food shortages and raptor predation is highest, influences shorebird population growth. These selection pressures, as well as anthropogenic influences, can shape wintering shorebird habitat use patterns. The western snowy plover (Charadrius alexandrinus nivosus) is a small shorebird that uses sand-spits, dune-backed beaches, open areas around estuaries for foraging and roosting. The Pacific Coast population of western snowy plovers is listed as a federally threatened species and a California Species of Special Concern. Previous studies suggest humans, dogs and corvids are sources of disturbance to plovers on public beaches. During 2014 to 2019, these disturbance factors were examined at Robert W. Crown Memorial State Beach in Alameda, California. In decreasing order of impact, the beach using public, corvids, and dogs were found to be the major stressors to over wintering plovers. Both the public and corvids respectively, resulted in disturbance and avoidance behaviors by plovers nearly 40% of the time. In 2015, the District created the Plover Protection Zone (PPZ) by installing symbolic fencing, signage, and establishing a volunteer team to monitor plovers and educate the public. In 2016, the potential prey abundance within the plover protection zone and areas directly north and south were examined using core samples and sticky traps. Statistical analysis showed a significant difference in the amount of macro-invertebrate prey available in the area used by the plovers as compared to other locations. Habitat choice and prey availability are vital to wintering shorebird. During this study, the wintering population of western snowy plovers increased from six to over 54 individuals.

scholarly journals Using Decision Science for Monitoring Threatened Western Snowy Plovers to Inform Recovery

Animals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 569
Author(s):  
Bruce G. Marcot ◽  
James E. Lyons ◽  
Daniel C. Elbert ◽  
Laura Todd
Keyword(s):  
Performance Measures ◽  
Risk Attitude ◽  
Cost Effective ◽  
Monitoring Methods ◽  
Optimal Decisions ◽  
The Us ◽  
Fish And Wildlife Service ◽  
Snowy Plovers ◽  
On The Road ◽  
Western Snowy Plovers

Western Snowy Plovers (Charadrius nivosus nivosus) are federally listed under the US Endangered Species Act as Threatened. They occur along the US Pacific coastline and are threatened by habitat loss and destruction and excessive levels of predation and human disturbance. Populations have been monitored since the 1970s for distribution, reproduction, and survival. Since the species was federally listed in 1993 and a recovery plan was approved under the US Fish and Wildlife Service in 2007, recovery actions have resulted in growing populations with increased presence at breeding and wintering sites throughout their Pacific Coast range. This success has created logistical challenges related to monitoring a recovering species and a need for identifying and instituting the best monitoring approach given recovery goals, budgets, and the likelihood of monitoring success. We devised and implemented a structured decision analysis to evaluate nine alternative monitoring strategies. The analysis included inviting plover biologists involved in monitoring to score each strategy according to a suite of performance measures. Using multi-attribute utility theory, we combined scores across the performance measures for each monitoring strategy, and applied weighted utility values to show the implications of tradeoffs and find optimal decisions. We evaluated four scenarios for weighting the monitoring objectives and how risk attitude affects optimal decisions. This resulted in identifying six strategies that best meet recovery needs and were Pareto optimal for cost-effective monitoring. Results were presented to the US Fish and Wildlife Service, responsible for monitoring as well as for consideration to ensure consistent monitoring methods across the species’ range. Our use of structured decision-making can be applied to cases of other species once imperiled but now on the road to recovery.

Monitoring Western Snowy Plover Nests with Remote Surveillance Systems in San Francisco Bay, California

2012 ◽  
Vol 3 (1) ◽  
pp. 123-132 ◽  
Author(s):  
Scott A. Demers ◽  
Catilin W. Robinson-Nilsen
Keyword(s):  
San Francisco ◽  
Human Disturbance ◽  
Surveillance System ◽  
Management Practices ◽  
San Francisco Bay ◽  
Behavioral Studies ◽  
Snowy Plover ◽  
Snowy Plovers ◽  
Nest Predators ◽  
Western Snowy Plovers

Abstract The western snowy plover Charadrius nivosus nivosus is listed as threatened under the U.S. Endangered Species Act of 1973 due to long-term population declines related, in part, to nest predation and human disturbance. In San Francisco Bay, California, numbers of predators of western snowy plovers and the potential for recreation-based human disturbances have increased during the past few decades and will likely increase for the foreseeable future. In an attempt to increase the reproductive success of western snowy plovers, managers have dedicated considerable resources to management practices including predator removal and habitat enhancement projects in San Francisco Bay. The unequivocal identification of western snowy plover nest predators and information regarding the behavioral responses of nesting plovers to human disturbance would inform management practices for this species. Therefore, we examined the efficacy of using a digital video surveillance system to identify nest predators of western snowy plovers in former salt evaporation ponds in San Francisco Bay and to assess its potential for use in behavioral studies. This system was designed to minimize disturbance to nesting plovers and limit predator bias at breeding sites that had little or no cover to camouflage or protect the equipment. The system included a small camera with infrared lights placed approximately 20 m from nests and a continuously operating recording unit and power supply that was positioned up to 300 m from nests. The system could be deployed within 20 min, run continuously for up to 5 d, and data could be retrieved without disturbing nesting birds. During a 2-y study period, we recorded six species depredating plover eggs and chicks: red-tailed hawk Buteo jamaicensis, common raven Corvus corax, California gull Larus californicus, northern harrier Circus cyaneus, ruddy turnstone Arenaria interpres, and gray fox Urocyon cinereoargenteus. Our results suggest that this surveillance system was effective for identifying western snowy plover nest predators, and the presence of the camera did not influence nesting success of monitored nests. This system could be integrated into conservation programs intended to improve reproductive success of this species and could be useful for conducting behavioral studies of western snowy plovers and other species.

Habitat selection by western snowy plovers during the nonbreeding season

2011 ◽  
Vol 75 (4) ◽  
pp. 786-793 ◽  
Author(s):  
Kevin M. Brindock ◽  
Mark A. Colwell
Keyword(s):  
Habitat Selection ◽  
Nonbreeding Season ◽  
Snowy Plovers ◽  
Western Snowy Plovers

Western Snowy Plovers Charadrius alexandrinus nivosus select nesting substrates that enhance egg crypsis and improve nest survival

Ibis ◽  
2011 ◽  
Vol 153 (2) ◽  
pp. 303-311 ◽  
Author(s):  
MARK A. COLWELL ◽  
JASON J. MEYER ◽  
MICHAEL A. HARDY ◽  
SEAN E. MCALLISTER ◽  
AMBER N. TRANSOU ◽  
...  
Keyword(s):  
Nest Survival ◽  
Charadrius Alexandrinus ◽  
Snowy Plovers ◽  
Egg Crypsis ◽  
Western Snowy Plovers

scholarly journals Habitat Characteristics and Nest Success of Snowy Plovers Associated with California Least Tern Colonies

The Condor ◽  
2001 ◽  
Vol 103 (4) ◽  
pp. 785-792
Author(s):  
Abby N. Powell
Keyword(s):  
Social Factors ◽  
San Diego ◽  
Nest Success ◽  
Habitat Characteristics ◽  
Egg Predation ◽  
Sterna Antillarum ◽  
Charadrius Alexandrinus ◽  
Least Terns ◽  
Least Tern ◽  
Snowy Plovers

AbstractNest success of Snowy Plovers (Charadrius alexandrinus) was estimated at six sites in San Diego County, California, to determine the effects of habitat characteristics and social factors on predation risk. Egg predation was expected to be lower for plovers nesting among Least Terns (Sterna antillarum) because of benefits associated with nesting under the “protective umbrella” of a colonial species. Snowy Plovers nested adjacent to objects and in areas with more vegetation cover than random sites in beach and fill habitats and in areas with more debris cover in beach and salt pan habitats. Estimated nest success from 1994–1997 was 50%, and most predation was attributed to corvids, primarily Common Ravens (Corvus corax). Social factors, including distance to nearest Least Tern and Snowy Plover nests, predicted nest success whereas habitat characteristics did not. Nest success was greatest for plovers nesting closest to an active tern nest and nesting at intermediate distances to conspecifics. Nest success also varied among years and sites, with two sites consistently less successful over the four years. Nests within tern colonies received some mitigation of egg predation. Plover nests initiated prior to the arrival of Least Terns were less likely to hatch eggs than later nests; nevertheless, Snowy Plovers in southern California initiated nesting well before Least Terns.Características del Hábitat y Éxito de la Nidada de Charadrius alexandrinus Asociados a Colonias de Sterna antillarumResumen. Para determinar los efectos de las características del hábitat y factores sociales sobre el riesgo de depredación, estimé el éxito de las nidadas de Charadrius alexandrinus en seis sitios del Condado de San Diego, California. Se esperaba que la depredación de huevos fuera menor para los C. alexandrinus que anidan junto a Sterna antillarum debido a los beneficios de anidar bajo un “paraguas protector” de una especie colonial. En playas y hábitats rellenados, C. alexandrinus anidó con mayor frecuencia en lugares adyacentes a objetos y en áreas con mayor cobertura de vegetación que en sitios aleatorios y en áreas con mayor cobertura de desechos vegetales en playas y salinas. El éxito estimado de las nidadas entre 1994–1997 fue de 50%, y la mayor tasa de depredación fue atribuida a córvidos, principalmente a la especie Corvus corax. Factores sociales como distancia al nido más cercano de S. antillarum y C. alexandrinus predijeron el éxito de la nidada, mientras que las características del hábitat no lo hicieron. El éxito de la nidada fue mayor para los individuos de C. alexandrinus que nidificaron más cerca de un nido activo de S. antillarum y que nidificaron a distancias intermedias de conespecíficos. El éxito de la nidada también varió entre años y sitios. Dos sitios presentaron consistentemente un menor éxito durante los cuatro años de estudio. Los nidos ubicados dentro de la colonia presentaron una leve disminución en la depredación de huevos. Los huevos de nidos de C. alexandrinus iniciados antes de la llegada de S. antillarum tuvieron una menor probabilidad de eclosión que huevos de nidos más tardíos. Sin embargo, C. alexandrinus comenzó a nidificar bastante antes que S. antillarum en California del Sur.

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