The American Oystercatcher (Haematopus palliatus) Working Group formed spontaneously in 2001 as coastal waterbird biologists recognized the potential for American Oystercatchers to serve as focal species for collaborative research and management. Accomplishments over the past 15 years include the establishment of rangewide surveys, color-banding protocols, mark-resight studies, a revision of the Birds of North America species account, and new mechanisms for sharing ideas and data. Collaborations among State, Federal, and private sector scientists, natural resource managers, and dedicated volunteers have provided insights into the biology and conservation of American Oystercatchers in the United States and abroad that would not have been possible without the relationships formed through the Working Group. These accomplishments illustrate how broad collaborative approaches and the engagement of the public are key elements of effective shorebird conservation programs.

Raccoons (Procyon lotor) are important predators of ground-nesting species in coastal systems. They have been identified as a primary cause of nest failure for the American Oystercatcher (Haematopus palliatus) throughout its range. Concerns over the long-term effects of raccoon predation and increased nest success following a hurricane inspired a mark-resight study of the raccoon population on a barrier island off North Carolina, USA. Approximately half of the raccoons were experimentally removed in 2008. Nests (n = 700) were monitored on two adjacent barrier islands during 2004–2013. Daily nest survival estimates were highest for 2004 (0.974 ± 0.005) and lowest for 2007 and 2008 (0.925 ± 0.009 and 0.925 ± 0.010, respectively). The only model in our candidate set that received any support included island and time of season, along with a diminishing effect of the hurricane and a constant, 5-year effect of the raccoon removal. For both hurricane and raccoon removal, however, the support for island-specific effects was weak (β = -0.204 ± 0.116 and 0.146 ± 0.349, respectively). We conclude that either the raccoon reduction was inadequate, or factors other than predation cause more variation in nest success than previously recognized. A multi-faceted approach to management aimed at reducing nest losses to storm overwash, predation, and human disturbance is likely to yield the largest population level benefits.

The use of digital VHF telemetry is expanding as a lightweight alternative to satellite-based technologies for tracking bird movements, though few studies have compared how they perform. During 2013, satellite telemetry and digital VHF telemetry were compared for estimating the length of stay and home ranges of American Oystercatchers (Haematopus palliatus) on their breeding grounds in Massachusetts, USA. American Oystercatchers (n = 5) were captured at their nest sites and tagged with a 9.5-g solar-powered satellite transmitter and a 1.0-g digitally coded VHF transmitter, and tracked using the Argos satellite system, an array of eight automated radio telemetry stations, and periodic land-based and aerial telemetry surveys. Estimates of mean minimum length of stay in the study area were slightly longer for satellite telemetry at 118 ± 12 days vs. digital VHF telemetry at 108 ± 11 days. Size estimates of mean (± SE) fixed kernel 95% utilization distributions were similar for satellite telemetry (22.53 ± 16.87 km²) and VHF telemetry (27.27 ± 21.58 km²). Despite a small sample size, digital VHF telemetry, when combined with automated radio telemetry stations and telemetry surveys, performed similarly to satellite telemetry for estimating timing and home range size of shorebirds on their breeding grounds.

The conservation of a species is reliant on identifying threats to critical vital rates such as survival and dispersal. Accurate estimates of these vital rates and the factors that affect them can be used to better manage populations. The USA Atlantic Coast population of American Oystercatchers (Haematopus palliatus) benefits from a large-scale conservation effort, but this long-lived species remains especially sensitive to fluctuations in adult survival. The model used here and 8 years of mark-resight data from three breeding populations with varying migration strategies from the United States (migratory: Massachusetts and New Jersey; non-migratory: South Carolina) were used to estimate adult survival and site fidelity. Results indicated a resident population in South Carolina with 100% of the breeding population wintering in that State, a migratory population in Massachusetts with the majority of individuals wintering in Florida (42%), and a partially migratory population in New Jersey with a portion of the breeding population overwintering in that State (33%). Annual adult survival did not vary among populations. Although the average estimate of adult survival was high (0.89), there was an apparent decline in adult survival (from 0.94 to 0.83) over the study period. Given strong site fidelity (0.91), adult mortality is a critical factor for the viability of local populations.

In populations of long-lived species, adult survival typically has a relatively high influence on population growth. From a management perspective, however, adult survival can be difficult to increase in some instances, so other component rates must be considered to reverse population declines. In North Carolina, USA, management to conserve the American Oystercatcher (Haematopus palliatus) targets component vital rates related to fecundity, specifically nest and chick survival. The effectiveness of such a management approach in North Carolina was assessed by creating a three-stage female-based deterministic matrix model. Isoclines were produced from the matrix model to evaluate minimum nest and chick survival rates necessary to reverse population decline, assuming all other vital rates remained stable at mean values. Assuming accurate vital rates, breeding populations within North Carolina appear to be declining. To reverse this decline, combined nest and chick survival would need to increase from 0.14 to ≤ 0.27, a rate that appears to be attainable based on historical estimates. Results are heavily dependent on assumptions of other vital rates, most notably adult survival, revealing the need for accurate estimates of all vital rates to inform management actions. This approach provides valuable insights for evaluating conservation goals for species of concern.

Information on demographic parameters needed to inform conservation strategies for American Oystercatchers (Haematopus palliatus) is lacking. The population dynamics of American Oystercatchers in Virginia, USA, were examined using a multi-state analysis framework that modeled movement of American Oystercatchers into and out of the State. Change in breeding status, age-specific survival rates, and age at first breeding were investigated for three geographically distinct study sites. Non-breeding American Oystercatchers originating from Virginia readily moved in and out of the State among years. The immigration rate for birds breeding on barrier islands was 6% Emigration rates were 6% for the barrier island breeding population and 17% for the seaside lagoon population. Stage-specific annual survival rates were 0.66, 0.95 and 0.91 for juvenile, sub-adult and adult stages, respectively. Age at first breeding peaked in the fourth year for both the barrier island and seaside lagoon breeding populations. Movement and recruitment rates suggested that the barrier islands may provide the highest quality breeding habitat among the three study sites. This study showed that Virginia's American Oystercatcher population is linked with other Atlantic Coast populations, and these links should be considered when evaluating local population trends and management targets.

The western race of the American Oystercatcher (Haematopus palliatus frazari) is a resident and endangered shorebird of western Mexico. Its breeding population and conservation concerns are poorly known, but recent information indicates extremely low numbers and a discrete breeding distribution. Because of loss and degradation of sandy beaches by coastal development and disturbance from human recreational activities, the American Oystercatcher is a priority species in the Shorebird Conservation Plans of the United States and Mexico. Research on its distribution and abundance during the 2009 breeding season resulted in the identification of 2,286 adults in northwest Mexico. Although the population is higher than previous estimates, its distribution is more restricted than expected. It is distributed almost exclusively in northwest Mexico, and 80% of the total breeding population is found on the islands of Sinaloa and Baja California Sur. Based on these results, this species was officially federally listed on the Mexican List of Protected Species in 2010. This legal mechanism will promote the management and protection of this priority subspecies as well as other waterbirds occupying the same habitats.

The Western Atlantic population of the American Oystercatcher (Haematopus palliatus) is of conservation concern, and much effort has been exerted to determine impacts of conservation efforts and identify important sites that need increased protection within the breeding range. Monitoring numbers of nesting pairs and distribution and habitat selection of nesting pairs provides data for conservation programs. The breeding population of American Oystercatchers in North Carolina has been estimated four times since 2004. Locations of territories and nests were recorded and mapped, and sites were categorized according to habitat type (barrier, dredged-material, or natural sand-shell or marsh island) and management responsibility (Federal, State, Audubon North Carolina, private landowner). Estimates indicate the number of nesting pairs changed slightly: 324 in 2004, 346 in 2007, 373 in 2010, and 351 in 2013. Total numbers of individual American Oystercatchers during the breeding season changed from 703 in 2004 to 802 in 2013. Most nesting pairs (159.0 ± 6.0 SE; P ≤ 0.001) are on barrier islands under Federal agency management, followed by nesting pairs on natural islands (117.0 ± 7.2) and dredgedmaterial islands (69.5 ± 6.3).

American Oystercatchers (Haematopus palliatus) are present in North Carolina, USA, year-round. About 6–7% of the total Western Atlantic population winters in North Carolina. To estimate numbers of American Oystercatchers present during the non-breeding season, four major concentration areas were surveyed in North Carolina, each with multiple roost sites, from 2008–2013. Abundance of American Oystercatchers remained generally stable during the study period. The Lower Cape Fear River area had the greatest number of American Oystercatchers in all seasons. Mean peak abundance was greatest during winter at all concentration areas. Peak winter abundance was 158 at Ocracoke Inlet, 265 in Back Sound, 187 in Masonboro Sound, and 470 on the Lower Cape Fear River. Fall abundance was generally greater than spring abundance at all concentration areas except Masonboro Sound. Most banded individuals observed were marked in North Carolina as chicks or nesting adults, and they exhibited fidelity to concentration areas. About 15% of American Oystercatchers used wooden docks as roost sites; the rest used natural substrates and a man-made rock wall. At sites where roost habitat is a limiting factor, fabricated structures might be a useful substitute. Most roost sites receive no protection during the non-breeding season, and we observed sources of potential disturbance on 2.8–50.6% of surveys. Pedestrians and boats were the most common sources of potential disturbance.

The American Oystercatcher (Haematopus palliatus frazari) is federally listed as endangered in Mexico due to habitat loss and small population size. Recent surveys indicate that the State of Sinaloa supports about half of the breeding population in Mexico. However, no information is available about the non-breeding ecology in Mexico. To assess American Oystercatcher distribution, abundance, and roosting habitat use during the nonbreeding season (3 August 2014-23 January 2015), six bays were surveyed in Sinaloa. A total of 1,351 American Oystercatchers were detected using this area based on maximum count per roosting site at or near high tide. American Oystercatchers roosted in flocks of variable size (3–253 individuals per flock) with Bahía Santa María hosting the main roosting sites in Sinaloa. Mangrove islands and mudflats had larger numbers of individuals than expected relative to the availability of those habitats. The non-breeding Sinaloa population comprised approximately 45.0% of the total H. p. frazari population estimate (n = 3,000 individuals). Bahía Santa María represented 74.6% of the non-breeding population observed in Sinaloa. Thus, Sinaloa, and particularly Bahía Santa María, stand out as critical sites for the conservation of this subspecies. Hypothesized threats to American Oystercatchers were predators, livestock, and human activities.

Species distribution modeling has seen widespread use in ecology and conservation over the past two decades, and as a result many questions regarding the predictive capabilities of new techniques have been raised. One modeling approach that has gained popularity is Maxent, which uses presence-only data to model species distributions. Although Maxent is ordinarily used to model a species' fundamental niche at large scales (e.g., continental-scale), this technique was used to develop a predictive model for the realized niche and local breeding distribution of American Oystercatchers (Haematopus palliatus) in coastal New Jersey, USA. The transferability of the predictive model to locations outside training areas was examined in an effort to locate new breeding populations in previously unsurveyed areas. Initial model validation indicated that Maxent performed well, exhibiting good discrimination ability based on analyses of both training data (AUC = 0.95) and test data (AUC = 0.91). Ground surveys based on the final model located 185 previously unknown territorial pairs of American Oystercatchers, showing that Maxent was useful to locate new populations in alternative breeding habitats. However, when validated with an independent dataset, the Maxent model did not perform much better than random (AUC = 0.54), reporting high omission (0.76–0.93) and commission (0.40–0.83) error rates. The poor validation was attributed to source-sink dynamics rather than to errors in the modeling technique. Future researchers attempting to validate species distribution models with ground surveys should take into consideration metapopulation and source-sink theory in the design of surveys and interpretation of results.

Over the course of a 6-year study of American Oystercatchers (Haematopus palliatus), five cases of entanglement in monofilament fishing line were encountered. Two cases resulted in confirmed death, one case resulted in probable death, and two cases resulted in survival but required human intervention. Approximately 2–4% of the study population was represented in these events, which is cause for alarm as monofilament fishing line is a hazard both to American Oystercatchers and other species. This report emphasizes the need for careful responsibility by recreational users of fishing tackle, educational programs to stress this need, and signage to reinforce this message.