Shorebird Conservation & Management

Contributed Oral Presentations

SESSION NUMBER: 73

Contributed paper sessions will be available on-demand for the duration of the conference, then again at the conclusion of the conference.

 

Population Genetics of Roseate Terns in North America
Paige A. Byerly
Anthropogenic disturbances such as population declines and habitat fragmentation are known alter dispersal patterns among subpopulations of wildlife, potentially leading to reproductive isolation that can contribute to reduced genetic diversity. While these effects are well-documented in terrestrial wildlife, barriers to dispersal of highly vagile taxa such as seabirds are less understood. Roseate Terns (Sterna dougallii) are a globally distributed seabird species, but populations tend to be patchy, and the species is declining across most of its range. In North America, the Roseate Tern subspecies S. d. dougallii is delineated into a federally endangered Northwestern Atlantic population and a threatened Caribbeanpopulation, both of which experienced major declines in the early 20th century. There is thought to be no gene flow between these two populations, an assumption based on geographic separation, morphological differences, and a lack of band returns; however, there may be potential for interbreeding, and the question of movement among these populations warrants further investigation. We investigated connectivity of Roseate Tern populations in North America to evaluate if historical population declines and habitat fragmentation have contributed to contemporary declines by inhibiting dispersal. We used SNP genomic markers generated via high-throughput sequencing to evaluate relatedness, population structuring, and population genomic parameters such as inbreeding among breeding populations of Roseate Terns in the Northeastern United States, Florida, and the Virgin Islands. We found evidence for differentiation among the Northeastern and Caribbean populations. Our results suggest that historical dispersal patterns may have been altered by anthropogenic activities and population declines, and that low genetic diversity may inhibit recovery of both populations.
Remote Sensing and Wildlife Management: Using Object Based Image Analysis for the Detection of Nesting Laughing Gulls
Benjamin F. Martini; Douglas A. Miller
Remote sensing has long been used to study wildlife, however manual methods of detecting wildlife in aerial imagery are often time consuming and prone to human error. Object based image analysis (OBIA) is a promising new technology that addresses both these issues through automation; however, it has not yet been extensively applied to wildlife surveys. We are using the OBIA software eCognition to detect the nests of a breeding colony of Laughing gulls (Leucophaeus atricilla) in Joco Marsh as part of an ongoing monitoring effort at the John F Kennedy International Airport conducted by the USDA. Our technique uses a combination of high resolution 4-band aerial imagery, LiDAR point cloud data, and land cover data as part of a feature extraction ruleset that classifies nest objects using the site, tone, shape, size, and association elements of image interpretation. Preliminary testing on a subset of the imagery revealed that our ruleset was successful at extracting 89% of the nests; however, it also had a high rate of errors of commission due to similarities between the nests and surrounding dead vegetation. After scaling up to the full set of imagery and fine tuning the ruleset using sublevel objects, we achieved a nest extraction rate of 97% while simultaneous reducing errors of commission from 50% to 34%. Although ruleset refinement remains ongoing, our results thus far demonstrate the value of this technology for detecting the nests of colonial nesting shorebirds like the laughing gull, as well as the value of OBIA techniques to wildlife sciences. This approach removes the need to manually search entire sets of imagery for nests and changes the user’s task to verifying output results and eliminating known errors of commission that the software is unable to differentiate from actual nests, a much more efficient and less error prone methodology.
Impacts of Extreme Disturbances at Wintering Areas on Piping Plover Survival and Migratory Connectivity
Kristen Ellis; Michael Anteau; Francesca Cuthbert; Cheri Gratto-Trevor; Joel Jorgensen; David Koons; David Newstead; Larkin Powell; Megan Ring; Mark Sherfy; Rose Swift; Dustin Toy
Effective conservation for listed migratory species requires understanding linkages between breeding and non-breeding areas. Environmental conditions away from breeding areas may have important impacts on demography of these species because most of the annual cycle occurs outside breeding areas. Piping Plovers (Charadrius melodus) are a federally-listed migratory species that periodically experience extreme environmental disturbances on wintering areas, including oil spills, toxic algal blooms, and hurricanes. Further, strong site fidelity of Piping Plovers at wintering areas emphasizes potential exposure to these disturbances. To evaluate how these disturbances impact survival and migratory connectivity, we implemented a seasonal multistate model (6 geographic areas representing 3 breeding and 3 wintering areas). We used capture and resighting data collected between 2002 – 2019 from Northern Great Plains USA, Southern Great Plains USA, and Prairie Canada breeding areas. Individuals from all breeding areas were more likely to migrate to the western Gulf of Mexico (Texas and Mexico) than to the eastern Gulf of Mexico or the Bahamas and Atlantic coast, although individuals from breeding areas mixed across all winter areas. Hurricanes and oil spills appeared to negatively influence wintering-season survival. Despite concerns over increased frequency of these extreme disturbances, we did not detect a negative trend in adult survival throughout our study period. Mixing among individuals at wintering areas may provide a buffering effect against impacts of extreme events on any one breeding sub-population. Our results moreover suggest that understanding migratory connectivity and linking seasonal threats to population dynamics can better inform conservation strategies for Piping Plovers.
Experimental Evaluation of Predator Exclosures on Nest, Chick, and Adult Survival of Piping Plovers
Michael J. Anteau; Rose J. Swift; Mark H. Sherfy; David N. Koons; Terry L. Shaffer; Dustin L. Toy; Megan M. Ring
Species of conservation concern often receive intensive management to improve vital rates and facilitate recovery. Piping Plovers (Charadrius melodus) are federally listed and concerns over nest depredation have prompted widespread use of plover-permeable predator exclosures placed around nests. While effectiveness of exclosures for improving nest survival has been demonstrated, concerns remain about 1) deceases in chick survival (density-dependent processes) or 2) increased vulnerability of adults to predation. Either concern could demographically outweigh benefits of increased nest survival. We used a designed experiment to evaluate survival of uniquely identified nests (n=506), chicks (n=461), and adults (n=669) at wetlands across the Northern Great Plains during 2014-2016. We randomly assigned wetlands (n2014=33, n2015=29, n2016=41) into three treatments that received exclosures on all, half, or none (control) of the nests. Exclosed nests had greater cumulative survival (0.73 [0.70-0.77 85%CI]) than unexclosed nests on half-treated wetlands (0.58 [0.54-0.62]) or unexclosed nests on control wetlands (0.52 [0.49-0.56]). Cumulative chick survival rates were relatively high (0.83-0.89) and were similar across treatments. Cumulative survival of adults during incubation varied by treatment, but adults on exclosed nests (0.90 [0.88-0.93]) and unexclosed nests on half-treated wetlands (0.89 [0.86-0.92]) had greater survival than those on unexclosed nests on control wetlands (0.75 [0.64-0.84]). Adult annual survival rates varied by year (0.79-0.95), but not treatment. We found that the positive influence of exclosures on nest survival was not offset by reduced chick or adult survival, indicating that exclosures are a viable tool for plover conservation.
Simulating Piping Plover Nesting Success As a Function of Predator and Plover Sensitivity to Human Disturbance
Samantha Smock; Alexander Cohen; Dr. Patrick Zollner
Piping plovers (Charadrius melodus) are federally threatened shorebirds that are heavily impacted by human disturbance on beaches. Predation is another significant disturbance that negatively affects plover chick survival. Both plovers and their predators are impacted by human presence, but it is less clear how the response of predators to humans will influence the survival of their prey. Humans may create predator-free space for plovers or they may attract predators increasing encounters with plovers. Individual-Based modeling (IBM) is a valuable tool for predicting population responses to complex circumstances like the consequences of the direct and indirect interactions of predator and prey species with disturbance caused by human recreation. We developed an IBM and used it to simulate the responses of plovers and two archetypically different plover predators to human recreation in beach environments. We investigated the effects of human density, beach configuration, and predator species that are either synanthropic or wary of humans upon plover chick survival, nest survival, and the flushing frequency of plover from predators and humans. We found that interactions between predators and humans do adversely impact plover chick survival. Higher human density was a major indicator of declining plover chick survival. Narrower beaches reduced nest survival, but beach width was not a strong predictor. Predator type was a major indicator of plover flushing rates in response to both predators and humans. We conclude that synanthropic predators may be more efficient at killing plover chicks because human activity drives them away from the beach environment less frequently than other predators. Overall, our results suggest that the interactive effect of predators and humans can impact plover nesting success. Beach managers should acknowledge the attractive or repellent effects that humans have on predators in creation of their management plans for plovers.

 

Virtual
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