scholarly journals Visual Head Counts: A Promising Method for Efficient Monitoring of Diamondback Terrapins

Diversity ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 101 ◽  
Author(s):  
Patricia Levasseur ◽  
Sean Sterrett ◽  
Chris Sutherland
Keyword(s):  
Count Data ◽  
Hierarchical Modeling ◽  
Spatial Scales ◽  
Diamondback Terrapin ◽  
Imperfect Detection ◽  
Modeling Framework ◽  
Abundance Estimates ◽  
Invasive Method ◽  
Capture Recapture ◽  
Diamondback Terrapins

Determining the population status of the diamondback terrapin (Malaclemys terrapin spp.) is challenging due to their ecology and limitations associated with traditional sampling methods. Visual counting of emergent heads offers a promising, efficient, and non-invasive method for generating abundance estimates of terrapin populations across broader spatial scales than has been achieved using capture–recapture, and can be used to quantify determinants of spatial variation in abundance. We conducted repeated visual head count surveys along the shoreline of Wellfleet Bay in Wellfleet, Massachusetts, and analyzed the count data using a hierarchical modeling framework designed specifically for repeated count data: the N-mixture model. This approach allows for simultaneous modeling of imperfect detection to generate estimates of true terrapin abundance. Detection probability was lowest when temperatures were coldest and when wind speed was highest. Local abundance was on average higher in sheltered sites compared to exposed sites and declined over the course of the sampling season. We demonstrate the utility of pairing visual head counts and N-mixture models as an efficient method for estimating terrapin abundance and show how the approach can be used to identifying environmental factors that influence detectability and distribution.

scholarly journals Visual Head Counts: A Promising Method for Efficient Monitoring of Diamondback Terrapins

2019 ◽  
Author(s):  
Patricia Levasseur ◽  
Sean Sterrett ◽  
Chris Sutherland
Keyword(s):  
Count Data ◽  
Hierarchical Modeling ◽  
Spatial Scales ◽  
Promising Method ◽  
Diamondback Terrapin ◽  
Imperfect Detection ◽  
Modeling Framework ◽  
Abundance Estimates ◽  
Diamondback Terrapins ◽  
And Behavior

Generating a range-wide population status of the diamondback terrapin (Malaclemys terrapin spp.) is challenging due to a combination of species ecology and behavior, and limitations associated with traditional sampling methods. Visual counting of emergent heads offers an efficient, non-invasive and promising method for generating abundance estimates of terrapin populations across broader spatial scales and can be used to explain spatial variation in population size. We conducted repeated visual head count surveys at 38 predetermined sites along the shoreline of Wellfleet Bay in Wellfleet, Massachusetts. We analyzed the count data using a hierarchical modeling framework designed specifically to analyze repeated count data: the so-called N-mixture model. This approach allows for simultaneous modeling of imperfect detection to generate estimates of true terrapin abundance. We found detection probability was lowest when skies were overcast and when wind speed was highest. Site specific abundance varied but we found that abundance estimates were, on average, higher in unexposed sites compared to exposed sites. We demonstrate the utility of pairing visual head counts and N-mixture models as an efficient method for estimating terrapin abundance and show how the approach can be used to identifying environmental factors that influence detectability and distribution.

scholarly journals Using areas of known occupancy to identify sources of variation in detection probability of raptors: taking time lowers replication effort for surveys

2016 ◽  
Vol 3 (10) ◽  
pp. 160368 ◽  
Author(s):  
Campbell Murn ◽  
Graham J. Holloway
Keyword(s):  
Detection Probability ◽  
Spatial Scales ◽  
Survey Methods ◽  
A Priori ◽  
Low Density ◽  
Occupancy Models ◽  
Imperfect Detection ◽  
Factors Affecting ◽  
Sources Of Variation ◽  
Time Of Year

Species occurring at low density can be difficult to detect and if not properly accounted for, imperfect detection will lead to inaccurate estimates of occupancy. Understanding sources of variation in detection probability and how they can be managed is a key part of monitoring. We used sightings data of a low-density and elusive raptor (white-headed vulture Trigonoceps occipitalis ) in areas of known occupancy (breeding territories) in a likelihood-based modelling approach to calculate detection probability and the factors affecting it. Because occupancy was known a priori to be 100%, we fixed the model occupancy parameter to 1.0 and focused on identifying sources of variation in detection probability. Using detection histories from 359 territory visits, we assessed nine covariates in 29 candidate models. The model with the highest support indicated that observer speed during a survey, combined with temporal covariates such as time of year and length of time within a territory, had the highest influence on the detection probability. Averaged detection probability was 0.207 (s.e. 0.033) and based on this the mean number of visits required to determine within 95% confidence that white-headed vultures are absent from a breeding area is 13 (95% CI: 9–20). Topographical and habitat covariates contributed little to the best models and had little effect on detection probability. We highlight that low detection probabilities of some species means that emphasizing habitat covariates could lead to spurious results in occupancy models that do not also incorporate temporal components. While variation in detection probability is complex and influenced by effects at both temporal and spatial scales, temporal covariates can and should be controlled as part of robust survey methods. Our results emphasize the importance of accounting for detection probability in occupancy studies, particularly during presence/absence studies for species such as raptors that are widespread and occur at low densities.

scholarly journals Using a capture-recapture approach for modelling the detectability and distribution of Houbara Bustard in southern Tunisia

2011 ◽  
Vol 22 (3) ◽  
pp. 288-298 ◽  
Author(s):  
M. CHAMMEM ◽  
S. SELMI ◽  
T. KHORCHANI ◽  
S. NOUIRA
Keyword(s):  
Regression Analyses ◽  
Species Occurrence ◽  
Imperfect Detection ◽  
Southern Tunisia ◽  
Species Of Conservation Concern ◽  
Habitat Factors ◽  
Houbara Bustard ◽  
Capture Recapture ◽  
Conservation Concern ◽  
Free Ranging

SummaryModelling the distribution of species of conservation concern is an important issue in population ecology. Classically, logistic regression analyses are conducted to estimate species’ distributions from detection/non-detection data in a sample of sites and to test for the significance of several environmental variables in predicting the probability of occurrence. These modelling approaches assume that species detection probability is constant and equals one in all sampled sites, which is critical, notably in the case of rare, shy and cryptic species. The capture-recapture-like approach developed by Mackenzie et al. (2002, 2003) provides a reliable tool that accounts for imperfect detection when estimating species occurrence, as well as for assessing the relevance of site features as predictors of species occurrence probability. The aim of this study was to explore the possibility of using this approach in the context of Houbara Bustard Chlamydotis undulata in southern Tunisia. Our results show once more the low detectability of this emblematic species and stress the need to take this factor into account when estimating Houbara spatial distribution. The distribution of Houbara in southern Tunisia is more likely to be shaped by human-related than by habitat factors. In particular, Houbara occurrence was positively associated with site remoteness and camel numbers. Houbara seemed to avoid areas with high human presence and shared the most remote and agriculture-free zones with free-ranging camels.

scholarly journals Uncertainty estimation in heterogeneous capture–recapture count data

2017 ◽  
Vol 87 (10) ◽  
pp. 2094-2114 ◽  
Author(s):  
Orasa Anan ◽  
Dankmar Böhning ◽  
Antonello Maruotti
Keyword(s):  
Count Data ◽  
Uncertainty Estimation ◽  
Capture Recapture

scholarly journals School learning climate in the lens of parental involvement and school leadership: lessons for inclusiveness among public schools

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Jason Alinsunurin
Keyword(s):  
Public Schools ◽  
School Improvement ◽  
Parental Involvement ◽  
School Leadership ◽  
Hierarchical Modeling ◽  
Substantial Reduction ◽  
Learning Climate ◽  
Modeling Framework ◽  
Research Attention ◽  
School Learning

Abstract Prior literature has shown that school learning climate is critical in helping individual learners meet their educational objectives. In this paper, the role of parental involvement in shaping the school learning climate is explored within a multilevel and hierarchical modeling framework using data from the 2015 PISA round. As the schools’ social and relational character, we find that reducing learning barriers is a critical challenge for school leadership. A welcoming environment for parents, as well as the effective design of effective forms of two-way communications, are positively associated with a substantial reduction in the barriers to improving teacher management’s learning climate. We also find that public schools facing social and educational inclusiveness challenges can dramatically enhance their learning environment by activating specific parental involvement mechanisms. Similarly, principal’s leadership in framing and communicating goals and curricular development to the school is also found to be significant for inclusiveness. However, parental involvement is also found to have potential tensions with school management. The worsening of the learning climate may arise due to pressures brought about by laws requiring parental involvement in schools. Because the learning climate is composed of a wide variety of relationships between and within schools, this work demonstrates that parental involvement is an integral part of school leadership and the school improvement process. Further research attention is encouraged to understand the tensions between teacher roles, principal leadership, and parental involvement through employing other quantitative or qualitative research designs.

Multiple challenges confront a high-effort inland recreational fishery in decline

2018 ◽  
Vol 75 (9) ◽  
pp. 1357-1368 ◽  
Author(s):  
Christopher L. Cahill ◽  
Stephanie Mogensen ◽  
Kyle L. Wilson ◽  
Ariane Cantin ◽  
R. Nilo Sinnatamby ◽  
...  
Keyword(s):  
Multiple Stressors ◽  
Fishing Effort ◽  
Population Declines ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Abundance Estimates ◽  
Sampling Locations ◽  
Management Perspective ◽  
Capture Recapture ◽  
Multiple Challenges ◽  
High Effort

Catch-and-release regulations designed to protect fisheries may fail to halt population declines, particularly in situations where fishing effort is high and when multiple stressors threaten a population. We demonstrate this claim using Alberta’s Bow River, which supports a high-effort rainbow trout (Oncorhynchus mykiss) fishery where anglers voluntarily release >99% of their catch. We examined the population trend of adult trout, which were tagged and recaptured using electrofishing surveys conducted intermittently during 2003–2013. We constructed Bayesian multisession capture–recapture models in Stan to obtain abundance estimates for trout and regressed trend during two periods to account for variation in sampling locations. General patterns from all models indicated the population declined throughout the study. Potential stressors to this system that may have contributed to the decline include whirling disease (Myxobolus cerebralis), which was detected for the first time in 2016, notable floods, and release mortality. Because disease and floods are largely uncontrollable from a management perspective, we suggest that stringent tactics such as angler effort restrictions may be necessary to maintain similar fisheries.

Osmoregulation in the Diamondback Terrapin, Malaclemys Terrapin Centrata

1967 ◽  
Vol 46 (1) ◽  
pp. 161-167 ◽  
Author(s):  
P. J. BENTLEY ◽  
W. L. BRETZ ◽  
KNUT SCHMIDT-NIELSEN
Keyword(s):  
Fresh Water ◽  
Solute Concentration ◽  
Diamondback Terrapin ◽  
Malaclemys Terrapin ◽  
Excess Sodium ◽  
Diamondback Terrapins ◽  
Do So

1. While in hypertonic environment diamondback terrapins (Malaclemys centrata) slowly lose water by osmosis through the integument and as urine through the kidney. 2. Small amounts of sodium are gained, probably largely as a result of diffusion through the integument rather than by drinking, and this sodium is principally excreted extrarenally. Nevertheless, the solute concentration in the blood of such turtles increases. 3. When returned to fresh water the animals rehydrate and excrete accumulated excess sodium. 4. In these ways they could undoubtedly survive for extended periods in the absence of fresh water, but it is not clear whether they could do so indefinitely.

scholarly journals On the Estimation of Dispersal and Movement of Birds

The Condor ◽  
2004 ◽  
Vol 106 (4) ◽  
pp. 720-731 ◽  
Author(s):  
William L. Kendall ◽  
James D. Nichols
Keyword(s):  
Robust Design ◽  
Nonlinear Dynamic ◽  
Detection Probability ◽  
Cross Correlation ◽  
Statistical Methodology ◽  
Open Population ◽  
Abundance Estimates ◽  
Capture Recapture ◽  
Over Time

Abstract The estimation of dispersal and movement is important to evolutionary and population ecologists, as well as to wildlife managers. We review statistical methodology available to estimate movement probabilities. We begin with cases where individual birds can be marked and their movements estimated with the use of multisite capture-recapture methods. Movements can be monitored either directly, using telemetry, or by accounting for detection probability when conventional marks are used. When one or more sites are unobservable, telemetry, band recoveries, incidental observations, a closed- or open-population robust design, or partial determinism in movements can be used to estimate movement. When individuals cannot be marked, presence-absence data can be used to model changes in occupancy over time, providing indirect inferences about movement. Where abundance estimates over time are available for multiple sites, potential coupling of their dynamics can be investigated using linear cross-correlation or nonlinear dynamic tools. Sobre la Estimación de la Dispersión y el Movimiento de las Aves Resumen. La estimación de la dispersión y el movimiento es importante para los ecó logos evolutivos y de poblaciones, así como también para los encargados del manejo de vida silvestre. Revisamos la metodología estadística disponible para estimar probabilidades de movimiento. Empezamos con casos donde aves individuales pueden ser marcadas y sus movimientos estimados con el uso de métodos de captura-repactura para múltiples sitios. Los movimientos pueden ser monitoreados ya sea directamente, usando telemetría o teniendo en cuenta las probabilidades de detección cuando se usan marcas convencionales. Cuando uno o más sitios no pueden ser observados, se puede estimar el movimiento usando telemetría, recuperación de anillos, observaciones circunstanciales, un diseño poblacional robusto cerrado o abierto, o determinismo parcial de los movimientos. Cuando los individuos no pueden ser marcados, se pueden usar datos de presencia-ausencia para modelar los cambios en el tiempo de la ocupación, brindando inferencias indirectas sobre los movimientos. Cuando las estimaciones de abundancia a lo largo del tiempo están disponibles para varios sitios, se puede investigar la interrelación potencial de sus dinámicas usando correlaciones cruzadas lineales o herramientas para dinámica no lineal.

scholarly journals Naive Juvenile Diamondback Terrapins: Kin Recognition in Controlled Encounter Experiments

Elements ◽  
2007 ◽  
Vol 3 (1) ◽  
Author(s):  
Brad Macdonald ◽  
Alexis Rife
Keyword(s):  
Social Behavior ◽  
Kin Selection ◽  
Kin Recognition ◽  
Diamondback Terrapin ◽  
Malaclemys Terrapin ◽  
Selection Theory ◽  
Boston College ◽  
Diamondback Terrapins ◽  
Existing Data

Northern diamondback terrapin (<span style="font-family: mceinline;"><em>malaclemys terrapin</em>) turtle </span>hatchlings raised as part of a laboratory headstarting program are the focus of kin recognition studies taking place at Boston College. Experiments examining basking behaviors in 13 trials of familiar kin and 11 trials of unfamiliar non-kin. Familiar kin averaged more aggressive engagements per trial (2.44 vs. 0.36), more displacements per trial (13.36 vs. 3.91), and more instances of climbing on one another (13.36 vs. 2.36). Familiar kin basked in congregations more frequently per trial than unfamiliar non-kin. These data suggest that diamondback terrapins treat each other differently based on either kinship or familiarity-or both. Further research will be conducted on familiar and unfamiliar kin and non-kin groupings to help elucidate the existing data by determining which variable has greater consequence and if Hamilton's kin selection theory can be applied to terrapin juvenile social behavior.

Predicting fish species richness and habitat relationships using Bayesian hierarchical multispecies occupancy models

2020 ◽  
Vol 77 (3) ◽  
pp. 602-610
Author(s):  
Shannon White ◽  
Evan Faulk ◽  
Caleb Tzilkowski ◽  
Andrew Weber ◽  
Matthew Marshall ◽  
...  
Keyword(s):  
Species Richness ◽  
Fish Community ◽  
Fish Assemblages ◽  
Similar Species ◽  
Occupancy Models ◽  
Imperfect Detection ◽  
Modeling Framework ◽  
Bayesian Hierarchical ◽  
Recreation Area ◽  
Species Occupancy

Understanding how stream fishes respond to changes in habitat availability is complicated by low occurrence rates of many species, which in turn reduces the ability to quantify species–habitat relationships and account for imperfect detection in estimates of species richness. Multispecies occupancy models have been used sparingly in the analysis of fisheries data, but address the aforementioned deficiencies by allowing information to be shared among ecologically similar species, thereby enabling species–habitat relationships to be estimated for entire fish communities, including rare species. Here, we highlight the utility of hierarchical multispecies occupancy models for the analysis of fish community data and demonstrate the modeling framework on a stream fish community dataset collected in the Delaware Water Gap National Recreation Area, USA. In particular, we demonstrate the ability of the modeling framework to make inferences at the species-, guild-, and community-levels, thereby making it a powerful tool for understanding and predicting how environmental variables influence species occupancy probabilities and structure fish assemblages.

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