Estimating detection probabilities of tagged fish migrating past fixed receiver stations using only local information

2010 ◽  
Vol 67 (4) ◽  
pp. 641-658 ◽  
Author(s):  
Michael C. Melnychuk ◽  
Carl J. Walters

We developed a method to predict the probability of detecting acoustic tags crossing a receiver station using only detection information at that station. This method is suitable for acoustic or radio telemetry studies in which individually tagged animals migrate past fixed stations (where a station may consist of one or more receivers). It is based on fitting attenuation models to sequences of detections and missed transmissions of individually coded tags in fish migrating past stations of the Pacific Ocean Shelf Tracking Project (POST). We used estimated attenuation model parameters from detected fish at each station to predict the number of fish that crossed the station undetected, which in turn was used to calculate the local detection probability. This estimator was correlated (r = 0.54–0.81 in river and coastal habitats) with mark–recapture estimates of detection probability (pmr) that use nonlocal detection information at stations further along migration routes. This local detection probability estimate can be used as a covariate of pmr in mark–recapture models and can predict approximate values of pmr at final detection stations where pmr is not estimable because of the lack of recaptures further along migration routes.

<i>Abstract</i>.—A common assumption in acoustic or radio telemetry studies is that tag transmission strength is homogeneous for a particular tag type, which in turn supports the assumption that detection ranges or mark–recapture detection probabilities are homogenous among tagged fish. Variation among tags in acoustic intensity could reduce precision in detection probability estimates that do not account for it, and therefore possibly in the precision of survival or abundance estimates. Simple methods are suggested for quantifying variation in tag strength prior to tagging fish and incorporating these measurements into mark–recapture models. At little extra effort to the researcher, these measurements could explain part of the variation in detection probability estimates and therefore could increase the precision of survival or abundance estimates of migrating fish. This potential source of variation in detection probabilities was investigated in a case study with migrating salmon smolts. An index of tag strength was quantified while coded acoustic tags were activated prior to tagging fish. Detection and survival probabilities were estimated with standard mark–recapture methods for the downstream and early ocean migration. A model that included the tag strength index as an additive covariate of detection probabilities had a reasonable level of support compared to a model without the index, suggesting that this source of variation should not be ignored.


2018 ◽  
Vol 45 (5) ◽  
pp. 446 ◽  
Author(s):  
John D. Willson ◽  
Shannon E. Pittman ◽  
Jeffrey C. Beane ◽  
Tracey D. Tuberville

Context Accurate estimates of population density are a critical component of effective wildlife conservation and management. However, many snake species are so secretive that their density cannot be determined using traditional methods such as capture–mark–recapture. Thus, the status of most terrestrial snake populations remains completely unknown. Aim We developed a novel simulation-based technique for estimating density of secretive snakes that combined behavioural observations of snake road-crossing behaviour (crossing speed), effort-corrected road-survey data, and simulations of spatial movement patterns derived from radio-telemetry, without relying on mark–recapture. Methods We used radio-telemetry data to parameterise individual-based movement models that estimate the frequency with which individual snakes cross roads and used information on survey vehicle speed and snake crossing speed to determine the probability of detecting a snake, given that it crosses the road transect during a survey. Snake encounter frequencies during systematic road surveys were then interpreted in light of detection probabilities and simulation model results to estimate snake densities and to assess various factors likely to affect abundance estimates. We demonstrated the broad applicability of this approach through a case study of the imperiled southern hognose snake (Heterodon simus) in the North Carolina (USA) Sandhills. Key results We estimated that H. simus occurs at average densities of 0.17 ha–1 in the North Carolina Sandhills and explored the sensitivity of this estimate to assumptions and variation in model parameters. Conclusions Our novel method allowed us to generate the first abundance estimates for H. simus. We found that H. simus exists at low densities relative to congeners and other mid-sized snake species, raising concern that this species may not only have declined in geographic range, but may also occur at low densities or be declining in their strongholds, such as the North Carolina Sandhills. Implications We present a framework for estimating density of species that have traditionally been considered too secretive to study at the population level. This method will greatly enhance our ability to study and manage a wide variety of snake species and could be applied to other secretive wildlife species that are most frequently encountered during road surveys.


2009 ◽  
Vol 60 (12) ◽  
pp. 1231 ◽  
Author(s):  
Michael C. Melnychuk

Mark–recapture models for estimating survival and detection probabilities of tagged animals that migrate past successive receiver stations can incorporate multiple, linked stocks to improve detection probability estimates. When multiple release groups are analysed in a common framework, detection information can be shared to compensate for small sample sizes and provide generality beyond single-stock approaches. Methods for structuring complex detection history data and applying standard mark–recapture models are presented, allowing for information sharing among multiple stocks under nested migration route structures, where some portions of routes are shared with other stocks and other portions are unique. Possible biases from split-route migration patterns within a release group are described, along with a simple method of correcting these biases using stock-specific parameters that incorporate movement probabilities. Environmental covariates can be paired with stock-specific run timing data to model stock-specific detection probabilities that change seasonally. Finally, a method for assessing the redundancy of receivers on a multiple-receiver detection line is described, based on considerations of receiver line geometry. Examples are drawn from detection data of juvenile salmon on the Pacific Ocean Shelf Tracking Project (POST) array, but the methods presented here are transferable to other systems.


2005 ◽  
Vol 32 (3) ◽  
pp. 211 ◽  
Author(s):  
Gary C. White

One of the most pervasive uses of indices of wildlife populations is uncorrected counts of animals. Two examples are the minimum number known alive from capture and release studies, and aerial surveys where the detection probability is not estimated from a sightability model, marked animals, or distance sampling. Both the mark–recapture and distance-sampling estimators are techniques to estimate the probability of detection of an individual animal (or cluster of animals), which is then used to correct a count of animals. However, often the number of animals in a survey is inadequate to compute an estimate of the detection probability and hence correct the count. Modern methods allow sophisticated modelling to estimate the detection probability, including incorporating covariates to provide additional information about the detection probability. Examples from both distance and mark–recapture sampling are presented to demonstrate the approach.


2021 ◽  
Vol 11 (5) ◽  
pp. 2198
Author(s):  
Junwoo Jung ◽  
Jaesung Lim ◽  
Sungyeol Park ◽  
Haengik Kang ◽  
Seungbok Kwon

A frequency hopping orthogonal frequency division multiple access (FH-OFDMA) can provide low probability of detection (LPD) and anti-jamming capabilities to users against adversary detectors. To obtain an extreme LPD capability that cannot be provided by the basic symbol-by-symbol (SBS)-based FH pattern, we proposed two FH patterns, namely chaotic standard map (CSM) and cat map for FH-OFDMA systems. In our previous work, through analysis of complexity to regenerate the transmitted symbol sequence, at the point of adversary detectors, we found that the CSM had a lower probability of intercept than the cat map and SBS. It is possible when a detector already knows symbol and frame structures, and the detector has been synchronized to the FH-OFDMA system. Unlike the previous work, here, we analyze whether the CSM provides greater LPD capability than the cat map and SBS by detection probability using spectrum sensing technique. We analyze the detection probability of the CSM and provide detection probabilities of the cat map and SBS compared to the CSM. Based on our analysis of the detection probability and numerical results, it is evident that the CSM provides greater LPD capability than both the cat map and SBS-based FH-OFDMA systems.


2020 ◽  
Vol 7 (1) ◽  
pp. 1-8
Author(s):  
Camille Bégin Marchand ◽  
André Desrochers ◽  
Junior A. Tremblay ◽  
Pascal Côté

AbstractMigration routes vary greatly among small passerine species and populations. It is now possible to determine the routes over great distances and long periods of time with emerging monitoring networks. We tracked individual Swainson’s Thrush (Catharus ustulatus), Bicknell’s Thrush (Catharus bicknelli) and Gray-cheeked Thrush (Catharus minimus) in northeastern Quebec and compared their migration routes and paces across an array of radio-telelemetry stations in North America. Swainson’s Thrush migrated further inland than the other two species. Individuals from all three species slowed their migration pace in the southeastern United States, and Swainson’s Thrush was more likely to stopover than Bicknell’s Thrush. Although individuals were tagged in a small area within or close to their breeding range, the results document the variability of migration routes between species with similar ecological characteristics and provide detailed material to be used for migration studies with broader taxonomic or ecological scope.


2006 ◽  
Vol 3 (3) ◽  
pp. 819-857
Author(s):  
N. B. Yenigül ◽  
A.T. Hendsbergen ◽  
A. M. M. Elfeki ◽  
F. M. Dekking

Abstract. Contaminant leaks released from landfills are a significant threat to groundwater quality. The groundwater detection monitoring systems installed in the vicinity of such facilities are vital. In this study the detection probability of a contaminant plume released from a landfill has been investigated by means of both a simulation and an analytical model for both homogeneous and heterogeneous aquifer conditions. The results of the two models are compared for homogeneous aquifer conditions to illustrate the errors that might be encountered with the simulation model. For heterogeneous aquifer conditions contaminant transport is modelled by an analytical model using effective (macro) dispersivities. The results of the analysis show that the simulation model gives the concentration values correctly over most of the plume length for homogeneous aquifer conditions, and that the detection probability of a contaminant plume at given monitoring well locations match quite well. For heterogeneous aquifer conditions the approximating analytical model based on effective (macro) dispersivities yields the average concentration distribution satisfactorily. However, it is insufficient in monitoring system design since the discrepancy between the detection probabilities of contaminant plumes at given monitoring well locations computed by the two models is significant, particularly with high dispersivity and heterogeneity.


The Auk ◽  
2000 ◽  
Vol 117 (3) ◽  
pp. 748-759 ◽  
Author(s):  
Caleb E. Gordon

Abstract I used mark-recapture analysis and radio telemetry to characterize winter movement patterns of six grassland sparrows in southeastern Arizona. Mark-recapture data were generated by banding birds captured during repeated flush-netting sessions conducted on a series of 7-ha plots over three consecutive winters. This resulted in 2,641 captures of 2,006 individual sparrows of the six species. Radio telemetry was conducted concurrently on 20 individuals of four of these species. Recapture data and radio telemetry indicated that Cassin's Sparrow (Aimophila cassinii) and Grasshopper Sparrow (Ammodramus savannarum) were the most sedentary, followed by Baird's Sparrow (Ammodramus bairdii), Vesper Sparrow (Pooecetes gramineus), Savannah Sparrow (Passerculus sandwichensis), and Brewer's Sparrow (Spizella breweri). Grasshopper, Baird's, Savannah, and Vesper sparrows tended to remain within fixed home ranges during winter. With the exception of Savannah Sparrows, whose movement behavior varied among study sites, movement patterns remained constant within species across years and study sites despite radical fluctuations in the absolute and relative abundances of all species. Interspecific differences in movement pattern suggest that species in this system partition niche space according to the regional-coexistence mechanism. Abundances of the most sedentary species, Cassin's, Grasshopper, and Baird's sparrows, were poorly or negatively correlated with summer rainfall at the between-year landscape scale, whereas abundances of the more mobile Savannah, Vesper, and Brewer's sparrows were strongly positively correlated. This is consistent with the theoretical prediction that movement constrains large-scale habitat selection, favoring mobile species in fragmented environments.


The Auk ◽  
2007 ◽  
Vol 124 (3) ◽  
pp. 815-827
Author(s):  
Leesa A. Sidhu ◽  
Edward A. Catchpole ◽  
Peter Dann

Abstract We analyzed yearly mark-recapture-recovery information collected over a 36-year period for the Little Penguins (Eudyptula minor) of Phillip Island in southeastern Australia. We show that it is feasible to model age-dependence for the survival, recapture, and recovery probabilities simultaneously, and that such a modeling scheme yields biologically realistic age structures for the model parameters. We provide illustrations of potentially erroneous results that may arise when researchers fail (1) to consider simultaneous age-dependence or (2) to detect annual variations that may mask age-dependence. From 1968 to 2004, 23,686 chicks were flipper-banded; 2,979 birds were encountered after fledging, and 1,347 were ultimately recovered dead. We found low survival of 17% in the first year of life, increasing to 71% in the second year of life, 78% in the third year, and 83% thereafter, and declining gradually after nine years of age. A population model allowing for immigration of birds from areas surrounding the study sites fits the observed stable population in the study sites. Modelado de Marca-Recaptura-Recuperación y Supervivencia Relacionada con la Edad en Eudyptula minor


Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3198
Author(s):  
Flavio Alexander Asurza-Véliz ◽  
Waldo Sven Lavado-Casimiro

This study presents a methodology for the regional parameters estimation of the SWAT (Soil and Water Assessment Tool) model, with the objective of estimating daily flow series in the Pacific drainage under the context of limited hydrological data availability. This methodology has been designed to obtain the model parameters from a limited number of basins (14) to finally regionalize them to basins without hydrological data based on physical-climatic characteristics. In addition, the bootstrapping method was selected to estimate the uncertainty associated with the parameters set selection in the regionalization process. In general, the regionalized parameters reduce the initial underestimation which is reflected in a better quantification of daily flows, and improve the low flows performance. Furthermore, the results show that the SWAT model correctly represents the water balance and seasonality of the hydrological cycle main components. However, the model does not correctly quantify the high flows rates during wet periods. These findings provide supporting information for studies of water balance and water management on the Peruvian Pacific drainage. The approach and methods developed can be replicated in any other region of Peru.


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