A Terrestrial Furbearer Estimator Based on Probability Sampling

Becker, Earl F.

doi:10.2307/3809525

Cited by 48 publications

(43 citation statements)

References 23 publications

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“…The LIS technique entails the establishment of a baseline (projected x-axis) and several parallel transects extending perpendicular to the baseline (projected y-axis) (Becker 1991). Researchers follow these transects and count the tracks that were intersected by the subject animal.…”

Section: Population Estimationmentioning

confidence: 99%

“…Firstly, for estimating the abundance of macaques in a large area, we developed a ground-based track counting method by applying the line-intercept sampling (LIS) technique (Becker 1991;VanSickle and Lindzey 1991;Fattorini and Marcheselli 2002). The LIS technique is one of the probability sampling techniques used for estimating the abundance of a subject species by counting the animal tracks (i.e., set of footprints) that intersect with line transects in a survey area.…”

Section: Introductionmentioning

confidence: 99%

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Estimation of abundance and distribution of Japanese macaques using track counts in snow

Enari

Sakamaki

2011

Acta Theriol

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We introduced a technique based on groundbased track counts in snow for simultaneously estimating the abundance and distribution of Japanese macaques Macaca fuscata (Blyth, 1875) and evaluated its efficiency by conducting a field trial in northern Japan. Within the 50-km 2 area, we selected five transects with consideration of the spatial distribution of vegetation, local climate, and geographical conditions contained in the entire area. Five trained researchers recorded the track counts three times in those geolocations that intersected with each transect. We estimated the macaque abundance by the line-intercept sampling (LIS) technique using the number of tracks and predicted its distribution by ecological-niche factor analysis (ENFA) using the tracks as a proof of macaques' presence. We confirmed that the LIS-based technique could yield reasonably accurate estimates of the number of individuals and troops, compared with the population estimates of macaques based on the home-range method. We successfully used ENFA in constructing a macaque distribution model that had a high predictive performance; this was verified by comparing the predicted macaque distribution with the actual use of habitat obtained by tracking radiotagged troops in the study area.

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Section: Population Estimationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Estimation of abundance and distribution of Japanese macaques using track counts in snow

Enari

Sakamaki

2011

Acta Theriol

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“…Sampling probabilities are estimated from the distribution of tracks relative to the sampling design. These techniques have been effective for sparsely distributed animals that can be readily tracked on snow [14,15].…”

Section: Classical Probability Samplingmentioning

confidence: 99%

Abundance: Population Size and Density Estimation

Udevitz

Gould

2012

Encyclopedia of Environmetrics

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Estimates of population size (total number of individuals) or density (number of individuals per unit area) are some of the most basic requirements for wildlife research and management. This article provides a brief overview of approaches for wildlife population estimation. These include habitat‐based approaches such as quadrat, line intercept, distance, and repeated count methods, as well as animal‐based approaches such as capture–recapture and harvest methods. In contrast to methods that only index changes in these parameters, estimates of size or density must account for the probability that an individual will be included in the sample used for estimation. The essential differences in the approaches are in how the samples are obtained and how the sampling probabilities are estimated.

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“…Instead, managers have relied on indirect measures of relative abundance, such as harvest statistics and catch-per-unit-effort, or have conducted extensive radiotelemetry studies to estimate densities (Rausch 1967, Roughton and Sweeny 1982, Fuller and Snow 1988, Burch et al 2005). More recently, transect intercept probability sampling and the sampling unit probability estimator (SUPE), which use the probability of observing track networks in the snow (Becker 1991, Van Sickle and Lindzey 1991, Becker et al 1998, Patterson et al 2004, have been used because they are efficient for extremely large study areas (!10,000 km 2 ), do not rely on collared animals, and provide confidence intervals (Becker et al 1998). However, these approaches are not feasible in areas where track networks cannot be followed continuously from aircraft due to heavy forest cover.…”

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confidence: 99%

Simulating carnivore movements: An occupancy–abundance relationship for surveying wolves

Webb

Merrill

2012

Wildlife Society Bulletin

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Where carnivore species exist at low densities, are cryptic, and inhabit forested habitats where detection is low, survey approaches commonly rely on observation of tracks. Recent advances in probability sampling for aerial surveys of track networks in snow show promise for improving density estimates, but they are not applicable when continuously following a track network is not possible. Occupancy-abundance modeling is an alternative survey approach for wide-ranging carnivores, but past models may not be appropriate when using tracks because tracks of one individual or group of individuals may extend across several survey units. We derived an occupancy-abundance relationship by simulating the intersection of wolf (Canis lupus) travel paths and survey grid cells for a range of wolf-pack densities. Wolf movement paths were simulated using a habitat-biased, correlated random walk movement model using step lengths and turning angles of 17 Global Positioning System (GPS)-collared wolves in west-central Alberta, Canada. We estimated occupancy levels for a range of pack densities found in North America and found that pack density was linearly related to the proportion of occupied survey units. Concurrent movement paths of 5 GPS-collared wolf packs were used to evaluate the model predictions. While the model overestimated the number of packs by 33%, the difference translated into only 13 wolves across the study area. We discuss improvements for continued development of occupancy surveys as a potential method to determine carnivore abundance where other approaches are not feasible. ß 2012 The Wildlife Society.

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A Terrestrial Furbearer Estimator Based on Probability Sampling

Cited by 48 publications

References 23 publications

Estimation of abundance and distribution of Japanese macaques using track counts in snow

Estimation of abundance and distribution of Japanese macaques using track counts in snow

Abundance: Population Size and Density Estimation

Simulating carnivore movements: An occupancy–abundance relationship for surveying wolves

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