Visibility Bias during Aerial Surveys of Elk in Northcentral Idaho

Samuel, Michael D.; Garton, Edward O.; Schlegel, Michael; Carson, Robert G.

doi:10.2307/3801280

Cited by 177 publications

(263 citation statements)

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“…Where u. is the multiple linear regression equation on factors influencing carcass removal (Samuel et al 1987, Unsworth et al 1999): H= b 0 + bixi+b 2 x 2 + .. .bkX k…”

Section: Discussionmentioning

confidence: 99%

“…The contributing variables determined through logistic regression were used to create sightability models (Samuel et al 1987). These models allow one to estimate targets that would be missed during searches due removal by scavengers prior to searches.…”

Section: Discussionmentioning

confidence: 99%

“…The significant relationships identified during the analysis above where then used to build predictive models. Such variable-weighted models have not yet been applied to wind farm environmental assessments, however they have been used in other studies to predict visibility bias and sightability of elk and big horn sheep (Sightability models -Samuel et al 1987;Steinhorst et al 1989;Unsworth et 21 al. 1990;Otten et al 1993;Bodie et al 1995;Anderson et al 1998;Noyes et al 2000).…”

Section: Analytical Techniquesmentioning

confidence: 99%

“…Negative coefficients indicate that larger values of that variable cause scavenging likelihood to decrease, whereas positive coefficients cause scavenging likelihood to increase (Samuel et al 1987). Using this to calculate the probability of scavenging (see Methods), experimenters should be able to adjust numbers of carcasses observed to compensate for biases in detection due to removal of carcasses by scavengers.…”

Section: Significant Variable Modelmentioning

confidence: 99%

“…It is extremely important, therefore, to understand to what degree each variable affects searcher efficiency. Even though these correction factors have not been used yet in wind farm assessment, studies have been conducted in other areas which create variable-weighted models in order to predict realistic numbers of importance (Samuel et al 1987;Steinhorst et al 1989;Unsworth et al 1990;Otten et al 1993;Bodie et al 1995;Anderson et al 1998;Noyes et al 2000).…”

Section: Introductionmentioning

confidence: 99%

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Determining factors affecting carcass removal and searching efficiency during the post-construction monitoring of wind farms.

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“…Where u. is the multiple linear regression equation on factors influencing carcass removal (Samuel et al 1987, Unsworth et al 1999): H= b 0 + bixi+b 2 x 2 + .. .bkX k…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Analytical Techniquesmentioning

confidence: 99%

Section: Significant Variable Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Determining factors affecting carcass removal and searching efficiency during the post-construction monitoring of wind farms.

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A new double observer‐based census framework to improve abundance estimations in mountain ungulates and other gregarious species with a reduced effort

Panaccio,

Brambilla,

Bassano

et al. 2024

Ecol Sol and Evidence

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Estimating animal abundance has a key role to play in ecology and conservation, but survey methods are always challenged by imperfect detection. Among the techniques applied to deal with this issue, Double Observer (DO) is increasing in popularity due to its cost‐effectiveness. However, the effort of using DO for surveying large territories can be significant. A DO‐based survey method that allows accurate abundance estimations with reduced effort would increase the applicability of the method. This would have positive effects on the conservation of species which are challenging to survey such as mountain ungulates. We used computer simulations based on real data and a field test to assess the reliability of the DO and of a new proposed survey procedure, the Double Observer Adjusted Survey (DOAS). DOAS is based on total block counts adjusted with some DO surveys conducted in a proportion of the total area only. Such DO surveys are then used to estimate detection probability with a mark‐recapture‐derived approach. We found that full DO is much more accurate than simple block counts for abundance estimations. DOAS is a less demanding alternative to full DO and can produce comparable abundance estimates, at the cost of a slightly lower precision. However, in the DOAS overall detectability has to be estimated within a sufficient number of sites (around a quarter of the total) to obtain a higher precision and avoid large overestimations. Practical implications. DO methods could increase the reliability of abundance estimations in mountain ungulates and other gregarious species. Full DO in particular could allow researchers to obtain unbiased estimations with high precision and its usage is therefore suggested instead of block counts in wildlife monitoring. Given the high costs of full DO, the DOAS procedure could be a viable and cost‐effective survey strategy to improve abundance estimates when resources are scarce.

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Monitoring for Reintroductions

Nichols

Armstrong

2012

Reintroduction Biology

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Visibility Bias during Aerial Surveys of Elk in Northcentral Idaho

Cited by 177 publications

References 0 publications

Determining factors affecting carcass removal and searching efficiency during the post-construction monitoring of wind farms.

Determining factors affecting carcass removal and searching efficiency during the post-construction monitoring of wind farms.

A new double observer‐based census framework to improve abundance estimations in mountain ungulates and other gregarious species with a reduced effort

Monitoring for Reintroductions

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