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Amburgey SM, Yackel Adams AA, Gardner B, Hostetter NJ, Siers SR, McClintock BT, Converse SJ. Evaluation of camera trap-based abundance estimators for unmarked populations. Ecol Appl 2021; 31:e02410. [PMID: 34255398 DOI: 10.1002/eap.2410] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 01/05/2021] [Accepted: 03/03/2021] [Indexed: 06/13/2023]
Abstract
Estimates of species abundance are critical to understand population processes and to assess and select management actions. However, capturing and marking individuals for abundance estimation, while providing robust information, can be economically and logistically prohibitive, particularly for species with cryptic behavior. Camera traps can be used to collect data at temporal and spatial scales necessary for estimating abundance, but the use of camera traps comes with limitations when target species are not uniquely identifiable (i.e., "unmarked"). Abundance estimation is particularly useful in the management of invasive species, with herpetofauna being recognized as some of the most pervasive and detrimental invasive vertebrate species. However, the use of camera traps for these taxa presents additional challenges with relevancy across multiple taxa. It is often necessary to use lures to attract animals in order to obtain sufficient observations, yet lure attraction can influence species' landscape use and potentially induce bias in abundance estimators. We investigated these challenges and assessed the feasibility of obtaining reliable abundance estimates using camera-trapping data on a population of invasive brown treesnakes (Boiga irregularis) in Guam. Data were collected using camera traps in an enclosed area where snakes were subject to high-intensity capture-recapture effort, resulting in presumed abundance of 116 snakes (density = 23/ha). We then applied spatial count, random encounter and staying time, space to event, and instantaneous sampling estimators to photo-capture data to estimate abundance and compared estimates to our presumed abundance. We found that all estimators for unmarked populations performed poorly, with inaccurate or imprecise abundance estimates that limit their usefulness for management in this system. We further investigated the sensitivity of these estimators to the use of lures (i.e., violating the assumption that animal behavior is unchanged by sampling) and camera density in a simulation study. Increasing the effective distances of a lure (i.e., lure attraction) and camera density both resulted in biased abundance estimates. Each estimator rarely recovered truth or suffered from convergence issues. Our results indicate that, when limited to unmarked estimators and the use of lures, camera traps alone are unlikely to produce abundance estimates with utility for brown treesnake management.
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Affiliation(s)
- S M Amburgey
- Washington Cooperative Fish and Wildlife Research Unit, School of Aquatic and Fishery Sciences, University of Washington, Seattle, Washington, 98195, USA
| | - A A Yackel Adams
- U.S. Geological Survey, Fort Collins Science Center, 2150 Centre Avenue, Building C, Fort Collins, Colorado, 80526, USA
| | - B Gardner
- School of Environmental and Forest Sciences, University of Washington, Seattle, Washington, 98195, USA
| | - N J Hostetter
- Washington Cooperative Fish and Wildlife Research Unit, School of Aquatic and Fishery Sciences, University of Washington, Seattle, Washington, 98195, USA
| | - S R Siers
- U.S. Department of Agriculture APHIS Wildlife Services National Wildlife Research Center, 233 Pangelinan Way, Barrigada, 96913, Guam
| | - B T McClintock
- Marine Mammal Laboratory, NOAA-NMFS Alaska Fisheries Science Center, Seattle, Washington, 98115, USA
| | - S J Converse
- U.S. Geological Survey, Washington Cooperative Fish and Wildlife Research Unit, School of Environmental and Forest Sciences & School of Aquatic and Fishery Sciences, University of Washington, Seattle, Washington, 98195, USA
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Amburgey SM, Miller DAW, Brand A, Dietrich A, Campbell Grant EH. Knowing your limits: estimating range boundaries and co‐occurrence zones for two competing plethodontid salamanders. Ecosphere 2019. [DOI: 10.1002/ecs2.2727] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- S. M. Amburgey
- Department of Ecosystem Sciences and Management The Pennsylvania State University University Park Pennsylvania 16802 USA
- Intercollege Graduate Ecology Program The Pennsylvania State University University Park Pennsylvania 16802 USA
| | - D. A. W. Miller
- Department of Ecosystem Sciences and Management The Pennsylvania State University University Park Pennsylvania 16802 USA
| | - A. Brand
- USGS Patuxent Wildlife Research Center SO Conte Anadromous Fish Research Center Turners Falls Massachusetts 01376 USA
| | - A. Dietrich
- USGS Patuxent Wildlife Research Center Laurel Maryland 20708 USA
| | - E. H. Campbell Grant
- USGS Patuxent Wildlife Research Center SO Conte Anadromous Fish Research Center Turners Falls Massachusetts 01376 USA
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Affiliation(s)
- E. Muths
- Fort Collins Science Center U.S. Geological Survey 2150 Centre Avenue Fort Collins Colorado 80526 USA
| | - R. D. Scherer
- Conservation Science Partners 501 Old Town Square Fort Collins Colorado 80524 USA
| | - S. M. Amburgey
- Department of Ecosystem Science and Management The Pennsylvania State University University Park Pennsylvania 16802 USA
- Intercollege Degree Program in Ecology The Pennsylvania State University University Park Pennsylvania 16802 USA
| | - P. S. Corn
- Northern Rocky Mountain Science Center U.S. Geological Survey Missoula Montana 59801 USA
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Amburgey SM, Murphy M, Chris Funk W. Phenotypic plasticity in developmental rate is insufficient to offset high tadpole mortality in rapidly drying ponds. Ecosphere 2016. [DOI: 10.1002/ecs2.1386] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- S. M. Amburgey
- Department of Biology Colorado State University Fort Collins Colorado 80523 USA
| | - M. Murphy
- Department of Biology Colorado State University Fort Collins Colorado 80523 USA
| | - W. Chris Funk
- Department of Biology, Graduate Degree Program in Ecology Colorado State University Fort Collins Colorado 80523 USA
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Funk WC, Murphy MA, Hoke KL, Muths E, Amburgey SM, Lemmon EM, Lemmon AR. Elevational speciation in action? Restricted gene flow associated with adaptive divergence across an altitudinal gradient. J Evol Biol 2015; 29:241-52. [DOI: 10.1111/jeb.12760] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 08/28/2015] [Accepted: 09/08/2015] [Indexed: 01/15/2023]
Affiliation(s)
- W. C. Funk
- Department of Biology Colorado State University Fort Collins CO USA
- Graduate Degree Program in Ecology Colorado State University Fort Collins CO USA
| | - M. A. Murphy
- Department of Ecosystem Science and Management University of Wyoming Laramie WY USA
- Program in Ecology University of Wyoming Laramie WY USA
| | - K. L. Hoke
- Department of Biology Colorado State University Fort Collins CO USA
| | - E. Muths
- U.S. Geological Survey Fort Collins Science Center Fort Collins CO USA
| | - S. M. Amburgey
- Department of Ecosystem Science and Management Pennsylvania State University University Park PA USA
- Intercollege Graduate Degree Program in Ecology Pennsylvania State University University Park PA USA
| | - E. M. Lemmon
- Department of Biology Florida State University Tallahassee FL USA
| | - A. R. Lemmon
- Department of Scientific Computing Florida State University Tallahassee FL USA
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