Integrating multiple sign types to improve occupancy estimation for inconspicuous species
Abstract Standard occupancy models enable unbiased estimation of occupancy by accounting for observation errors such as missed detections (false negatives) and, less commonly, incorrect detections (false positives). Occupancy models are fitted to data from repeated site visits in which surveyors rec...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Wiley
2023-05-01
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| Series: | Ecology and Evolution |
| Subjects: | |
| Online Access: | https://doi.org/10.1002/ece3.10019 |
| _version_ | 1797776535169531904 |
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| author | Mia R. Goldman Matthew Shinderman Mackenzie R. Jeffress Thomas J. Rodhouse Kevin T. Shoemaker |
| author_facet | Mia R. Goldman Matthew Shinderman Mackenzie R. Jeffress Thomas J. Rodhouse Kevin T. Shoemaker |
| author_sort | Mia R. Goldman |
| collection | DOAJ |
| description | Abstract Standard occupancy models enable unbiased estimation of occupancy by accounting for observation errors such as missed detections (false negatives) and, less commonly, incorrect detections (false positives). Occupancy models are fitted to data from repeated site visits in which surveyors record evidence of species presence. Use of indirect sign (e.g., scat, tracks) as evidence of presence can vastly improve survey efficiency for inconspicuous species but can also introduce additional sources of error. We developed a “multi‐sign” occupancy approach to model the detection process separately for unique sign types and used this method to improve estimates of occupancy dynamics for an inconspicuous species, the American pika (Ochotona princeps). We investigated how estimates of pika occupancy and environmental drivers differed under four increasingly realistic representations of the observation process: (1) perfect detection (commonly assumed for modeling pika occupancy), (2) standard occupancy model (single observation process without possibility of false detection), (3) multi‐sign with no false detections (non‐false positive model), and (4) multi‐sign with false detections (full model). For the multi‐sign occupancy models, we modeled the detection of each sign type (fresh scat, fresh haypiles, pika calls, and pika sightings) separately as a function of climatic and environmental covariates. Estimates of occupancy processes and inferences about environmental drivers were sensitive to different detection models. Simplified representations of the detection processes generally resulted in higher occupancy estimates and higher turnover rates than the full multi‐sign model. Environmental drivers also varied in their influence on occupancy models, where (e.g.) forb cover was estimated to more strongly influence occupancy in the full multi‐sign model than the simpler models. As has been reported previously in other contexts, unmodeled heterogeneity in the observation process can lead to biases in occupancy processes and uncertainty in the relationships between occupancy and environmental covariates. Overall, our multi‐sign approach to dynamic occupancy modeling, which accounts for spatio‐temporal variation in reliability among sign types, has strong potential to generate more realistic estimates of occupancy dynamics for inconspicuous species. |
| first_indexed | 2024-03-12T22:52:24Z |
| format | Article |
| id | doaj.art-c43cb6cde2cf476e8f9992e343a93a97 |
| institution | Directory Open Access Journal |
| issn | 2045-7758 |
| language | English |
| last_indexed | 2024-03-12T22:52:24Z |
| publishDate | 2023-05-01 |
| publisher | Wiley |
| record_format | Article |
| series | Ecology and Evolution |
| spelling | doaj.art-c43cb6cde2cf476e8f9992e343a93a972023-07-20T08:50:55ZengWileyEcology and Evolution2045-77582023-05-01135n/an/a10.1002/ece3.10019Integrating multiple sign types to improve occupancy estimation for inconspicuous speciesMia R. Goldman0Matthew Shinderman1Mackenzie R. Jeffress2Thomas J. Rodhouse3Kevin T. Shoemaker4Department of Natural Resources and Environmental Sciences University of Nevada – Reno Reno Nevada USADepartment of Natural Resources and Sustainability Oregon State University‐Cascades Bend Oregon USANevada Department of Wildlife Elko Nevada USADepartment of Natural Resources and Sustainability Oregon State University‐Cascades Bend Oregon USADepartment of Natural Resources and Environmental Sciences University of Nevada – Reno Reno Nevada USAAbstract Standard occupancy models enable unbiased estimation of occupancy by accounting for observation errors such as missed detections (false negatives) and, less commonly, incorrect detections (false positives). Occupancy models are fitted to data from repeated site visits in which surveyors record evidence of species presence. Use of indirect sign (e.g., scat, tracks) as evidence of presence can vastly improve survey efficiency for inconspicuous species but can also introduce additional sources of error. We developed a “multi‐sign” occupancy approach to model the detection process separately for unique sign types and used this method to improve estimates of occupancy dynamics for an inconspicuous species, the American pika (Ochotona princeps). We investigated how estimates of pika occupancy and environmental drivers differed under four increasingly realistic representations of the observation process: (1) perfect detection (commonly assumed for modeling pika occupancy), (2) standard occupancy model (single observation process without possibility of false detection), (3) multi‐sign with no false detections (non‐false positive model), and (4) multi‐sign with false detections (full model). For the multi‐sign occupancy models, we modeled the detection of each sign type (fresh scat, fresh haypiles, pika calls, and pika sightings) separately as a function of climatic and environmental covariates. Estimates of occupancy processes and inferences about environmental drivers were sensitive to different detection models. Simplified representations of the detection processes generally resulted in higher occupancy estimates and higher turnover rates than the full multi‐sign model. Environmental drivers also varied in their influence on occupancy models, where (e.g.) forb cover was estimated to more strongly influence occupancy in the full multi‐sign model than the simpler models. As has been reported previously in other contexts, unmodeled heterogeneity in the observation process can lead to biases in occupancy processes and uncertainty in the relationships between occupancy and environmental covariates. Overall, our multi‐sign approach to dynamic occupancy modeling, which accounts for spatio‐temporal variation in reliability among sign types, has strong potential to generate more realistic estimates of occupancy dynamics for inconspicuous species.https://doi.org/10.1002/ece3.10019American pikadetection probabilityfalse negativefalse positiveindirect signmulti‐sign |
| spellingShingle | Mia R. Goldman Matthew Shinderman Mackenzie R. Jeffress Thomas J. Rodhouse Kevin T. Shoemaker Integrating multiple sign types to improve occupancy estimation for inconspicuous species Ecology and Evolution American pika detection probability false negative false positive indirect sign multi‐sign |
| title | Integrating multiple sign types to improve occupancy estimation for inconspicuous species |
| title_full | Integrating multiple sign types to improve occupancy estimation for inconspicuous species |
| title_fullStr | Integrating multiple sign types to improve occupancy estimation for inconspicuous species |
| title_full_unstemmed | Integrating multiple sign types to improve occupancy estimation for inconspicuous species |
| title_short | Integrating multiple sign types to improve occupancy estimation for inconspicuous species |
| title_sort | integrating multiple sign types to improve occupancy estimation for inconspicuous species |
| topic | American pika detection probability false negative false positive indirect sign multi‐sign |
| url | https://doi.org/10.1002/ece3.10019 |
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