Density estimates of unmarked mammals: comparing two models and assumptions across multiple species and years
Density estimation is a key goal in ecology, but accurate estimates for unmarked animals remain elusive. Camera trap data can bridge this gap, but accuracy, precision, and concordance varies among estimators. We compared estimates from unmarked spatial capture–recapture (spatial count (SC)) models,...
Published in: | Canadian Journal of Zoology |
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2024
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Online Access: | http://dx.doi.org/10.1139/cjz-2023-0055 https://cdnsciencepub.com/doi/full-xml/10.1139/cjz-2023-0055 https://cdnsciencepub.com/doi/pdf/10.1139/cjz-2023-0055 |
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crcansciencepubl:10.1139/cjz-2023-0055 2024-04-07T07:51:49+00:00 Density estimates of unmarked mammals: comparing two models and assumptions across multiple species and years Fisher, J.T. Dickie, M. Burgar, J.M. Burton, A.C. Serrouya, R. Regional Industry Caribou Collaboration 2024 http://dx.doi.org/10.1139/cjz-2023-0055 https://cdnsciencepub.com/doi/full-xml/10.1139/cjz-2023-0055 https://cdnsciencepub.com/doi/pdf/10.1139/cjz-2023-0055 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Zoology volume 102, issue 3, page 286-297 ISSN 0008-4301 1480-3283 Animal Science and Zoology Ecology, Evolution, Behavior and Systematics journal-article 2024 crcansciencepubl https://doi.org/10.1139/cjz-2023-0055 2024-03-08T00:37:33Z Density estimation is a key goal in ecology, but accurate estimates for unmarked animals remain elusive. Camera trap data can bridge this gap, but accuracy, precision, and concordance varies among estimators. We compared estimates from unmarked spatial capture–recapture (spatial count (SC)) models, and time in front of camera (TIFC) models, for four large mammal species in boreal Canada. Species differed in movement rates, behaviours, and sociality—traits related to model assumptions. TIFC densities typically exceeded SC model estimates for all species. Two- to five-fold differences between estimators were common. SC estimates were annually stable for moose and caribou but not for white-tailed deer. TIFC estimates showed high annual variation in some species, sites, and years, and consistency in others. Both models often produced imprecise estimates. Estimates varied from DNA- and aerial survey-based estimates. We contend models diverge, or implausibly vary, due to violations of model assumptions incurred by animal behaviour. Gregarious animals pose challenges to SC, whereas curious animals pose challenges for TIFC models. Simulations can help unravel the role of assumption violations in affecting accuracy of estimates, but field applications across species and landscapes help interpret the outcomes of estimating density from simulated data. Article in Journal/Newspaper caribou Canadian Science Publishing Canada Canadian Journal of Zoology |
institution |
Open Polar |
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Canadian Science Publishing |
op_collection_id |
crcansciencepubl |
language |
English |
topic |
Animal Science and Zoology Ecology, Evolution, Behavior and Systematics |
spellingShingle |
Animal Science and Zoology Ecology, Evolution, Behavior and Systematics Fisher, J.T. Dickie, M. Burgar, J.M. Burton, A.C. Serrouya, R. Density estimates of unmarked mammals: comparing two models and assumptions across multiple species and years |
topic_facet |
Animal Science and Zoology Ecology, Evolution, Behavior and Systematics |
description |
Density estimation is a key goal in ecology, but accurate estimates for unmarked animals remain elusive. Camera trap data can bridge this gap, but accuracy, precision, and concordance varies among estimators. We compared estimates from unmarked spatial capture–recapture (spatial count (SC)) models, and time in front of camera (TIFC) models, for four large mammal species in boreal Canada. Species differed in movement rates, behaviours, and sociality—traits related to model assumptions. TIFC densities typically exceeded SC model estimates for all species. Two- to five-fold differences between estimators were common. SC estimates were annually stable for moose and caribou but not for white-tailed deer. TIFC estimates showed high annual variation in some species, sites, and years, and consistency in others. Both models often produced imprecise estimates. Estimates varied from DNA- and aerial survey-based estimates. We contend models diverge, or implausibly vary, due to violations of model assumptions incurred by animal behaviour. Gregarious animals pose challenges to SC, whereas curious animals pose challenges for TIFC models. Simulations can help unravel the role of assumption violations in affecting accuracy of estimates, but field applications across species and landscapes help interpret the outcomes of estimating density from simulated data. |
author2 |
Regional Industry Caribou Collaboration |
format |
Article in Journal/Newspaper |
author |
Fisher, J.T. Dickie, M. Burgar, J.M. Burton, A.C. Serrouya, R. |
author_facet |
Fisher, J.T. Dickie, M. Burgar, J.M. Burton, A.C. Serrouya, R. |
author_sort |
Fisher, J.T. |
title |
Density estimates of unmarked mammals: comparing two models and assumptions across multiple species and years |
title_short |
Density estimates of unmarked mammals: comparing two models and assumptions across multiple species and years |
title_full |
Density estimates of unmarked mammals: comparing two models and assumptions across multiple species and years |
title_fullStr |
Density estimates of unmarked mammals: comparing two models and assumptions across multiple species and years |
title_full_unstemmed |
Density estimates of unmarked mammals: comparing two models and assumptions across multiple species and years |
title_sort |
density estimates of unmarked mammals: comparing two models and assumptions across multiple species and years |
publisher |
Canadian Science Publishing |
publishDate |
2024 |
url |
http://dx.doi.org/10.1139/cjz-2023-0055 https://cdnsciencepub.com/doi/full-xml/10.1139/cjz-2023-0055 https://cdnsciencepub.com/doi/pdf/10.1139/cjz-2023-0055 |
geographic |
Canada |
geographic_facet |
Canada |
genre |
caribou |
genre_facet |
caribou |
op_source |
Canadian Journal of Zoology volume 102, issue 3, page 286-297 ISSN 0008-4301 1480-3283 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/cjz-2023-0055 |
container_title |
Canadian Journal of Zoology |
_version_ |
1795666897301143552 |