Divergent estimates of herd‐wide caribou calf survival: Ecological factors and methodological biases
Abstract Population monitoring is a critical part of effective wildlife management, but methods are prone to biases that can hinder our ability to accurately track changes in populations through time. Calf survival plays an important role in ungulate population dynamics and can be monitored using te...
Published in: | Ecology and Evolution |
---|---|
Main Authors: | , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Wiley
2020
|
Subjects: | |
Online Access: | https://doi.org/10.1002/ece3.6553 https://doaj.org/article/c1881de9b3314eea98c664e06a1ce648 |
id |
ftdoajarticles:oai:doaj.org/article:c1881de9b3314eea98c664e06a1ce648 |
---|---|
record_format |
openpolar |
spelling |
ftdoajarticles:oai:doaj.org/article:c1881de9b3314eea98c664e06a1ce648 2023-05-15T17:22:02+02:00 Divergent estimates of herd‐wide caribou calf survival: Ecological factors and methodological biases E. Hance Ellington Keith P. Lewis Erin L. Koen Eric Vander Wal 2020-08-01T00:00:00Z https://doi.org/10.1002/ece3.6553 https://doaj.org/article/c1881de9b3314eea98c664e06a1ce648 EN eng Wiley https://doi.org/10.1002/ece3.6553 https://doaj.org/toc/2045-7758 2045-7758 doi:10.1002/ece3.6553 https://doaj.org/article/c1881de9b3314eea98c664e06a1ce648 Ecology and Evolution, Vol 10, Iss 15, Pp 8476-8505 (2020) composition surveys mortality risk multiple imputation Newfoundland survival analysis woodland caribou (Rangifer tarandus caribou) Ecology QH540-549.5 article 2020 ftdoajarticles https://doi.org/10.1002/ece3.6553 2022-12-31T05:24:39Z Abstract Population monitoring is a critical part of effective wildlife management, but methods are prone to biases that can hinder our ability to accurately track changes in populations through time. Calf survival plays an important role in ungulate population dynamics and can be monitored using telemetry and herd composition surveys. These methods, however, are susceptible to unrepresentative sampling and violations of the assumption of equal detectability, respectively. Here, we capitalized on 55 herd‐wide estimates of woodland caribou (Rangifer tarandus caribou) calf survival in Newfoundland, Canada, using telemetry (n = 1,175 calves) and 249 herd‐wide estimates of calf:cow ratios (C:C) using herd composition surveys to investigate these potential biases. These data included 17 herd‐wide estimates replicated from both methods concurrently (n = 448 calves and n = 17 surveys) which we used to understand which processes and sampling biases contributed to disagreement between estimates of herd‐wide calf survival. We used Cox proportional hazards models to determine whether estimates of calf mortality risk were biased by the date a calf was collared. We also used linear mixed‐effects models to determine whether estimates of C:C ratios were biased by survey date and herd size. We found that calves collared later in the calving season had a higher mortality risk and that C:C tended to be higher for surveys conducted later in the autumn. When we used these relationships to modify estimates of herd‐wide calf survival derived from telemetry and herd composition surveys concurrently, we found that formerly disparate estimates of woodland caribou calf survival now overlapped (within a 95% confidence interval) in a majority of cases. Our case study highlights the potential of under‐appreciated biases to impact our understanding of population dynamics and suggests ways that managers can limit the influence of these biases in the two widely applied methods for estimating herd‐wide survival. Article in Journal/Newspaper Newfoundland Rangifer tarandus Directory of Open Access Journals: DOAJ Articles Canada Ecology and Evolution 10 15 8476 8505 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
composition surveys mortality risk multiple imputation Newfoundland survival analysis woodland caribou (Rangifer tarandus caribou) Ecology QH540-549.5 |
spellingShingle |
composition surveys mortality risk multiple imputation Newfoundland survival analysis woodland caribou (Rangifer tarandus caribou) Ecology QH540-549.5 E. Hance Ellington Keith P. Lewis Erin L. Koen Eric Vander Wal Divergent estimates of herd‐wide caribou calf survival: Ecological factors and methodological biases |
topic_facet |
composition surveys mortality risk multiple imputation Newfoundland survival analysis woodland caribou (Rangifer tarandus caribou) Ecology QH540-549.5 |
description |
Abstract Population monitoring is a critical part of effective wildlife management, but methods are prone to biases that can hinder our ability to accurately track changes in populations through time. Calf survival plays an important role in ungulate population dynamics and can be monitored using telemetry and herd composition surveys. These methods, however, are susceptible to unrepresentative sampling and violations of the assumption of equal detectability, respectively. Here, we capitalized on 55 herd‐wide estimates of woodland caribou (Rangifer tarandus caribou) calf survival in Newfoundland, Canada, using telemetry (n = 1,175 calves) and 249 herd‐wide estimates of calf:cow ratios (C:C) using herd composition surveys to investigate these potential biases. These data included 17 herd‐wide estimates replicated from both methods concurrently (n = 448 calves and n = 17 surveys) which we used to understand which processes and sampling biases contributed to disagreement between estimates of herd‐wide calf survival. We used Cox proportional hazards models to determine whether estimates of calf mortality risk were biased by the date a calf was collared. We also used linear mixed‐effects models to determine whether estimates of C:C ratios were biased by survey date and herd size. We found that calves collared later in the calving season had a higher mortality risk and that C:C tended to be higher for surveys conducted later in the autumn. When we used these relationships to modify estimates of herd‐wide calf survival derived from telemetry and herd composition surveys concurrently, we found that formerly disparate estimates of woodland caribou calf survival now overlapped (within a 95% confidence interval) in a majority of cases. Our case study highlights the potential of under‐appreciated biases to impact our understanding of population dynamics and suggests ways that managers can limit the influence of these biases in the two widely applied methods for estimating herd‐wide survival. |
format |
Article in Journal/Newspaper |
author |
E. Hance Ellington Keith P. Lewis Erin L. Koen Eric Vander Wal |
author_facet |
E. Hance Ellington Keith P. Lewis Erin L. Koen Eric Vander Wal |
author_sort |
E. Hance Ellington |
title |
Divergent estimates of herd‐wide caribou calf survival: Ecological factors and methodological biases |
title_short |
Divergent estimates of herd‐wide caribou calf survival: Ecological factors and methodological biases |
title_full |
Divergent estimates of herd‐wide caribou calf survival: Ecological factors and methodological biases |
title_fullStr |
Divergent estimates of herd‐wide caribou calf survival: Ecological factors and methodological biases |
title_full_unstemmed |
Divergent estimates of herd‐wide caribou calf survival: Ecological factors and methodological biases |
title_sort |
divergent estimates of herd‐wide caribou calf survival: ecological factors and methodological biases |
publisher |
Wiley |
publishDate |
2020 |
url |
https://doi.org/10.1002/ece3.6553 https://doaj.org/article/c1881de9b3314eea98c664e06a1ce648 |
geographic |
Canada |
geographic_facet |
Canada |
genre |
Newfoundland Rangifer tarandus |
genre_facet |
Newfoundland Rangifer tarandus |
op_source |
Ecology and Evolution, Vol 10, Iss 15, Pp 8476-8505 (2020) |
op_relation |
https://doi.org/10.1002/ece3.6553 https://doaj.org/toc/2045-7758 2045-7758 doi:10.1002/ece3.6553 https://doaj.org/article/c1881de9b3314eea98c664e06a1ce648 |
op_doi |
https://doi.org/10.1002/ece3.6553 |
container_title |
Ecology and Evolution |
container_volume |
10 |
container_issue |
15 |
container_start_page |
8476 |
op_container_end_page |
8505 |
_version_ |
1766108258820423680 |