Walruses from space: walrus counts in simultaneous remotely piloted aircraft system versus very high-resolution satellite imagery
Regular counts of walruses (Odobenus rosmarus) across their pan-Arctic range are necessary to determine accurate population trends and in turn understand how current rapid changes in their habitat, such as sea ice loss, are impacting them. However, surveying a region as vast and remote as the Arctic...
Published in: | Remote Sensing in Ecology and Conservation |
---|---|
Main Authors: | , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Wiley
2024
|
Subjects: | |
Online Access: | http://nora.nerc.ac.uk/id/eprint/535967/ https://nora.nerc.ac.uk/id/eprint/535967/1/Remote%20Sens%20Ecol%20Conserv%20-%202024%20-%20Cubaynes%20-%20Walruses%20from%20space%20%20walrus%20counts%20in%20simultaneous%20remotely%20piloted%20aircraft.pdf https://zslpublications.onlinelibrary.wiley.com/doi/full/10.1002/rse2.391 |
id |
ftnerc:oai:nora.nerc.ac.uk:535967 |
---|---|
record_format |
openpolar |
spelling |
ftnerc:oai:nora.nerc.ac.uk:535967 2024-06-23T07:50:20+00:00 Walruses from space: walrus counts in simultaneous remotely piloted aircraft system versus very high-resolution satellite imagery Cubaynes, Hannah C. Forcada, Jaume Kovacs, Kit M. Lydersen, Christian Downie, Rod Fretwell, Peter T. 2024-05-21 text http://nora.nerc.ac.uk/id/eprint/535967/ https://nora.nerc.ac.uk/id/eprint/535967/1/Remote%20Sens%20Ecol%20Conserv%20-%202024%20-%20Cubaynes%20-%20Walruses%20from%20space%20%20walrus%20counts%20in%20simultaneous%20remotely%20piloted%20aircraft.pdf https://zslpublications.onlinelibrary.wiley.com/doi/full/10.1002/rse2.391 en eng Wiley https://nora.nerc.ac.uk/id/eprint/535967/1/Remote%20Sens%20Ecol%20Conserv%20-%202024%20-%20Cubaynes%20-%20Walruses%20from%20space%20%20walrus%20counts%20in%20simultaneous%20remotely%20piloted%20aircraft.pdf Cubaynes, Hannah C. orcid:0000-0002-9497-154X Forcada, Jaume orcid:0000-0002-2115-0150 Kovacs, Kit M.; Lydersen, Christian; Downie, Rod; Fretwell, Peter T. orcid:0000-0002-1988-5844 . 2024 Walruses from space: walrus counts in simultaneous remotely piloted aircraft system versus very high-resolution satellite imagery. Remote Sensing in Ecology and Conservation. 13, pp. https://doi.org/10.1002/rse2.391 <https://doi.org/10.1002/rse2.391> Publication - Article PeerReviewed 2024 ftnerc https://doi.org/10.1002/rse2.391 2024-06-04T23:53:02Z Regular counts of walruses (Odobenus rosmarus) across their pan-Arctic range are necessary to determine accurate population trends and in turn understand how current rapid changes in their habitat, such as sea ice loss, are impacting them. However, surveying a region as vast and remote as the Arctic with vessels or aircraft is a formidable logistical challenge, limiting the frequency and spatial coverage of field surveys. An alternative methodology involving very high-resolution (VHR) satellite imagery has proven to be a useful tool to detect walruses, but the feasibility of accurately counting individuals has not been addressed. Here, we compare walrus counts obtained from a VHR WorldView-3 satellite image, with a simultaneous ground count obtained using a remotely piloted aircraft system (RPAS). We estimated the accuracy of the walrus counts depending on (1) the spatial resolution of the VHR satellite imagery, providing the same WorldView-3 image to assessors at three different spatial resolutions (i.e., 50, 30 and 15 cm per pixel) and (2) the level of expertise of the assessors (experts vs. a mixed level of experience – representative of citizen scientists). This latter aspect of the study is important to the efficiency and outcomes of the global assessment programme because there are citizen science campaigns inviting the public to count walruses in VHR satellite imagery. There were 73 walruses in our RPAS ‘control’ image. Our results show that walruses were under-counted in VHR satellite imagery at all spatial resolutions and across all levels of assessor expertise. Counts from the VHR satellite imagery with 30 cm spatial resolution were the most accurate and least variable across levels of expertise. This was a successful first attempt at validating VHR counts with near-simultaneous, in situ, data but further assessments are required for walrus aggregations with different densities and configurations, on different substrates. Article in Journal/Newspaper Arctic Odobenus rosmarus Sea ice walrus* Natural Environment Research Council: NERC Open Research Archive Arctic Remote Sensing in Ecology and Conservation |
institution |
Open Polar |
collection |
Natural Environment Research Council: NERC Open Research Archive |
op_collection_id |
ftnerc |
language |
English |
description |
Regular counts of walruses (Odobenus rosmarus) across their pan-Arctic range are necessary to determine accurate population trends and in turn understand how current rapid changes in their habitat, such as sea ice loss, are impacting them. However, surveying a region as vast and remote as the Arctic with vessels or aircraft is a formidable logistical challenge, limiting the frequency and spatial coverage of field surveys. An alternative methodology involving very high-resolution (VHR) satellite imagery has proven to be a useful tool to detect walruses, but the feasibility of accurately counting individuals has not been addressed. Here, we compare walrus counts obtained from a VHR WorldView-3 satellite image, with a simultaneous ground count obtained using a remotely piloted aircraft system (RPAS). We estimated the accuracy of the walrus counts depending on (1) the spatial resolution of the VHR satellite imagery, providing the same WorldView-3 image to assessors at three different spatial resolutions (i.e., 50, 30 and 15 cm per pixel) and (2) the level of expertise of the assessors (experts vs. a mixed level of experience – representative of citizen scientists). This latter aspect of the study is important to the efficiency and outcomes of the global assessment programme because there are citizen science campaigns inviting the public to count walruses in VHR satellite imagery. There were 73 walruses in our RPAS ‘control’ image. Our results show that walruses were under-counted in VHR satellite imagery at all spatial resolutions and across all levels of assessor expertise. Counts from the VHR satellite imagery with 30 cm spatial resolution were the most accurate and least variable across levels of expertise. This was a successful first attempt at validating VHR counts with near-simultaneous, in situ, data but further assessments are required for walrus aggregations with different densities and configurations, on different substrates. |
format |
Article in Journal/Newspaper |
author |
Cubaynes, Hannah C. Forcada, Jaume Kovacs, Kit M. Lydersen, Christian Downie, Rod Fretwell, Peter T. |
spellingShingle |
Cubaynes, Hannah C. Forcada, Jaume Kovacs, Kit M. Lydersen, Christian Downie, Rod Fretwell, Peter T. Walruses from space: walrus counts in simultaneous remotely piloted aircraft system versus very high-resolution satellite imagery |
author_facet |
Cubaynes, Hannah C. Forcada, Jaume Kovacs, Kit M. Lydersen, Christian Downie, Rod Fretwell, Peter T. |
author_sort |
Cubaynes, Hannah C. |
title |
Walruses from space: walrus counts in simultaneous remotely piloted aircraft system versus very high-resolution satellite imagery |
title_short |
Walruses from space: walrus counts in simultaneous remotely piloted aircraft system versus very high-resolution satellite imagery |
title_full |
Walruses from space: walrus counts in simultaneous remotely piloted aircraft system versus very high-resolution satellite imagery |
title_fullStr |
Walruses from space: walrus counts in simultaneous remotely piloted aircraft system versus very high-resolution satellite imagery |
title_full_unstemmed |
Walruses from space: walrus counts in simultaneous remotely piloted aircraft system versus very high-resolution satellite imagery |
title_sort |
walruses from space: walrus counts in simultaneous remotely piloted aircraft system versus very high-resolution satellite imagery |
publisher |
Wiley |
publishDate |
2024 |
url |
http://nora.nerc.ac.uk/id/eprint/535967/ https://nora.nerc.ac.uk/id/eprint/535967/1/Remote%20Sens%20Ecol%20Conserv%20-%202024%20-%20Cubaynes%20-%20Walruses%20from%20space%20%20walrus%20counts%20in%20simultaneous%20remotely%20piloted%20aircraft.pdf https://zslpublications.onlinelibrary.wiley.com/doi/full/10.1002/rse2.391 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic Odobenus rosmarus Sea ice walrus* |
genre_facet |
Arctic Odobenus rosmarus Sea ice walrus* |
op_relation |
https://nora.nerc.ac.uk/id/eprint/535967/1/Remote%20Sens%20Ecol%20Conserv%20-%202024%20-%20Cubaynes%20-%20Walruses%20from%20space%20%20walrus%20counts%20in%20simultaneous%20remotely%20piloted%20aircraft.pdf Cubaynes, Hannah C. orcid:0000-0002-9497-154X Forcada, Jaume orcid:0000-0002-2115-0150 Kovacs, Kit M.; Lydersen, Christian; Downie, Rod; Fretwell, Peter T. orcid:0000-0002-1988-5844 . 2024 Walruses from space: walrus counts in simultaneous remotely piloted aircraft system versus very high-resolution satellite imagery. Remote Sensing in Ecology and Conservation. 13, pp. https://doi.org/10.1002/rse2.391 <https://doi.org/10.1002/rse2.391> |
op_doi |
https://doi.org/10.1002/rse2.391 |
container_title |
Remote Sensing in Ecology and Conservation |
_version_ |
1802641211600666624 |