Transect width and missed observations in counting muskoxen (Ovibos moschatus) from fixed-wing aircraft
While conductioning muskox-censuses (Ovibos moschatus) in winter in Jameson Land, NE Greenland, from a fixed-wing aircraft, we examined the width of transects covered. We used a laser range-finder binocular for measuring the distance to observed groups. We found that 1000 m was a reasonable limit fo...
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Language: | English |
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Septentrio Academic Publishing
1993
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Online Access: | https://septentrio.uit.no/index.php/rangifer/article/view/1096 https://doi.org/10.7557/2.13.2.1096 |
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ftunitroemsoe:oai:ojs.henry.ub.uit.no:article/1096 2023-05-15T16:27:57+02:00 Transect width and missed observations in counting muskoxen (Ovibos moschatus) from fixed-wing aircraft Aastrup, P. Mosbech, A. 1993-12-01 application/pdf https://septentrio.uit.no/index.php/rangifer/article/view/1096 https://doi.org/10.7557/2.13.2.1096 eng eng Septentrio Academic Publishing https://septentrio.uit.no/index.php/rangifer/article/view/1096/1043 https://septentrio.uit.no/index.php/rangifer/article/view/1096 doi:10.7557/2.13.2.1096 Copyright (c) 2015 P. Aastrup, A. Mosbech http://creativecommons.org/licenses/by/3.0/ CC-BY Rangifer; Årg 13 Nr 2 (1993); 99-104 Rangifer; Vol 13 No 2 (1993); 99-104 1890-6729 muskox census techniques Ovibos Greenland info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 1993 ftunitroemsoe https://doi.org/10.7557/2.13.2.1096 2021-08-16T14:49:07Z While conductioning muskox-censuses (Ovibos moschatus) in winter in Jameson Land, NE Greenland, from a fixed-wing aircraft, we examined the width of transects covered. We used a laser range-finder binocular for measuring the distance to observed groups. We found that 1000 m was a reasonable limit for observing a high proportion of the muskoxen present even though it was possible to observe muskoxen from 4000 m or even more. Using two observers on the right side of the aircraft each speaking into a tape recorder with an automatic time signal, we recorded observations and performed a double-observer experiment. By matching the group sizes and perpendicular distances with times of observation we could compare observations of the two observers. We found that both observers missed up to 25% of muskoxen within a 2000 m transect width. The main reasons for missing animals is difficulty in obtaining reference points in snow covered landscape and fatigue of the observers. Calibration of estimated distances using read-outs from the laser-range finder is an adequate method of obtaining distance data for line transect calculations. Our double-observer experiment demonstrated that even groups close to the transect are easily missed. Article in Journal/Newspaper Greenland muskox ovibos moschatus Rangifer University of Tromsø: Septentrio Academic Publishing Greenland Jameson Land ENVELOPE(-23.500,-23.500,71.167,71.167) Rangifer 13 3 99 |
institution |
Open Polar |
collection |
University of Tromsø: Septentrio Academic Publishing |
op_collection_id |
ftunitroemsoe |
language |
English |
topic |
muskox census techniques Ovibos Greenland |
spellingShingle |
muskox census techniques Ovibos Greenland Aastrup, P. Mosbech, A. Transect width and missed observations in counting muskoxen (Ovibos moschatus) from fixed-wing aircraft |
topic_facet |
muskox census techniques Ovibos Greenland |
description |
While conductioning muskox-censuses (Ovibos moschatus) in winter in Jameson Land, NE Greenland, from a fixed-wing aircraft, we examined the width of transects covered. We used a laser range-finder binocular for measuring the distance to observed groups. We found that 1000 m was a reasonable limit for observing a high proportion of the muskoxen present even though it was possible to observe muskoxen from 4000 m or even more. Using two observers on the right side of the aircraft each speaking into a tape recorder with an automatic time signal, we recorded observations and performed a double-observer experiment. By matching the group sizes and perpendicular distances with times of observation we could compare observations of the two observers. We found that both observers missed up to 25% of muskoxen within a 2000 m transect width. The main reasons for missing animals is difficulty in obtaining reference points in snow covered landscape and fatigue of the observers. Calibration of estimated distances using read-outs from the laser-range finder is an adequate method of obtaining distance data for line transect calculations. Our double-observer experiment demonstrated that even groups close to the transect are easily missed. |
format |
Article in Journal/Newspaper |
author |
Aastrup, P. Mosbech, A. |
author_facet |
Aastrup, P. Mosbech, A. |
author_sort |
Aastrup, P. |
title |
Transect width and missed observations in counting muskoxen (Ovibos moschatus) from fixed-wing aircraft |
title_short |
Transect width and missed observations in counting muskoxen (Ovibos moschatus) from fixed-wing aircraft |
title_full |
Transect width and missed observations in counting muskoxen (Ovibos moschatus) from fixed-wing aircraft |
title_fullStr |
Transect width and missed observations in counting muskoxen (Ovibos moschatus) from fixed-wing aircraft |
title_full_unstemmed |
Transect width and missed observations in counting muskoxen (Ovibos moschatus) from fixed-wing aircraft |
title_sort |
transect width and missed observations in counting muskoxen (ovibos moschatus) from fixed-wing aircraft |
publisher |
Septentrio Academic Publishing |
publishDate |
1993 |
url |
https://septentrio.uit.no/index.php/rangifer/article/view/1096 https://doi.org/10.7557/2.13.2.1096 |
long_lat |
ENVELOPE(-23.500,-23.500,71.167,71.167) |
geographic |
Greenland Jameson Land |
geographic_facet |
Greenland Jameson Land |
genre |
Greenland muskox ovibos moschatus Rangifer |
genre_facet |
Greenland muskox ovibos moschatus Rangifer |
op_source |
Rangifer; Årg 13 Nr 2 (1993); 99-104 Rangifer; Vol 13 No 2 (1993); 99-104 1890-6729 |
op_relation |
https://septentrio.uit.no/index.php/rangifer/article/view/1096/1043 https://septentrio.uit.no/index.php/rangifer/article/view/1096 doi:10.7557/2.13.2.1096 |
op_rights |
Copyright (c) 2015 P. Aastrup, A. Mosbech http://creativecommons.org/licenses/by/3.0/ |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.7557/2.13.2.1096 |
container_title |
Rangifer |
container_volume |
13 |
container_issue |
3 |
container_start_page |
99 |
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1766017557342453760 |