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...
Published in: | Rangifer |
---|---|
Main Authors: | , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Septentrio Academic Publishing
1993
|
Subjects: | |
Online Access: | https://doi.org/10.7557/2.13.2.1096 https://doaj.org/article/4b942669e670452786f3753bc153720f |
id |
ftdoajarticles:oai:doaj.org/article:4b942669e670452786f3753bc153720f |
---|---|
record_format |
openpolar |
spelling |
ftdoajarticles:oai:doaj.org/article:4b942669e670452786f3753bc153720f 2023-05-15T16:28:01+02:00 Transect width and missed observations in counting muskoxen (Ovibos moschatus) from fixed-wing aircraft P. Aastrup A. Mosbech 1993-12-01T00:00:00Z https://doi.org/10.7557/2.13.2.1096 https://doaj.org/article/4b942669e670452786f3753bc153720f EN eng Septentrio Academic Publishing https://septentrio.uit.no/index.php/rangifer/article/view/1096 https://doaj.org/toc/1890-6729 doi:10.7557/2.13.2.1096 1890-6729 https://doaj.org/article/4b942669e670452786f3753bc153720f Rangifer, Vol 13, Iss 2 (1993) muskox census techniques Ovibos Greenland Animal culture SF1-1100 article 1993 ftdoajarticles https://doi.org/10.7557/2.13.2.1096 2022-12-31T13:56:11Z 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 Directory of Open Access Journals: DOAJ Articles Greenland Jameson Land ENVELOPE(-23.500,-23.500,71.167,71.167) Rangifer 13 3 99 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
muskox census techniques Ovibos Greenland Animal culture SF1-1100 |
spellingShingle |
muskox census techniques Ovibos Greenland Animal culture SF1-1100 P. Aastrup A. Mosbech Transect width and missed observations in counting muskoxen (Ovibos moschatus) from fixed-wing aircraft |
topic_facet |
muskox census techniques Ovibos Greenland Animal culture SF1-1100 |
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 |
P. Aastrup A. Mosbech |
author_facet |
P. Aastrup A. Mosbech |
author_sort |
P. Aastrup |
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://doi.org/10.7557/2.13.2.1096 https://doaj.org/article/4b942669e670452786f3753bc153720f |
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, Vol 13, Iss 2 (1993) |
op_relation |
https://septentrio.uit.no/index.php/rangifer/article/view/1096 https://doaj.org/toc/1890-6729 doi:10.7557/2.13.2.1096 1890-6729 https://doaj.org/article/4b942669e670452786f3753bc153720f |
op_doi |
https://doi.org/10.7557/2.13.2.1096 |
container_title |
Rangifer |
container_volume |
13 |
container_issue |
3 |
container_start_page |
99 |
_version_ |
1766017625169592320 |