Age structure in a newly established and increasing population: initially high proportion of young birds among nesting Great Grey Owls
Abstract The mechanisms behind expansions of the distribution of a bird species and the ensuing establishment of new populations are poorly known. The distribution of Great Grey Owl ( Strix nebulosa ) in the western Palearctic has generally expanded towards southwest during the past fifty years, and...
Published in: | Journal of Ornithology |
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Springer Science and Business Media LLC
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Online Access: | http://dx.doi.org/10.1007/s10336-020-01809-1 https://link.springer.com/content/pdf/10.1007/s10336-020-01809-1.pdf https://link.springer.com/article/10.1007/s10336-020-01809-1/fulltext.html |
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crspringernat:10.1007/s10336-020-01809-1 2023-05-15T16:11:50+02:00 Age structure in a newly established and increasing population: initially high proportion of young birds among nesting Great Grey Owls Sonerud, Geir A. Solheim, Roar Berg, Trond Norwegian University of Life Sciences 2020 http://dx.doi.org/10.1007/s10336-020-01809-1 https://link.springer.com/content/pdf/10.1007/s10336-020-01809-1.pdf https://link.springer.com/article/10.1007/s10336-020-01809-1/fulltext.html en eng Springer Science and Business Media LLC https://creativecommons.org/licenses/by/4.0 https://creativecommons.org/licenses/by/4.0 CC-BY Journal of Ornithology volume 162, issue 1, page 109-118 ISSN 2193-7192 2193-7206 journal-article 2020 crspringernat https://doi.org/10.1007/s10336-020-01809-1 2022-01-04T16:38:00Z Abstract The mechanisms behind expansions of the distribution of a bird species and the ensuing establishment of new populations are poorly known. The distribution of Great Grey Owl ( Strix nebulosa ) in the western Palearctic has generally expanded towards southwest during the past fifty years, and particularly so in Fennoscandia. In the past decade, the recorded breeding population in Norway, confined to Hedmark county bordering Sweden, increased from 1 pair in 2009 to > 100 pairs in 2017–2018, extending the southwestern border of the distribution > 100 km. We studied the age structure of this expanding population based on the molting pattern of the wing feathers of birds captured at the nest site for banding and of non-captured birds photographed in flight. In Fennoscandia the Great Grey Owl relies on shrews and microtine rodents, which usually fluctuate in 3–4 years cycles. The proportion of 1-year old birds among the nesting Great Grey Owls was higher in peak year two of each small mammal population cycle (2011, 2014 and 2018) than in peak year one (2010, 2013 and 2017), and was particularly high (77%) in 2011 when the owl population was far lower (22 nestings recorded) than in later corresponding years (64 nestings in 2014 and 103 in 2018). Thus, this population seems to have been founded to a large extent by birds nesting as 1 year olds, and most likely having dispersed from Sweden. The ability to determine the age of Great Grey Owls without having to capture them extended our data set, in particular for males, which are more reluctant to attack intruders at the nest site and, therefore, less likely to be captured for banding. Being able to age a bird without having to capture it is important, because trapping does not sample a bird population randomly. Article in Journal/Newspaper Fennoscandia great grey owl Strix nebulosa Springer Nature (via Crossref) Norway Journal of Ornithology 162 1 109 118 |
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Springer Nature (via Crossref) |
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crspringernat |
language |
English |
description |
Abstract The mechanisms behind expansions of the distribution of a bird species and the ensuing establishment of new populations are poorly known. The distribution of Great Grey Owl ( Strix nebulosa ) in the western Palearctic has generally expanded towards southwest during the past fifty years, and particularly so in Fennoscandia. In the past decade, the recorded breeding population in Norway, confined to Hedmark county bordering Sweden, increased from 1 pair in 2009 to > 100 pairs in 2017–2018, extending the southwestern border of the distribution > 100 km. We studied the age structure of this expanding population based on the molting pattern of the wing feathers of birds captured at the nest site for banding and of non-captured birds photographed in flight. In Fennoscandia the Great Grey Owl relies on shrews and microtine rodents, which usually fluctuate in 3–4 years cycles. The proportion of 1-year old birds among the nesting Great Grey Owls was higher in peak year two of each small mammal population cycle (2011, 2014 and 2018) than in peak year one (2010, 2013 and 2017), and was particularly high (77%) in 2011 when the owl population was far lower (22 nestings recorded) than in later corresponding years (64 nestings in 2014 and 103 in 2018). Thus, this population seems to have been founded to a large extent by birds nesting as 1 year olds, and most likely having dispersed from Sweden. The ability to determine the age of Great Grey Owls without having to capture them extended our data set, in particular for males, which are more reluctant to attack intruders at the nest site and, therefore, less likely to be captured for banding. Being able to age a bird without having to capture it is important, because trapping does not sample a bird population randomly. |
author2 |
Norwegian University of Life Sciences |
format |
Article in Journal/Newspaper |
author |
Sonerud, Geir A. Solheim, Roar Berg, Trond |
spellingShingle |
Sonerud, Geir A. Solheim, Roar Berg, Trond Age structure in a newly established and increasing population: initially high proportion of young birds among nesting Great Grey Owls |
author_facet |
Sonerud, Geir A. Solheim, Roar Berg, Trond |
author_sort |
Sonerud, Geir A. |
title |
Age structure in a newly established and increasing population: initially high proportion of young birds among nesting Great Grey Owls |
title_short |
Age structure in a newly established and increasing population: initially high proportion of young birds among nesting Great Grey Owls |
title_full |
Age structure in a newly established and increasing population: initially high proportion of young birds among nesting Great Grey Owls |
title_fullStr |
Age structure in a newly established and increasing population: initially high proportion of young birds among nesting Great Grey Owls |
title_full_unstemmed |
Age structure in a newly established and increasing population: initially high proportion of young birds among nesting Great Grey Owls |
title_sort |
age structure in a newly established and increasing population: initially high proportion of young birds among nesting great grey owls |
publisher |
Springer Science and Business Media LLC |
publishDate |
2020 |
url |
http://dx.doi.org/10.1007/s10336-020-01809-1 https://link.springer.com/content/pdf/10.1007/s10336-020-01809-1.pdf https://link.springer.com/article/10.1007/s10336-020-01809-1/fulltext.html |
geographic |
Norway |
geographic_facet |
Norway |
genre |
Fennoscandia great grey owl Strix nebulosa |
genre_facet |
Fennoscandia great grey owl Strix nebulosa |
op_source |
Journal of Ornithology volume 162, issue 1, page 109-118 ISSN 2193-7192 2193-7206 |
op_rights |
https://creativecommons.org/licenses/by/4.0 https://creativecommons.org/licenses/by/4.0 |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.1007/s10336-020-01809-1 |
container_title |
Journal of Ornithology |
container_volume |
162 |
container_issue |
1 |
container_start_page |
109 |
op_container_end_page |
118 |
_version_ |
1765997033276047360 |