Data from: Numbers and distribution of the Great Cormorant in Iceland: limitation at the regional and metapopulation level
We studied a metapopulation of great cormorant (Phalacrocorax carbo) in Iceland, using complete aerial censuses of nests in 25 years during 1975–2015. Age composition was estimated in 1998–2014 by ground surveys in September and February. Brood size was estimated from aerial photographs in 2007–2015...
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ftdans:oai:easy.dans.knaw.nl:easy-dataset:125863 2023-07-02T03:32:43+02:00 Data from: Numbers and distribution of the Great Cormorant in Iceland: limitation at the regional and metapopulation level Gardarsson, Arnthor Jonsson, Jon Einar 2019-03-19T13:19:34.000+01:00 http://nbn-resolving.org/urn:nbn:nl:ui:13-p0-14h3 https://easy.dans.knaw.nl/ui/datasets/id/easy-dataset:125863 unknown doi:10.5061/dryad.mt5q8m2/1 doi:10.1002/ece3.5028 http://nbn-resolving.org/urn:nbn:nl:ui:13-p0-14h3 doi:10.5061/dryad.mt5q8m2 https://easy.dans.knaw.nl/ui/datasets/id/easy-dataset:125863 OPEN_ACCESS: The data are archived in Easy, they are accessible elsewhere through the DOI https://dans.knaw.nl/en/about/organisation-and-policy/legal-information/DANSLicence.pdf Life sciences medicine and health care 2019 ftdans https://doi.org/10.5061/dryad.mt5q8m2/110.1002/ece3.502810.5061/dryad.mt5q8m2 2023-06-13T13:38:21Z We studied a metapopulation of great cormorant (Phalacrocorax carbo) in Iceland, using complete aerial censuses of nests in 25 years during 1975–2015. Age composition was estimated in 1998–2014 by ground surveys in September and February. Brood size was estimated from aerial photographs in 2007–2015. Weather, food, breeding habitat, and density were considered as explanatory variables when examining numerical and distributional changes in the cormorant metapopulation. In 1975–1990 total nest numbers changed little, very low numbers about 1992 were followed by an annual increase of 3.5% in 1994–2015. Total nest numbers were positively correlated with estimates of spawning stocks of cod and saithe and inversely related to the subpolar gyre index (SPG‐I). During the increase in 1994–2015, average colony size at first increased and then declined. Habitat use also changed: the proportion of nests on small rocky islets (skerries) at first declined, from 69% to 44% in 1995–2003 and then increased again to about 58% in 2012–2014. Habitat changes were probably a response to changed patterns of human disturbance. Breeding density, as nests per km2 sea <20 m deep, was rather uniform among five defined regions in 1975–1996. Thereafter, densities became much higher in two sheltered regions with kelp forests and in one mostly exposed region. A second exposed region remained low and in the third nest numbers declined markedly. Thus, carrying capacity was higher in sheltered regions where cormorant breeding had historically been depressed by human disturbance. Brood size varied little among regions but declined with the years from about 2.5 to 1.8. The proportion of juveniles in September (fecundity) declined in 1998–2015 from over 0.4 to 0.3 and was inversely correlated with year and nest numbers, if outlier years were excluded, suggesting resource limitation. Survival of juvenile cormorants in September–February was estimated at 0.471 ± 0.066 SE. Commercial fish stocks and climate indices were not correlated with the ... Other/Unknown Material Iceland Data Archiving and Networked Services (DANS): EASY (KNAW - Koninklijke Nederlandse Akademie van Wetenschappen) |
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Data Archiving and Networked Services (DANS): EASY (KNAW - Koninklijke Nederlandse Akademie van Wetenschappen) |
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Life sciences medicine and health care |
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Life sciences medicine and health care Gardarsson, Arnthor Jonsson, Jon Einar Data from: Numbers and distribution of the Great Cormorant in Iceland: limitation at the regional and metapopulation level |
topic_facet |
Life sciences medicine and health care |
description |
We studied a metapopulation of great cormorant (Phalacrocorax carbo) in Iceland, using complete aerial censuses of nests in 25 years during 1975–2015. Age composition was estimated in 1998–2014 by ground surveys in September and February. Brood size was estimated from aerial photographs in 2007–2015. Weather, food, breeding habitat, and density were considered as explanatory variables when examining numerical and distributional changes in the cormorant metapopulation. In 1975–1990 total nest numbers changed little, very low numbers about 1992 were followed by an annual increase of 3.5% in 1994–2015. Total nest numbers were positively correlated with estimates of spawning stocks of cod and saithe and inversely related to the subpolar gyre index (SPG‐I). During the increase in 1994–2015, average colony size at first increased and then declined. Habitat use also changed: the proportion of nests on small rocky islets (skerries) at first declined, from 69% to 44% in 1995–2003 and then increased again to about 58% in 2012–2014. Habitat changes were probably a response to changed patterns of human disturbance. Breeding density, as nests per km2 sea <20 m deep, was rather uniform among five defined regions in 1975–1996. Thereafter, densities became much higher in two sheltered regions with kelp forests and in one mostly exposed region. A second exposed region remained low and in the third nest numbers declined markedly. Thus, carrying capacity was higher in sheltered regions where cormorant breeding had historically been depressed by human disturbance. Brood size varied little among regions but declined with the years from about 2.5 to 1.8. The proportion of juveniles in September (fecundity) declined in 1998–2015 from over 0.4 to 0.3 and was inversely correlated with year and nest numbers, if outlier years were excluded, suggesting resource limitation. Survival of juvenile cormorants in September–February was estimated at 0.471 ± 0.066 SE. Commercial fish stocks and climate indices were not correlated with the ... |
author |
Gardarsson, Arnthor Jonsson, Jon Einar |
author_facet |
Gardarsson, Arnthor Jonsson, Jon Einar |
author_sort |
Gardarsson, Arnthor |
title |
Data from: Numbers and distribution of the Great Cormorant in Iceland: limitation at the regional and metapopulation level |
title_short |
Data from: Numbers and distribution of the Great Cormorant in Iceland: limitation at the regional and metapopulation level |
title_full |
Data from: Numbers and distribution of the Great Cormorant in Iceland: limitation at the regional and metapopulation level |
title_fullStr |
Data from: Numbers and distribution of the Great Cormorant in Iceland: limitation at the regional and metapopulation level |
title_full_unstemmed |
Data from: Numbers and distribution of the Great Cormorant in Iceland: limitation at the regional and metapopulation level |
title_sort |
data from: numbers and distribution of the great cormorant in iceland: limitation at the regional and metapopulation level |
publishDate |
2019 |
url |
http://nbn-resolving.org/urn:nbn:nl:ui:13-p0-14h3 https://easy.dans.knaw.nl/ui/datasets/id/easy-dataset:125863 |
genre |
Iceland |
genre_facet |
Iceland |
op_relation |
doi:10.5061/dryad.mt5q8m2/1 doi:10.1002/ece3.5028 http://nbn-resolving.org/urn:nbn:nl:ui:13-p0-14h3 doi:10.5061/dryad.mt5q8m2 https://easy.dans.knaw.nl/ui/datasets/id/easy-dataset:125863 |
op_rights |
OPEN_ACCESS: The data are archived in Easy, they are accessible elsewhere through the DOI https://dans.knaw.nl/en/about/organisation-and-policy/legal-information/DANSLicence.pdf |
op_doi |
https://doi.org/10.5061/dryad.mt5q8m2/110.1002/ece3.502810.5061/dryad.mt5q8m2 |
_version_ |
1770272373096841216 |