Short Note: A method for sexing the chicks of Antarctic shags
Several studies have been carried out during the last fifteen years on reproduction, population dynamics and diet of the Antarctic shag, Phalacrocorax bransfieldensis Murphy, at different localities in the South Shetland Islands (reviewed in Casaux & Barrera-Oro 2006). In both the colonies studi...
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ftconicet:oai:ri.conicet.gov.ar:11336/100299 2023-10-09T21:47:05+02:00 Short Note: A method for sexing the chicks of Antarctic shags Casaux, Ricardo Jorge Ramón, A. Baroni, A. application/pdf http://hdl.handle.net/11336/100299 eng eng Cambridge University Press info:eu-repo/semantics/altIdentifier/doi/10.1017/S0954102007000818 info:eu-repo/semantics/altIdentifier/url/https://www.cambridge.org/core/journals/antarctic-science/article/short-note-a-method-for-sexing-the-chicks-of-antarctic-shags/8080F47C3A205A90483386696498A17D http://hdl.handle.net/11336/100299 Casaux, Ricardo Jorge; Ramón, A.; Baroni, A.; Short Note: A method for sexing the chicks of Antarctic shags; Cambridge University Press; Antarctic Science; 20; 2; 4-2008; 147-148 0954-1020 CONICET Digital CONICET info:eu-repo/semantics/openAccess https://creativecommons.org/licenses/by-nc-sa/2.5/ar/ Antarctic Shag sex determination Antacrctica https://purl.org/becyt/ford/1.6 https://purl.org/becyt/ford/1 info:eu-repo/semantics/article info:ar-repo/semantics/artículo info:eu-repo/semantics/publishedVersion ftconicet https://doi.org/10.1017/S0954102007000818 2023-09-24T19:58:15Z Several studies have been carried out during the last fifteen years on reproduction, population dynamics and diet of the Antarctic shag, Phalacrocorax bransfieldensis Murphy, at different localities in the South Shetland Islands (reviewed in Casaux & Barrera-Oro 2006). In both the colonies studied and in other colonies counted we observed that the number of breeding pairs was steadily decreasing (Casaux & Barrera-Oro 2006). Casaux & Baroni (2002) had earlier suggested that such a decreasing trend might be related, at least partially, to a marked decrease in the inshore populations of two fish prey species, the marbled notothen Notothenia rossii Richardson and the humphead notothen Gobionotothen gibberifrons Lönnberg (Barrera-Oro et al. 2000), which had been studied over a period of 19 years in coastal waters of the South Shetland Islands. Exactly how a reduction in prey availability affects the shag populations (e.g. migration of breeders to other colonies in the area or to new breeding areas, a decrease in the rate of recruitment, an increase in adult mortality, variation in the age at first breeding, etc) is not clear. To investigate this, we started a banding programme at Nelson Island, South Shetland Islands. We postulated that the processes might operate with different intensities on individuals of different sexes, so all individuals in each population studied needed to be sexed. This posed problems for chicks which have monomorphic plumage and no differences in vocalisations (Casaux & Baroni 2000), so that the normal methods for sexing in the field would not work. As most of the external morphological characters in the chicks of Antarctic shags have stabilized by 45–50 days old (Casaux 1998), Casaux & Baroni (2000) had suggested that the use of discriminant functions originally developed for adults could be an appropriate method to sex chicks more than 50 days old. Fil: Casaux, Ricardo Jorge. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del ... Article in Journal/Newspaper Antarc* Antarctic Antarctic Science Nelson Island Notothenia rossii South Shetland Islands CONICET Digital (Consejo Nacional de Investigaciones Científicas y Técnicas) Antarctic The Antarctic South Shetland Islands Ricardo ENVELOPE(-63.033,-63.033,-64.867,-64.867) Nelson Island ENVELOPE(-59.050,-59.050,-62.300,-62.300) Antarctic Science 20 2 147 148 |
institution |
Open Polar |
collection |
CONICET Digital (Consejo Nacional de Investigaciones Científicas y Técnicas) |
op_collection_id |
ftconicet |
language |
English |
topic |
Antarctic Shag sex determination Antacrctica https://purl.org/becyt/ford/1.6 https://purl.org/becyt/ford/1 |
spellingShingle |
Antarctic Shag sex determination Antacrctica https://purl.org/becyt/ford/1.6 https://purl.org/becyt/ford/1 Casaux, Ricardo Jorge Ramón, A. Baroni, A. Short Note: A method for sexing the chicks of Antarctic shags |
topic_facet |
Antarctic Shag sex determination Antacrctica https://purl.org/becyt/ford/1.6 https://purl.org/becyt/ford/1 |
description |
Several studies have been carried out during the last fifteen years on reproduction, population dynamics and diet of the Antarctic shag, Phalacrocorax bransfieldensis Murphy, at different localities in the South Shetland Islands (reviewed in Casaux & Barrera-Oro 2006). In both the colonies studied and in other colonies counted we observed that the number of breeding pairs was steadily decreasing (Casaux & Barrera-Oro 2006). Casaux & Baroni (2002) had earlier suggested that such a decreasing trend might be related, at least partially, to a marked decrease in the inshore populations of two fish prey species, the marbled notothen Notothenia rossii Richardson and the humphead notothen Gobionotothen gibberifrons Lönnberg (Barrera-Oro et al. 2000), which had been studied over a period of 19 years in coastal waters of the South Shetland Islands. Exactly how a reduction in prey availability affects the shag populations (e.g. migration of breeders to other colonies in the area or to new breeding areas, a decrease in the rate of recruitment, an increase in adult mortality, variation in the age at first breeding, etc) is not clear. To investigate this, we started a banding programme at Nelson Island, South Shetland Islands. We postulated that the processes might operate with different intensities on individuals of different sexes, so all individuals in each population studied needed to be sexed. This posed problems for chicks which have monomorphic plumage and no differences in vocalisations (Casaux & Baroni 2000), so that the normal methods for sexing in the field would not work. As most of the external morphological characters in the chicks of Antarctic shags have stabilized by 45–50 days old (Casaux 1998), Casaux & Baroni (2000) had suggested that the use of discriminant functions originally developed for adults could be an appropriate method to sex chicks more than 50 days old. Fil: Casaux, Ricardo Jorge. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del ... |
format |
Article in Journal/Newspaper |
author |
Casaux, Ricardo Jorge Ramón, A. Baroni, A. |
author_facet |
Casaux, Ricardo Jorge Ramón, A. Baroni, A. |
author_sort |
Casaux, Ricardo Jorge |
title |
Short Note: A method for sexing the chicks of Antarctic shags |
title_short |
Short Note: A method for sexing the chicks of Antarctic shags |
title_full |
Short Note: A method for sexing the chicks of Antarctic shags |
title_fullStr |
Short Note: A method for sexing the chicks of Antarctic shags |
title_full_unstemmed |
Short Note: A method for sexing the chicks of Antarctic shags |
title_sort |
short note: a method for sexing the chicks of antarctic shags |
publisher |
Cambridge University Press |
url |
http://hdl.handle.net/11336/100299 |
long_lat |
ENVELOPE(-63.033,-63.033,-64.867,-64.867) ENVELOPE(-59.050,-59.050,-62.300,-62.300) |
geographic |
Antarctic The Antarctic South Shetland Islands Ricardo Nelson Island |
geographic_facet |
Antarctic The Antarctic South Shetland Islands Ricardo Nelson Island |
genre |
Antarc* Antarctic Antarctic Science Nelson Island Notothenia rossii South Shetland Islands |
genre_facet |
Antarc* Antarctic Antarctic Science Nelson Island Notothenia rossii South Shetland Islands |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1017/S0954102007000818 info:eu-repo/semantics/altIdentifier/url/https://www.cambridge.org/core/journals/antarctic-science/article/short-note-a-method-for-sexing-the-chicks-of-antarctic-shags/8080F47C3A205A90483386696498A17D http://hdl.handle.net/11336/100299 Casaux, Ricardo Jorge; Ramón, A.; Baroni, A.; Short Note: A method for sexing the chicks of Antarctic shags; Cambridge University Press; Antarctic Science; 20; 2; 4-2008; 147-148 0954-1020 CONICET Digital CONICET |
op_rights |
info:eu-repo/semantics/openAccess https://creativecommons.org/licenses/by-nc-sa/2.5/ar/ |
op_doi |
https://doi.org/10.1017/S0954102007000818 |
container_title |
Antarctic Science |
container_volume |
20 |
container_issue |
2 |
container_start_page |
147 |
op_container_end_page |
148 |
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1779309831321026560 |