Applicability of external measurements to sexing of the Cape petrel Daption capense at within‐pair, within‐population and between‐population scales
Abstract Sexual size dimorphism in the Cape petrel Daption capense was analysed to improve methods for sexing live birds in field studies. Samples originated from two geographically distant study populations in the Antarctic: Nelson Island, South Shetland Islands (sample N: 83 M, 89 F), and Ardery a...
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Language: | English |
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Wiley
1998
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Online Access: | http://dx.doi.org/10.1111/j.1469-7998.1998.tb00122.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1469-7998.1998.tb00122.x https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1469-7998.1998.tb00122.x https://zslpublications.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1469-7998.1998.tb00122.x |
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crwiley:10.1111/j.1469-7998.1998.tb00122.x 2024-06-02T07:58:08+00:00 Applicability of external measurements to sexing of the Cape petrel Daption capense at within‐pair, within‐population and between‐population scales Weidinger, Karel van Franeker, Jan Andries 1998 http://dx.doi.org/10.1111/j.1469-7998.1998.tb00122.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1469-7998.1998.tb00122.x https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1469-7998.1998.tb00122.x https://zslpublications.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1469-7998.1998.tb00122.x en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Journal of Zoology volume 245, issue 4, page 473-482 ISSN 0952-8369 1469-7998 journal-article 1998 crwiley https://doi.org/10.1111/j.1469-7998.1998.tb00122.x 2024-05-03T10:36:01Z Abstract Sexual size dimorphism in the Cape petrel Daption capense was analysed to improve methods for sexing live birds in field studies. Samples originated from two geographically distant study populations in the Antarctic: Nelson Island, South Shetland Islands (sample N: 83 M, 89 F), and Ardery and O'Connor Islands, Windmill Islands (sample A: 36 M, 27 F). Using single characters with cut points calculated from sexed individuals, about 59–76% (N; best separator tarsus length) and 61–86% (A; best separator tube length) of birds could be assigned to the correct sex. Combination of characters improved performance of sample‐specific discriminant functions to a maximum of 84% in the N‐sample (five characters) and 95% in the A‐sample (four characters). The most useful character sets as well as ranking of individual characters (their weights) differed between samples. At the same time, cross‐testing revealed asymmetry in the applicability of sample‐specific functions to the other sample. Hence, the method of a generalized discriminant ( Auk 110 : 492–502, 1993) was implemented and tested to develop a species‐specific discriminant for the Cape petrel. For all examined character sets, results of their cross‐application to the other sample were improved by using character weights estimated from combined samples instead of weights derived only from the original sample. The generalized function (tube length + 1.05*bill depth at tube + 0.72*culmen length + 0.07*wing length) combined with a cut point calculated from a distribution of discriminant scores (assumed mixture of two normal distributions with possibly unequal variances) is suggested as currently the best compromise for sexing Cape petrels in populations for which specific functions are not yet available: comparison with our best sample‐specific functions shows a decrease in accuracy by only 1% to 3%. However, examination of other promising characters (head length, bill depth at gonys, mid‐toe length) is recommended to improve further a generalized discriminant. ... Article in Journal/Newspaper Antarc* Antarctic Cape Petrel Cape Petrels Daption capense Nelson Island South Shetland Islands Windmill Islands Wiley Online Library Antarctic Nelson Island ENVELOPE(-59.050,-59.050,-62.300,-62.300) O'Connor ENVELOPE(-58.383,-58.383,-62.067,-62.067) South Shetland Islands The Antarctic Windmill Islands ENVELOPE(110.417,110.417,-66.350,-66.350) Journal of Zoology 245 4 473 482 |
institution |
Open Polar |
collection |
Wiley Online Library |
op_collection_id |
crwiley |
language |
English |
description |
Abstract Sexual size dimorphism in the Cape petrel Daption capense was analysed to improve methods for sexing live birds in field studies. Samples originated from two geographically distant study populations in the Antarctic: Nelson Island, South Shetland Islands (sample N: 83 M, 89 F), and Ardery and O'Connor Islands, Windmill Islands (sample A: 36 M, 27 F). Using single characters with cut points calculated from sexed individuals, about 59–76% (N; best separator tarsus length) and 61–86% (A; best separator tube length) of birds could be assigned to the correct sex. Combination of characters improved performance of sample‐specific discriminant functions to a maximum of 84% in the N‐sample (five characters) and 95% in the A‐sample (four characters). The most useful character sets as well as ranking of individual characters (their weights) differed between samples. At the same time, cross‐testing revealed asymmetry in the applicability of sample‐specific functions to the other sample. Hence, the method of a generalized discriminant ( Auk 110 : 492–502, 1993) was implemented and tested to develop a species‐specific discriminant for the Cape petrel. For all examined character sets, results of their cross‐application to the other sample were improved by using character weights estimated from combined samples instead of weights derived only from the original sample. The generalized function (tube length + 1.05*bill depth at tube + 0.72*culmen length + 0.07*wing length) combined with a cut point calculated from a distribution of discriminant scores (assumed mixture of two normal distributions with possibly unequal variances) is suggested as currently the best compromise for sexing Cape petrels in populations for which specific functions are not yet available: comparison with our best sample‐specific functions shows a decrease in accuracy by only 1% to 3%. However, examination of other promising characters (head length, bill depth at gonys, mid‐toe length) is recommended to improve further a generalized discriminant. ... |
format |
Article in Journal/Newspaper |
author |
Weidinger, Karel van Franeker, Jan Andries |
spellingShingle |
Weidinger, Karel van Franeker, Jan Andries Applicability of external measurements to sexing of the Cape petrel Daption capense at within‐pair, within‐population and between‐population scales |
author_facet |
Weidinger, Karel van Franeker, Jan Andries |
author_sort |
Weidinger, Karel |
title |
Applicability of external measurements to sexing of the Cape petrel Daption capense at within‐pair, within‐population and between‐population scales |
title_short |
Applicability of external measurements to sexing of the Cape petrel Daption capense at within‐pair, within‐population and between‐population scales |
title_full |
Applicability of external measurements to sexing of the Cape petrel Daption capense at within‐pair, within‐population and between‐population scales |
title_fullStr |
Applicability of external measurements to sexing of the Cape petrel Daption capense at within‐pair, within‐population and between‐population scales |
title_full_unstemmed |
Applicability of external measurements to sexing of the Cape petrel Daption capense at within‐pair, within‐population and between‐population scales |
title_sort |
applicability of external measurements to sexing of the cape petrel daption capense at within‐pair, within‐population and between‐population scales |
publisher |
Wiley |
publishDate |
1998 |
url |
http://dx.doi.org/10.1111/j.1469-7998.1998.tb00122.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1469-7998.1998.tb00122.x https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1469-7998.1998.tb00122.x https://zslpublications.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1469-7998.1998.tb00122.x |
long_lat |
ENVELOPE(-59.050,-59.050,-62.300,-62.300) ENVELOPE(-58.383,-58.383,-62.067,-62.067) ENVELOPE(110.417,110.417,-66.350,-66.350) |
geographic |
Antarctic Nelson Island O'Connor South Shetland Islands The Antarctic Windmill Islands |
geographic_facet |
Antarctic Nelson Island O'Connor South Shetland Islands The Antarctic Windmill Islands |
genre |
Antarc* Antarctic Cape Petrel Cape Petrels Daption capense Nelson Island South Shetland Islands Windmill Islands |
genre_facet |
Antarc* Antarctic Cape Petrel Cape Petrels Daption capense Nelson Island South Shetland Islands Windmill Islands |
op_source |
Journal of Zoology volume 245, issue 4, page 473-482 ISSN 0952-8369 1469-7998 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1111/j.1469-7998.1998.tb00122.x |
container_title |
Journal of Zoology |
container_volume |
245 |
container_issue |
4 |
container_start_page |
473 |
op_container_end_page |
482 |
_version_ |
1800741408071483392 |