Brood reduction in the Blue‐eyed Shag Phalacrocorax atriceps
Brood reduction is common in a population of Blue‐eyed Shags on Signy Island, South Orkney Islands. This paper describes possible adaptations which may reduce the brood. In clutches of three, the last egg was smaller, and hatched 2.4 days later than its siblings. Whilst 78–84% of first and second (‘...
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crwiley:10.1111/j.1474-919x.1985.tb04843.x 2024-06-02T08:04:28+00:00 Brood reduction in the Blue‐eyed Shag Phalacrocorax atriceps SHAW, P. 1985 http://dx.doi.org/10.1111/j.1474-919x.1985.tb04843.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1474-919X.1985.tb04843.x https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1474-919X.1985.tb04843.x en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Ibis volume 127, issue 4, page 476-494 ISSN 0019-1019 1474-919X journal-article 1985 crwiley https://doi.org/10.1111/j.1474-919x.1985.tb04843.x 2024-05-03T10:47:39Z Brood reduction is common in a population of Blue‐eyed Shags on Signy Island, South Orkney Islands. This paper describes possible adaptations which may reduce the brood. In clutches of three, the last egg was smaller, and hatched 2.4 days later than its siblings. Whilst 78–84% of first and second (‘A’ & ‘B’) chicks fledged, only 11 % of ‘C’ chicks did. In a sample of artificially synchronized broods chick survival was as high as in normal asynchronously hatching broods, but there were more cases of total brood loss. The age at which the C chick died was related inversely to the length of the A‐C hatching interval. Relative differences in sibling weights were highest during the first 12 days, when most of the C chick deaths occurred. At this age the daily food requirements of each brood of three was one‐tenth that of each brood of two just prior to fledging. It is suggested that C chicks were unable to compete effectively for a food supply which was limited by the parents, rather than by the environment. The asymptotic weight attained by A chicks was inversely related to brood size, and was greater than that of B or C chicks. Normal asynchronous broods produced at least one heavy (A) chick and one medium weight (B) chick, whilst in synchronized broods the asymptotic weight attained was similar to that of B chicks in normal broods. Article in Journal/Newspaper Blue Eyed Shag Phalacrocorax atriceps Signy Island South Orkney Islands Wiley Online Library Signy Island ENVELOPE(-45.595,-45.595,-60.708,-60.708) South Orkney Islands ENVELOPE(-45.500,-45.500,-60.583,-60.583) Ibis 127 4 476 494 |
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English |
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Brood reduction is common in a population of Blue‐eyed Shags on Signy Island, South Orkney Islands. This paper describes possible adaptations which may reduce the brood. In clutches of three, the last egg was smaller, and hatched 2.4 days later than its siblings. Whilst 78–84% of first and second (‘A’ & ‘B’) chicks fledged, only 11 % of ‘C’ chicks did. In a sample of artificially synchronized broods chick survival was as high as in normal asynchronously hatching broods, but there were more cases of total brood loss. The age at which the C chick died was related inversely to the length of the A‐C hatching interval. Relative differences in sibling weights were highest during the first 12 days, when most of the C chick deaths occurred. At this age the daily food requirements of each brood of three was one‐tenth that of each brood of two just prior to fledging. It is suggested that C chicks were unable to compete effectively for a food supply which was limited by the parents, rather than by the environment. The asymptotic weight attained by A chicks was inversely related to brood size, and was greater than that of B or C chicks. Normal asynchronous broods produced at least one heavy (A) chick and one medium weight (B) chick, whilst in synchronized broods the asymptotic weight attained was similar to that of B chicks in normal broods. |
format |
Article in Journal/Newspaper |
author |
SHAW, P. |
spellingShingle |
SHAW, P. Brood reduction in the Blue‐eyed Shag Phalacrocorax atriceps |
author_facet |
SHAW, P. |
author_sort |
SHAW, P. |
title |
Brood reduction in the Blue‐eyed Shag Phalacrocorax atriceps |
title_short |
Brood reduction in the Blue‐eyed Shag Phalacrocorax atriceps |
title_full |
Brood reduction in the Blue‐eyed Shag Phalacrocorax atriceps |
title_fullStr |
Brood reduction in the Blue‐eyed Shag Phalacrocorax atriceps |
title_full_unstemmed |
Brood reduction in the Blue‐eyed Shag Phalacrocorax atriceps |
title_sort |
brood reduction in the blue‐eyed shag phalacrocorax atriceps |
publisher |
Wiley |
publishDate |
1985 |
url |
http://dx.doi.org/10.1111/j.1474-919x.1985.tb04843.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1474-919X.1985.tb04843.x https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1474-919X.1985.tb04843.x |
long_lat |
ENVELOPE(-45.595,-45.595,-60.708,-60.708) ENVELOPE(-45.500,-45.500,-60.583,-60.583) |
geographic |
Signy Island South Orkney Islands |
geographic_facet |
Signy Island South Orkney Islands |
genre |
Blue Eyed Shag Phalacrocorax atriceps Signy Island South Orkney Islands |
genre_facet |
Blue Eyed Shag Phalacrocorax atriceps Signy Island South Orkney Islands |
op_source |
Ibis volume 127, issue 4, page 476-494 ISSN 0019-1019 1474-919X |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1111/j.1474-919x.1985.tb04843.x |
container_title |
Ibis |
container_volume |
127 |
container_issue |
4 |
container_start_page |
476 |
op_container_end_page |
494 |
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1800749090533801984 |