The dispersion of red knots Calidris canutus in Africa — is southern Africa a buffer for West Africa?
The Siberian subspecies of the red knot Calidris canutus canutus spends the non-breeding season largely in West Africa (Mauritania and Guinea Bissau), where approximately half a million occurred in the 1980s. It was a rarely seen in southern Africa in the early part of the 20th century, but there we...
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ftjafricanj:oai:ojs.ajol.info:article/70490 2023-05-15T15:11:59+02:00 The dispersion of red knots Calidris canutus in Africa — is southern Africa a buffer for West Africa? Summers, RW Underhill, LG Waltner, M 2011-10-12 application/pdf http://www.ajol.info/index.php/ajms/article/view/70490 eng eng NISC http://www.ajol.info/index.php/ajms/article/view/70490/59095 http://www.ajol.info/index.php/ajms/article/view/70490 Copyright for articles published in this journal is retained by the publisher. African Journal of Marine Science; Vol 33, No 2 (2011) 1814-232X info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Peer-reviewed Article 2011 ftjafricanj 2017-03-05T06:36:29Z The Siberian subspecies of the red knot Calidris canutus canutus spends the non-breeding season largely in West Africa (Mauritania and Guinea Bissau), where approximately half a million occurred in the 1980s. It was a rarely seen in southern Africa in the early part of the 20th century, but there were about 12 500 in the 1970s and 1980s. The main sites were Langebaan Lagoon, Berg River Estuary, Olifants River Estuary (South Africa) and Walvis Bay Lagoon (Namibia). There was a decline in the number of red knots at Langebaan Lagoon in the 1990s, to around 20% of the number that occurred there in the 1980s. Numbers remained low in the 2000s. In addition, the percentage that remained during the austral winter (the breeding season in the Arctic) declined, and there was none during the period 2001–2009. This suggested that first-year birds, which largely comprise the austral winter population, were no longer travelling to southern Africa. The decline in numbers coincided with the decline in West Africa, but it was disproportionately larger in southern Africa. The observed pattern of change is consistent with a buffer effect, whereby southern Africa represents an extension to the range to less suitable habitat (requiring a 6 000 km extension to the migration) when the population size and competition is high in the main localities in West Africa. We are probably now witnessing the gradual decline in the number of adult birds who are fixed in their use of southern Africa as their non-breeding quarters.Keywords: East Atlantic Flyway, Langebaan Lagoon, population sizeAfrican Journal of Marine Science 2011, 33(2): 203–208 Article in Journal/Newspaper Arctic Calidris canutus Red Knot AJOL - African Journals Online Arctic Austral |
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AJOL - African Journals Online |
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ftjafricanj |
language |
English |
description |
The Siberian subspecies of the red knot Calidris canutus canutus spends the non-breeding season largely in West Africa (Mauritania and Guinea Bissau), where approximately half a million occurred in the 1980s. It was a rarely seen in southern Africa in the early part of the 20th century, but there were about 12 500 in the 1970s and 1980s. The main sites were Langebaan Lagoon, Berg River Estuary, Olifants River Estuary (South Africa) and Walvis Bay Lagoon (Namibia). There was a decline in the number of red knots at Langebaan Lagoon in the 1990s, to around 20% of the number that occurred there in the 1980s. Numbers remained low in the 2000s. In addition, the percentage that remained during the austral winter (the breeding season in the Arctic) declined, and there was none during the period 2001–2009. This suggested that first-year birds, which largely comprise the austral winter population, were no longer travelling to southern Africa. The decline in numbers coincided with the decline in West Africa, but it was disproportionately larger in southern Africa. The observed pattern of change is consistent with a buffer effect, whereby southern Africa represents an extension to the range to less suitable habitat (requiring a 6 000 km extension to the migration) when the population size and competition is high in the main localities in West Africa. We are probably now witnessing the gradual decline in the number of adult birds who are fixed in their use of southern Africa as their non-breeding quarters.Keywords: East Atlantic Flyway, Langebaan Lagoon, population sizeAfrican Journal of Marine Science 2011, 33(2): 203–208 |
format |
Article in Journal/Newspaper |
author |
Summers, RW Underhill, LG Waltner, M |
spellingShingle |
Summers, RW Underhill, LG Waltner, M The dispersion of red knots Calidris canutus in Africa — is southern Africa a buffer for West Africa? |
author_facet |
Summers, RW Underhill, LG Waltner, M |
author_sort |
Summers, RW |
title |
The dispersion of red knots Calidris canutus in Africa — is southern Africa a buffer for West Africa? |
title_short |
The dispersion of red knots Calidris canutus in Africa — is southern Africa a buffer for West Africa? |
title_full |
The dispersion of red knots Calidris canutus in Africa — is southern Africa a buffer for West Africa? |
title_fullStr |
The dispersion of red knots Calidris canutus in Africa — is southern Africa a buffer for West Africa? |
title_full_unstemmed |
The dispersion of red knots Calidris canutus in Africa — is southern Africa a buffer for West Africa? |
title_sort |
dispersion of red knots calidris canutus in africa — is southern africa a buffer for west africa? |
publisher |
NISC |
publishDate |
2011 |
url |
http://www.ajol.info/index.php/ajms/article/view/70490 |
geographic |
Arctic Austral |
geographic_facet |
Arctic Austral |
genre |
Arctic Calidris canutus Red Knot |
genre_facet |
Arctic Calidris canutus Red Knot |
op_source |
African Journal of Marine Science; Vol 33, No 2 (2011) 1814-232X |
op_relation |
http://www.ajol.info/index.php/ajms/article/view/70490/59095 http://www.ajol.info/index.php/ajms/article/view/70490 |
op_rights |
Copyright for articles published in this journal is retained by the publisher. |
_version_ |
1766342748895444992 |