Survival estimates for the greater crested tern Thalasseus bergii in southern Africa |
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| Authors: | A Payo-Payo A Sanz-Aguilar D Gaglio RB Sherley TR Cook R Altwegg |
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| Institution: | 1. Group of Ecology and Animal Demography (GEDA), Mediterranean Institute for Advanced Studies (IMEDEA, CSIC-UIB), Esporles, Spain;2. Percy FitzPatrick Institute of African Ornithology, DST-NRF Centre of Excellence, University of Cape Town, Cape Town, South Africa;3. Percy FitzPatrick Institute of African Ornithology, DST-NRF Centre of Excellence, University of Cape Town, Cape Town, South Africa;4. Environment and Sustainability Institute, University of Exeter, Penryn, Cornwall, United Kingdom;5. Marine Research Institute, Department of Biological Sciences, University of Cape Town, Cape Town, South Africa;6. Institute of Ecology and Environmental Sciences, Evolutionary Ecophysiology Team, University Pierre et Marie Curie, Paris, France;7. Statistics in Ecology, Environment and Conservation, Department of Statistical Sciences, and African Climate and Development Initiative, University of Cape Town, Cape Town, South Africa |
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| Abstract: | The nominate race of the greater crested tern Thalasseus bergii breeds only along the coast of the Benguela region (west coast) of southern Africa, where its population is increasing, in contrast to other species of breeding seabirds in the region which similarly depend on forage fish. Although this population’s trends are well known, its demographic parameters remain obscure. We used multi-event capture–recapture–recovery modelling to provide the first estimates of survival. The survival rate of birds older than two years was 0.93 (0.91–0.95); second-year survival was 0.93 (0.90–0.95) and first-year survival was 0.80 (0.73–0.85). A resighting of a 34-year-old bird is a new longevity record for the species. Population growth rates projected with a Leslie matrix model that included our survival estimates were very similar to estimates from annual counts of the breeding population (7–8% y?1), suggesting that these survival estimates adequately describe the species’ demography. High survival rates have likely contributed to the species’ recent population increase in the region. |
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| Keywords: | capture–recapture method demography Leslie matrix longevity population dynamics recovery model seabirds swift tern |
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