Analyzing Pellets and Feces of African Royal Terns (Thalasseus maximus albididorsalis) Results in Different Estimates of Diet Composition
A frequently used method to estimate diet composition is based on the identification of fish otoliths present in pellets and feces. However, whether pellets and feces provide similar unbiased estimates of the diet remains poorly understood. The diet of African Royal Terns (Thalasseus maximus albididorsalis) breeding in the Parc National du Delta du Saloum, Senegal, was studied. Prey species composition based on otoliths in freshly regurgitated pellets and a mixture of pellets and feces (excrement) accumulated near nests during the incubation period were compared. Altogether, 59 fish species were identified. Pellets contained far less prey species than excrement. Maximum diet overlap between excrement and pellets varied between 0.34 and 0.43 (mean = 0.36). Differences between minimum and maximum overlap between both sample types were small in all years. Pellets contained almost exclusively large otoliths (widths 3.0-8.5 mm), whereas excrement contained two fractions: large sized ones, identical to those present in the pellets and smaller-sized ones (0.5-3.0 mm) originating from feces. It is hypothesized that large otoliths cannot pass the intestinal tracts of the birds and are therefore regurgitated. Differences in prey species composition in pellets and excrement could potentially be explained by a combination of seasonal changes in availability of prey species and size of otoliths. Neither pellets nor feces alone give an unbiased picture of the diet of African Royal Terns.
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Format: | Article/Letter to editor biblioteca |
Language: | English |
Subjects: | African Royal Terns, Delta du Saloum, Senegal, Thalasseus maximus albididorsalis., diet overlap, fish, otoliths, prey, |
Online Access: | https://research.wur.nl/en/publications/analyzing-pellets-and-feces-of-african-royal-terns-thalasseus-max |
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dig-wur-nl-wurpubs-5421592024-08-16 Veen, Jan Dallmeijer, Hanneke van Damme, Cindy J.G. Leopold, Mardik F. Veen, Thor Article/Letter to editor Waterbirds 41 (2018) 3 ISSN: 1524-4695 Analyzing Pellets and Feces of African Royal Terns (Thalasseus maximus albididorsalis) Results in Different Estimates of Diet Composition 2018 A frequently used method to estimate diet composition is based on the identification of fish otoliths present in pellets and feces. However, whether pellets and feces provide similar unbiased estimates of the diet remains poorly understood. The diet of African Royal Terns (Thalasseus maximus albididorsalis) breeding in the Parc National du Delta du Saloum, Senegal, was studied. Prey species composition based on otoliths in freshly regurgitated pellets and a mixture of pellets and feces (excrement) accumulated near nests during the incubation period were compared. Altogether, 59 fish species were identified. Pellets contained far less prey species than excrement. Maximum diet overlap between excrement and pellets varied between 0.34 and 0.43 (mean = 0.36). Differences between minimum and maximum overlap between both sample types were small in all years. Pellets contained almost exclusively large otoliths (widths 3.0-8.5 mm), whereas excrement contained two fractions: large sized ones, identical to those present in the pellets and smaller-sized ones (0.5-3.0 mm) originating from feces. It is hypothesized that large otoliths cannot pass the intestinal tracts of the birds and are therefore regurgitated. Differences in prey species composition in pellets and excrement could potentially be explained by a combination of seasonal changes in availability of prey species and size of otoliths. Neither pellets nor feces alone give an unbiased picture of the diet of African Royal Terns. en application/pdf https://research.wur.nl/en/publications/analyzing-pellets-and-feces-of-african-royal-terns-thalasseus-max 10.1675/063.041.0309 https://edepot.wur.nl/462558 African Royal Terns Delta du Saloum Senegal Thalasseus maximus albididorsalis. diet overlap fish otoliths prey (c) publisher Wageningen University & Research |
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African Royal Terns Delta du Saloum Senegal Thalasseus maximus albididorsalis. diet overlap fish otoliths prey African Royal Terns Delta du Saloum Senegal Thalasseus maximus albididorsalis. diet overlap fish otoliths prey |
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African Royal Terns Delta du Saloum Senegal Thalasseus maximus albididorsalis. diet overlap fish otoliths prey African Royal Terns Delta du Saloum Senegal Thalasseus maximus albididorsalis. diet overlap fish otoliths prey Veen, Jan Dallmeijer, Hanneke van Damme, Cindy J.G. Leopold, Mardik F. Veen, Thor Analyzing Pellets and Feces of African Royal Terns (Thalasseus maximus albididorsalis) Results in Different Estimates of Diet Composition |
description |
A frequently used method to estimate diet composition is based on the identification of fish otoliths present in pellets and feces. However, whether pellets and feces provide similar unbiased estimates of the diet remains poorly understood. The diet of African Royal Terns (Thalasseus maximus albididorsalis) breeding in the Parc National du Delta du Saloum, Senegal, was studied. Prey species composition based on otoliths in freshly regurgitated pellets and a mixture of pellets and feces (excrement) accumulated near nests during the incubation period were compared. Altogether, 59 fish species were identified. Pellets contained far less prey species than excrement. Maximum diet overlap between excrement and pellets varied between 0.34 and 0.43 (mean = 0.36). Differences between minimum and maximum overlap between both sample types were small in all years. Pellets contained almost exclusively large otoliths (widths 3.0-8.5 mm), whereas excrement contained two fractions: large sized ones, identical to those present in the pellets and smaller-sized ones (0.5-3.0 mm) originating from feces. It is hypothesized that large otoliths cannot pass the intestinal tracts of the birds and are therefore regurgitated. Differences in prey species composition in pellets and excrement could potentially be explained by a combination of seasonal changes in availability of prey species and size of otoliths. Neither pellets nor feces alone give an unbiased picture of the diet of African Royal Terns. |
format |
Article/Letter to editor |
topic_facet |
African Royal Terns Delta du Saloum Senegal Thalasseus maximus albididorsalis. diet overlap fish otoliths prey |
author |
Veen, Jan Dallmeijer, Hanneke van Damme, Cindy J.G. Leopold, Mardik F. Veen, Thor |
author_facet |
Veen, Jan Dallmeijer, Hanneke van Damme, Cindy J.G. Leopold, Mardik F. Veen, Thor |
author_sort |
Veen, Jan |
title |
Analyzing Pellets and Feces of African Royal Terns (Thalasseus maximus albididorsalis) Results in Different Estimates of Diet Composition |
title_short |
Analyzing Pellets and Feces of African Royal Terns (Thalasseus maximus albididorsalis) Results in Different Estimates of Diet Composition |
title_full |
Analyzing Pellets and Feces of African Royal Terns (Thalasseus maximus albididorsalis) Results in Different Estimates of Diet Composition |
title_fullStr |
Analyzing Pellets and Feces of African Royal Terns (Thalasseus maximus albididorsalis) Results in Different Estimates of Diet Composition |
title_full_unstemmed |
Analyzing Pellets and Feces of African Royal Terns (Thalasseus maximus albididorsalis) Results in Different Estimates of Diet Composition |
title_sort |
analyzing pellets and feces of african royal terns (thalasseus maximus albididorsalis) results in different estimates of diet composition |
url |
https://research.wur.nl/en/publications/analyzing-pellets-and-feces-of-african-royal-terns-thalasseus-max |
work_keys_str_mv |
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