Abstract
There is a paucity of studies investigating the digestive efficiencies of avian frugivores fed fibrous (also referred to as woolly) aril pulp. We fed whole Strelitzia nicolai seeds with arils to captive Red-winged Starlings (Onychognathus morio) to determine daily food and energy intake, digestive transit time and assimilation efficiency. Strelitzia nicolai arils were found to contain a remarkably high lipid content (66.78 %), with a correspondingly low water (7.61 %) and protein (5.79 %) content. Birds generally ate only the aril of S. nicolai seeds, but if they swallowed the seeds whole then they either defecated or regurgitated the seeds without the aril. Red-winged Starlings were found to have fast digestive transit times (approx. 24 min) and very high apparent assimilation efficiencies (approx. 96 %) of the aril of S. nicolai seeds.
Zusammenfassung
Die Nahrungsverwertung von mit Samenkernen der Baumstrelitzie ( Strelitzia nicolai ) gefütterten Rotschwingenstaren ( Onychognathus morio )
Es gibt nur wenige Untersuchungen über die Nahrungsverwertung von früchtefressenden Vögeln, die mit faserigen Samenkernen gefüttert werden. Deshalb wurden in dieser Untersuchung komplette Samen von Baumstrelitzien inklusive der faserigen Kerne an gekäfigte Rotschwingenstare verfüttert, um die tägliche Aufnahme von Nahrung und Energie, die Verdauungszeit sowie die Effizienz der Nahrungsverwertung zu bestimmen. Die Kerne der Baumstrelitzie zeigen mit 66,78 % einen erstaunlich hohen Fett- und einen entsprechend niedrigen Wasser- (7,61 %) und Eiweiß-Gehalt (5,79 %). Im Allgemeinen aßen die Vögel nur die Samenkerne der Baumstrelitzien, doch wenn sie die kompletten Samen verschluckten, schieden sie diese ohne die Kerne entweder im Kot oder durch Würgen wieder aus. Die Rotschwingenstare zeigten eine nur kurze Verdauungszeit (ca. 24 Min.) und eine sehr hohe (ca. 96 %) Effizienz in ihrer Verwertung von Samenkernen der Baumstrelitzien.
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Acknowledgments
A.-L. Wilson would like to thank the University of KwaZulu-Natal and the National Research Foundation for financial assistance. We thank H. Baijnath for fruit collection; and M. Brown, the Animal House and T. Mjwara for housing and caring for the Red-winged Starlings. Ethical clearance for this study has been approved by the Animal Ethics sub-committee of the University of KwaZulu-Natal and the experiments comply with the current laws of South Africa.
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Communicated by K. C. Klasing.
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Wilson, AL., Shuttleworth, A. & Downs, C.T. Assimilation efficiency of the Red-winged Starling Onychognathus morio fed Strelitzia nicolai arils. J Ornithol 156, 323–326 (2015). https://doi.org/10.1007/s10336-014-1111-3
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DOI: https://doi.org/10.1007/s10336-014-1111-3