Quantifying bird diversity at three sites of differing herbivore presence
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ORIGINAL ARTICLE
Quantifying bird diversity at three sites of differing herbivore presence Roxane J. Francis1 · Kate J. Brandis1 · Richard T. Kingsford1 · Corey T. Callaghan1 Received: 7 April 2020 / Revised: 14 June 2020 / Accepted: 13 July 2020 © Deutsche Ornithologen-Gesellschaft e.V. 2020
Abstract Large herbivores directly and indirectly influence ecosystem function, positively and negatively affecting diversity of plants and animals, including birds. Such cascading effects are clearly important, particularly given ongoing global declines in large herbivores and many avian communities. We examined relationships between bird diversity (species richness and ShannonWeiner Index, at a species and functional group level) at three similarly vegetated and flooded sites in northern Botswana. We explored the role that herbivore presence plays in ecosystem functioning considering bird species richness was significantly higher at the site of intermediate presence, followed by the high presence site. At a functional group level, the site of highest presence consistently had the greatest functional group richness. Also, at a functional group level we identified higher species richness and diversity in the two sites where herbivores were present at high levels. This was particularly pronounced for the avian aquatic carnivore, terrestrial herbivore, and aerial invertivore functional groupings. Large herbivores probably increased habitat complexity through their browsing and grazing, altering habitat structure, alongside other benefits such as faeces deposition and mutualistic relationships, creating more niches for avian communities. Fencing out large herbivores to reduce their grazing and browsing may therefore reduce bird diversity, and correspondingly, allowing large herbivores to increase in abundance through protected areas may indirectly increase bird diversity, acknowledging over abundance may be detrimental. Keywords Africa · Avian · Management · Protected area · Biodiversity · Species loss · Elephant · Chobe · Botswana · Disturbance Zusammenfassung Quantifizierung von Vogelarten an drei Standorten mit unterschiedlicher Pflanzenfresser-Präsenz Große Pflanzenfresser beeinflussen die Funktion von Ökosystemen direkt und indirekt durch ihre positiven und negativen Auswirkungen auf die vorkommenden Pflanzen und Tiere. Solche Kaskadeneffekte sind ohne Frage wichtig, besonders in Hinblick auf den derzeitigen globalen Rückgang der großen Pflanzenfresser und vieler Vogelpopulationen. Wir untersuchten den Zusammenhang zwischen Vogelvielfalt (Artenreichtum und Shannon-Weiner-Index auf Art-Ebene und der Ebene funktionaler Gruppen) an drei ähnlich bewachsenen und überfluteten Standorten im Norden Botswanas. Wir betrachteten die Rolle der Präsenz von Pflanzenfressern für das Funktionieren des Ökosystems, wobei der Artenreichtum der Vögel an Stellen mit mittlerer Pflanzenfresser-Präsenz signifikant höher war, gefolgt von Stellen mit hoher Präsenz. Auf der Ebene funktionaler Gruppen zeigte der Standort mit höchster Präsenz den g
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