Journal of Ornithology

, Volume 159, Issue 1, pp 141–150 | Cite as

Sex and breeding status affect prey composition of Harpy Eagles Harpia harpyja

  • Everton B. P. Miranda
  • Edwin Campbell-Thompson
  • Angel Muela
  • Félix Hernán Vargas
Original Article


Foraging behavior may show considerable variation among population classes—such as sex and breeding class—that can be consequence of the groups’ specific constraints and roles. In raptors, differential parental roles related to foraging have been the main explanation for males being smaller than females, as smaller males have been described to be more efficient foragers. During one phase of breeding, only males forage, requiring them to feed themselves, females and young. This is expected to induce changes in foraging behavior of breeders compared to non-breeders. By comparing prey taken by floaters and breeders of Harpy Eagles (Harpia harpyja), we describe some effects of breeding and sex on the diet. Here we show that diet traits differed between male and female floaters, and between floaters and breeders. Juvenile prey was three times more common in the diet of males than that of females. Sloths were more common prey among females than among males (53 vs. 37%). Males preyed four times more on terrestrial animals than did females, and showed a greater niche width than females (6.0 vs. 3.4). The prey of breeders was smaller than that of non-breeders (on average 3.64 vs. 4.24 kg). Non-breeders had a larger niche width than breeders. Our data provide support for the hypothesis of parental role differentiation as an explanation for reversed sexual size dimorphism in raptors.


Reversed sexual size dimorphism Breeding constraints Role differentiation hypothesis Foraging Raptor Floater 


Geschlecht und Brutstatus beeinflussen die Beutezusammensetzung von Harpyien

Das Verhalten bei der Nahrungssuche kann sich zwischen den Populationsklassen—wie beispielweise Geschlecht und Brutklasse—beträchtlich unterscheiden, welches eine Folge der spezifischen Beschränkungen und Rollen dieser Gruppen sein kann. Bei Greifvögeln gelten die unterschiedlichen Rollen der Elternvögel bei der Nahrungssuche als die hauptsächliche Erklärung dafür, dass die Männchen kleiner sind als die Weibchen, da die kleineren Männchen als die effizienteren Jäger gelten. Während eines Abschnitts des Brutgeschehens jagen nur die Männchen, welche daher nicht nur sich selbst, sondern auch noch die Weibchen und die Jungvögel mit Nahrung versorgen müssen. Dies lässt Änderungen im Jagdverhalten zwischen Brutvögeln und Nichtbrütern erwarten. Im Vergleich von Beutetieren nicht-territorialer Harpyien (Harpia harpyja) mit denen von Brutvögeln beschreiben wir einige Einflüsse von Brutstatus und Geschlecht auf die Nahrungszusammensetzung. Hier zeigen wir, dass sich die Ernährungsgewohnheiten nicht-territorialer Männchen und Weibchen sowie diejenigen der nicht-territorialen Vögel und Brutvögel unterscheiden. Im Nahrungsspektrum der Männchen waren Jungtiere dreimal häufiger vertreten als in dem der Weibchen. Faultiere wurden häufiger zur Beute von Weibchen als von Männchen (53% gegenüber 37%). Männchen erbeuteten viermal häufiger bodenlebende Tiere als die Weibchen und wiesen eine größere Nischenbreite auf als diese (6,0 gegenüber 3,4). Die Beutetiere der Brutvögel waren kleiner als die der Nichtbrüter (im Schnitt 3,64 kg gegenüber 4,24 kg). Nichtbrüter nutzten eine größere Nischenbreite als Brutvögel. Unsere Daten unterstützen die Hypothese der elterlichen Rollenverteilung als Erklärung für den umgekehrten Größendimorphismus bei Greifvögeln.



We thank the many donors who supported The Peregrine Fund’s Harpy Eagle Restoration Program: The U.S. Agency for International Development (USAID), Archie W. and Grace Berry Foundation, Burns Family Foundation, Butler Foundation, CEMEX Panama, Jim and Barbara Cimino, Liz Claiborne and Art Ortenberg Foundation, Disney Worldwide Conservation Fund, Walt Disney Company Foundation, Evie Donaldson, Charles Engelhard Foundation, ExxonMobil Foundation, Greater Los Angeles Zoo Association, Howard Gilman Foundation, Houston Zoo, Diane A. Ledder Charitable Trust, Ledder Family Charitable Trust, Mr. and Mrs. Peter Manigault, Ruth O. Mutch, Newman’s Own Organics, Norcross Wildlife Foundation, Offield Family Foundation, Paxson H. Offield, Pennzoil-Quaker State Company, Don Tyson, Wallace Genetic Foundation, Julie A. Wrigley, Wolf Creek Charitable Foundation, Zoological Society of San Diego, and other important donors. EBPM thanks Rufford Small Grants (Grant no. 18743-1), Rainforest Biodiversity Group, Idea Wild and The Explorers Club Exploration Fund–“Mamont Scholars Program” for their financial support. EBPM received logistical support from the Peugeot-ONF Carbon Sink Reforestation Project, based at the São Nicolau Farm in Cotriguaçu, Mato Grosso, Brazil. This Project is a Peugeot initiative to fulfill some of the Kyoto Protocol directions and is run by the ONF-Brasil enterprise. Victor Landeiro and Marcelo “Salsicha” Segall provided useful discussions on data analysis and theory. All research protocols and capture procedures applied for Harpy Eagles in Soberania National Park were approved by the National Environmental Authority of Panama Committee on Animal Care and were in accordance with the Guidelines of The Peregrine Fund’s Council on Animal Care. The Peregrine Fund´s Harpy Eagle Restoration Program complied with the laws of Panama during the time in which the project was carried out. We also thank staff and volunteers who have participated in The Peregrine Fund’s Harpy Eagle Restoration Program.

Supplementary material

10336_2017_1482_MOESM1_ESM.docx (1.6 mb)
Supplementary material 1 (DOCX 1622 kb)


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Copyright information

© Dt. Ornithologen-Gesellschaft e.V. 2017

Authors and Affiliations

  • Everton B. P. Miranda
    • 1
    • 2
  • Edwin Campbell-Thompson
    • 2
    • 3
  • Angel Muela
    • 2
  • Félix Hernán Vargas
    • 2
  1. 1.ONF Brasil Gestão FlorestalCotriguaçuBrazil
  2. 2.The Peregrine FundBoiseUSA
  3. 3.Fundación Águilas de Los AndesPereiraColombia

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