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1995, Journal of Raptor Research
Journal of Raptor Research
Prey of the Harris’s Hawk (Parabuteo unicinctus) in a suburban area of southern Chile2006 •
In group-living carnivores, cooperative hunting may be a cause or a consequence of cooperative breeding. Harris’s Hawk (Parabuteo unicinctus), a raptor that hunts and nests in cooperative groups of 3 to 7 hawks (Mader 1975a, b; Bednarz 1987; Dawson and Mannan 1989), provides an opportunity to examine benefits and possible causes of sociality because its cooperation is facultative and the species is relatively well studied. Attempts to demonstrate factors that promoted the evolution of cooperative breeding in Harris’s Hawks have mostly been unsuccessful. For example, the reproductive performance of groups did not differ from that of pairs (Mader 1975b, Bednarz 1987). And, for the most part, researchers did not find differences in the habitat quality or the resources available in territories occupied by groups versus pairs (Bednarz and Ligon 1988, Dawson and Mannan 1991b). How- ever, Bednarz (1988) demonstrated net energetic benefits for hunting parties of 5 or 6 hawks and proposed that cooperative hunting led to social living in Harris’s Hawk. Here, we support and extend this argument with a reinterpretation of data from the published literature, including an overlooked finding of significance. We hypothesize that one benefit of cooperative hunting is to increase success in habitats that make the prey difficult to catch (e.g., a high density of hiding places). We think that this benefit could be as important as capturing and overwhelming large prey, a benefit proposed by Bednarz (1988). We propose the “challenging habitats hypothesis” (CHH), similar to an idea proposed by Dawson (1988), as an additional or alternative explanation for the maintenance and, possibly, the evolution of cooperative hunting in Harris’s Hawk. As falconers, we developed this hypothesis after many years of hunting with single and cooperative groups of 2 to 8 Harris’s Hawks in a variety of habitats. We hope to rekindle scientific inquiry into cooperation in this species.
Knowledge about activity patterns of raptors in different habitats is important to understanding their behavioral flexibility and adaptive ability. During nine months, we surveyed the activities of Harris's Hawks (Parabuteo unicinctus) for a total of 199 hours over 22 observation days in a coastal forested area of central Chi-le. The time spent in a particular activity was measured using the focal-animal sampling method. Perching was the prevalent activity within each season and day. Harris's Hawks perched more often during winter and autumn (83−95% of total time hawks were observed, N = 11,940 min), and flew more often during spring and summer (21.6−33.6% of total time hawks were observed). Except in winter, perching activity exhibited a daily, bimodal pattern. Harris's Hawks perched more often during mid-morning (09:00−11:00 h) and midday (12:00−14:00 h) in winter, during mid-morning and mid-afternoon (16:00−17:00 h) in spring and autumn, and during mid-morning and late-afternoon (19:00−21:00 h) in summer. Six flight modes were identified: gliding, cruising, soaring, hovering, diving and parachuting. Soaring was the most frequent flight mode throughout the year (46−87% of total flying time, N = 628.5 min). Within each season, time budgets for soaring differed markedly throughout the day. The Harris's Hawk's prevalent tendency to perch could be explained by its stereotyped sit-and-wait foraging mode. Perching behavior could also have conferred the advantage of access to the interior of forest remnants, allowing better exploitation of such prey patches. The prevalent use of soaring could be explained because it confers multiples advantages such as exploration, better detection of prey or intruders, territorial displays or courtship, and thermoregulation. Temporal variations in flight activities of Harris's Hawks in our study site were consistent with concurrent climate and ecological conditions. The prevalent use of perching and the diversified flight modes of Harris's Hawks probably confer a greater adaptive ability in forested areas. RESUMEN.-Conocer los patrones de actividad de las aves rapaces en hábitats distintos es importante para com-prender su flexibilidad conductual y capacidad adaptativa. Durante nueve meses monitoreamos la actividad de un grupo de peucos (Parabuteo unicinctus) por un tiempo total de 199 horas dentro de 22 días de observación en un área boscosa de Chile central. El tiempo consumido en una actividad particular fue medido usando el método de muestreo del animal focal. El perchado fue la actividad prevalente dentro de cada estación climática y del día. Los peucos percharon más a menudo durante el otoño y el invierno (83−95% del tiempo total de avistamiento, N = 11.940 min), y volaron más a menudo durante primavera y verano (22−34% del tiempo total de avistamien
2003 •
Ornitología Neotropical
Possible social foraging behavior in the Red-backed Hawk (Buteo polyosoma)2005 •
Journal of Raptor Research
Interactions Between a Group of Golden Eagles and a Herd of North American Elk2013 •
COMPORTAMIENTO REPRODUCTIVO DE UNA PAREJA DE BUTEO VENTRALIS EN EL SUR DE CHILE
Breeding behavior of a pair Rufous-tailed Hawk (Buteo ventralis) in the southern Chile. Journal of Raptor Research2012 •
Buteo ventralis es una rapaz endémica y virtualmente desconocida de los bosques templados de Nothofagus de Chile y Argentina. Estudiamos el comportamiento reproductivo de una pareja en el mismo nido durante dos temporadas reproductivas consecutivas (2008-09 y 2009-2010) en el Monumento Natural Cerro Ñielol, cerca de Temuco en el sur de Chile, de julio del 2008 a marzo del 2010. La pareja construyó y mejoró un nido en un árbol alto de Aextoxicon punctatum en el fondo de una quebrada densamente vegetada. El macho defendió activamente el territorio. La hembra incubó exclusivamente los huevos durante 33-34 días, comenzando a principios de octubre. La pareja produjo tres y un pichones, en 2008-09 y 2009-2010 respectivamente, los cuales dejaron el nido a los 49 - 56 días de edad y dejaron de visitar el nido a los 91 días de edad. La pareja y los juveniles permanecieron en el área del nido hasta finales de marzo. El comportamiento reproductivo de B. ventralis fue similar al de otros Buteo, especialmente al de su pariente más cercano, B. jamaicensis en América del Norte.
Biological Conservation
The state of the art in raptor electrocution research: A global review2007 •
Journal of Raptor Research
Potential Factors Influencing Nest Defense in Diurnal North American Raptors2006 •
Studies in Avian …
Resource selection function models as tools for regional conservation planning for Northern Goshawk in Utah2006 •
Nuestras Aves
DIETA DEL GAVILÁN MIXTO (Parabuteo u. unicinctus) EN UN HUMEDAL DE LA CIUDAD DE BUENOS AIRES2015 •
State of North …
Conservation status of North America's birds of prey2004 •
Journal of Parasitology
Parasite Infections in Nestling Red-Shouldered Hawks (Buteo lineatus) in Northeast Wisconsin2010 •
The Southwestern Naturalist
Prey of the Harris’ Hawk (Parabuteo unicinctus) during fall and winter in a coastal area of central ChileThe Southwestern Naturalist
Raptor Predation on Ord's Kangaroo Rats: Evidence for Diurnal Activity by a Nocturnal Rodent2007 •
Journal of Raptor Research
Perch use and hunting behavior of Red-tailed Hawks2004 •
2009 •
Journal of Raptor Research 35 (2): 15 1-158.
The conservation status of raptors in the Metropolitan Region, Chile.2001 •
The Wilson Journal of Ornithology
Incidence of Cartwheeling Flights in Raptors of South-Central Chile2015 •
The Wilson Journal of Ornithology
Prey Use and Provisioning Rates of Breeding Ferruginous and Swainson's Hawks on the Southern Great Plains, Usa2007 •
2006 •
1989 •
Journal of Raptor Research
Restoring Aplomado Falcons to the United StatesThe Wilson Journal of Ornithology
Home Range, Habitat Use, and Nest Site Characteristics of Mississippi Kites in the White River National Wildlife Refuge, Arkansas2010 •
2008 •
Journal of Raptor Research
Prey Use by Swainson's Hawks in the Lesser Prairie-Chicken Range of the Southern High Plains of Texas2010 •
The Journal of Wildlife Management
Estimating raptor electrocution mortality on distribution power lines in Alberta, Canada2013 •
Wilson Bulletin
A description of nests and behavior of the Gray-headed Kite1997 •
Revista Brasileira de Ornitologia
Forest-specialist raptors of the temperate forests of southern South America: a review2006 •
2000 •
Journal of Raptor Research
Seasonal variation in the diet of the White-tailed Kite (Elanus leucurus) in a suburban area of southern Chile2009 •
Journal of Raptor Research
Avian Electrocutions in Western Rajasthan, India2013 •