Spizaetus hawk-eagles as predators of arboreal colobines

Abstract

The predation pressure put on primates by diurnal birds of prey differs greatly between continents. Africa and South America have specialist raptors (e.g. crowned hawk-eagle Stephanoaetus coronatus and harpy eagle Harpia harpyja) whereas in Asia the only such specialist's (Philippine eagle Pithecophaga jefferyi) distribution is largely allopatric with primates. The almost universal absence of polyspecific groups in Asia (common in Africa and South America) may indicate reduced predation pressure. As such there is almost no information on predation pressures on primates in Asia by raptors. Here we report successful predation of a juvenile banded langur Presbytis femoralis (~2 kg) by a changeable hawk-eagle Spizaetus cirrhatus. The troop that was attacked displayed no signs of being alarmed, and no calls were made before the event. We argue that in insular Southeast Asia, especially, large Spizaetus hawk-eagles (~2 kg) are significant predators of arboreal colobines. Using data on the relative size of sympatric Spizaetus hawk-eagles and colobines we make predictions on where geographically we can expect the highest predation pressure (Thai-Malay Peninsula) and which colobines are least (Nasalis larvatus, Trachypithecus auratus, P. thomasi) and most (P. femoralis, T. cristatus) affected.

Sleeping site selection and presleep behavior in wild pigtailed macaques

“…The predator's reaction to the observer's approach made it conspicuous and induced alarm calls by the macaques. The terrestrial Asian golden cat (Felis temminckii) and birds of prey, such as the mountain hawk eagle (Spizaetus nipalensis) and crested serpent eagles (Spilornis cheela), are less likely to represent a threat [Fam & Nijman, 2011]; birds of prey pose a threat mainly during the day.…”

Group Composition and Monandry in Grizzled Langurs, Presbytis comata, on Java

“…It is suggested that polyspecific associations are formed under predation pressure [e.g., Struhsaker, 1981Struhsaker, , 2000Noë and Bshary, 1997]. Differences between Africa and the Neotropics on the one hand and Asia on the other have most commonly been explained by differences in predation pressure, in particular the apparent absence of specialized primate-targeting raptors in Asia [Hart, 2007;Fam and Nijman, 2011].…”

“…comata infrequently forms polyspecific associations with other langurs and gibbons. Polyspecific associations between Presbytis and other langurs ( Presbytis , Trachypithecus , Nasalis ) have been reported [e.g., Bartels, 1937;Medway, 1970;Curtin, 1980;Ruhiyat, 1983;Wakidi, 2013;Rowe and Myers, 2017] although in SouthEast Asian rain forest polyspecific associations between primates are far less common than in African or Neotropical forests [Chapman and Chapman, 2000;Heymann and Buchanan-Smith, 2000;Fam and Nijman, 2011]. It is suggested that polyspecific associations are formed under predation pressure [e.g., Struhsaker, 1981Struhsaker, , 2000Noë and Bshary, 1997].…”

Loud Calls, Startle Behaviour, Social Organisation and Predator Avoidance in Arboreal Langurs (Cercopithecidae: Presbytis)

“…Such conspicuous vocal behaviour is costly both energetically and because it attracts other predators, for example large eagles or felids. Predation on colobines in Asia has been rarely documented [Hart, 2007;Fam and Nijman, 2011]: hawk eagles appear to be an important threat. Hawk eagles mainly adopt a strategy of still hunting, waiting at a perch in the upper canopy for prey (such as langurs) to pass by, and perform a surprise attack from above.…”

“…jumping with stiff legs, branch shaking). Loud calls appear to be elicited by external stimuli such as intergroup encounters, loud calls from neighbouring groups, loud noises, and the appearance of birds of prey or potential terrestrial predators (including humans) [Curtin, 1980;Ruhiyat, 1983;Gurmaya, 1989;Megantara, 1989;Fuentes, 1996;Wich, 2002;Wich and Sterck, 2003;Fam and Nijman, 2011].…”