Aotus azarae (Humboldt, 1812)

Russell A. Mittermeier, Anthony B. Rylands & Don E. Wilson, 2013, Aotidae, Handbook of the Mammals of the World – Volume 3 Primates, Barcelona: Lynx Edicions, pp. 414-431 : 430-431

publication ID 10.5281/zenodo.5726960


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scientific name

Aotus azarae


11 View On . Azara’s Night Monkey Aotus azarae View in CoL

French: Douroucouli de d'Azara / German: Azara-Nachtaffe / Spanish: Mico nocturno de Azara Other common names: Azara's Owl Monkey; Bolivian Night Monkey (boliviensis), Feline Night Monkey (infulatus)

Taxonomy. Simia azarae Humboldt, 1812 View in CoL ,

Paraguay. Restricted by Elliot in 1913 to the right bank of Rio Paraguay in northeastern Argentina.

Three subspecies are recognized.

Subspecies and Distribution. A. a. azarae Humboldt, 1812 — SC Brazil (Pantanal), S Bolivia (Banados del Izozog), Paraguay (S & W Chaco, W of the Rio Paraguay), and N Argentina (provinces of Chaco & Formosa).

A. a. boliviensis Elliot, 1907 — SE Peru (S of the rios Madre de Dios and Inambari) and Bolivia E of the Andes (from the Rio Madre de Dios S to the Banados del Izozog in the border region with Paraguay). A. a. infulatus Kuhl, 1820 — Brazil, S of the Rio Amazonas (but with a small enclave in the SE tip of Amapa State), including Marajo and Caviana Is, extending E in the state of Maranhao as far as the Rio Parnaiba, S along the W bank of Rio Tocantins to the Pantanal of Mato Grosso, W limits are marked by the rios Tapajos and Juruena. View Figure

Descriptive notes. Head-body 34 cm (males) and 33 cm (females), tail ¢.31 cm; weight 990-1580 g (males, nominate subspecies) and 1010-1450 g (female nominate subspecies). Azara’s Night Monkey is a highly variable red-necked species, with a diploid chromosome number of 49 in males and 50 in females. An interscapular whorl is generally present. In the subspecies azarae , fur is long, thick, and shaggy, grayish to pale buffyagouti above and pale whitish-orange below. Face stripes are narrow. Basal hairs of the distal one-quarter of tail are orange. In the “Bolivian Night Monkey” (A. a. bolivienss), fur is relatively short, with an olive tone above and contrastingly grayer on limbs. Face stripes are very narrow except where the middle one expands on the crown; the black temporal stripe is poorly defined, the black malar stripe is faint or absent, and there is usually a whitish band between the eyes and temporal stripe. There is a conspicuous whorl between the shoulder blades. The “Feline Night Monkey” (A. a. infulatus) is like the Bolivian Night Monkey, but the white on its face is more prominent. There is generally no whitish band between the eyes and the temporal stripe as with the Bolivian Night Monkey. Temporal stripes are black, well defined, and continuous with the malar stripe. The tail tends to be reddish throughout its length except for the black tip. Orange of underparts extends to or above the ventral one-half of side of neck and to mid-tibia or ankle. Color of the throat varies from orange, with the anterior one-half grayish agouti to entirely orange. Sometimes there is an interscapular whorl, sometimes not.

Habitat. Deciduous, gallery, riparian, and secondary forest of the Chaco in Paraguay, Bolivia, and northern Argentina. Group sizes of Azara’s Night Monkey are smaller in the more xeric regions of the Chaco compared with humid (mesic) regions. Seasonality in these environments is strong, and temperatures range between —=5°C and 47°C. The Feline Night Monkey has been recorded in Orbignya ( Arecaceae ) palm forest (the Zona dos Cocais in Maranhao), forest patches and gallery forests in the “cerrado” (bush savanna) of central Brazil, and the “caatinga” (deciduous scrub and forest) in north-eastern Brazil. It also occurs in mangrove forest.

Food and Feeding. Diet of Azara’s Night Monkey is composed of fruits, nectar, flowers, leaves, fungi, and insects. Feeding ecology of the nominate subspecies has been studied in the subtropical dry forest of Paraguay. Azara’s Night Monkeys there were more folivorous than the Black-headed Night Monkey (A. nigriceps ) in Peru, concentrating on leaves of small trees and vines for 46% of their feeding time and with fruit being only 16% of the diet (as opposed to 60%), and nectar and flowers 33%. At times of fruit shortage, Black-headed Night Monkeys eat more flowers, nectar, fig fruits, and insects, rather than leaves. Flowers can also be seasonally important, for example those of Tabebuia ipe ( Bignoniaceae ). Azara’s Night Monkeys have been seen to catch cicadas during the day.

Breeding. Breeding of Azara’s Night Monkey is seasonal; births peak in January-February in Paraguay and October-November in Argentina. In Argentina, adult body mass is reached at about four years of age, and the onset of reproduction occurs at about six years. In the nominate subspecies azarae , females have a reproductive cycle of ¢.22 days in the wild and 25 days in captivity. Captive and wild females of the subspecies azarae have a gestation period of ¢.120-130 days. Infants are mostly carried by the male from when they are about ten days old. The median interbirth interval is 370 days (range 345-426 days, n = 13). As has been found for other night monkeys, mating is infrequent. During three years of study and more than 2000 hours of observations, mating was recorded only eight times in five groups. Itis rapid and discreet, and therefore difficult to observe. Although all night monkeys are believed to be monogamous (there is never more than one breeding female and always only one male in the groups), a long-term study of known individuals in a population of the subspecies azarae in northern Argentina showed considerable turnover of resident adults.

Activity patterns. In Paraguay, the nominate subspecies is partially diurnal, foraging during the day for periods of one to three hours. Large raptors such as the harpy eagle (Harpia harpyja) and the Guiana crested eagle (Morphnus guianensis) are rare there, and the principal, potential, avian predator is the great horned owl (Bubo virgintanus). When traveling at night, they are quieter than is typical for night monkeys of the Amazonian forest possibly because of this. Temperature may be another factor promoting diurnal activity. Low temperatures do not completely inhibit their traveling and foraging, but when night-time temperatures are 5°-10°C, they forage in the late afternoon at temperatures of 25°-30°C. Diurnal foraging and traveling increases when the weather is cooler. A field study of the subspecies Bolivian Night Monkey in Beni, Bolivia, recorded an activity budget of 31% foraging, 49% resting, and 20% traveling. Groups travel longer during full-moon nights than new-moon nights, and ambient temperature also influences distances moved during full-moon nights.

Movements, Home range and Social organization. Social structure of Azara’s Night Monkey consists of one adult male and one adult female per group, with a mean group size of 2-3-4 individuals. Subadults are often observed in groups of the nominate subspecies azarae in Argentina. Group density of the subspecies azarae has been reported at 5-5-16 groups/km? in Argentina. In Paraguay, group density has been estimated at 4 groups/km”. For the Bolivian Night Monkey, there is one report of 68-9 groups/ km?, but the census was taken in an island offorest of only 0-33 ha. Home-range size has been reported to vary from 5 ha to 10 ha. Mean daily movement is estimated at 378-5 m, with mean diurnal movement of 199 m and mean nocturnal movement of 420 m. The population of the subspecies azarae in Guaycolec Ranch, Formosa Province, Argentina, has ¢.25-30% of adults living solitarily. Both males and females disperse. Subadults are often on the periphery of a social group’s home range prior to emigration in the subspecies azarae . Turnover of resident adults is frequent, with 14 of 15 pairs replacing at least one adult in a three-year period. Aggressive interactions in this population are observed between groups during the day and night. Paternal care and provisioning have been observed, with males carrying an infant 84% of the time after the first week oflife. The adult male also plays, grooms, and shares food with the infant. In the subspecies azarae , males and females share food in the wild with infants and mates. Individuals in the population at Guaycolec often travel on the ground when they cross from one patch of forest to the other, sometimes for distances up to 100 m.

Status and Conservation. CITES Appendix II. Classified as Least Concern on The IUCN Red List. Subspecies azarae and boliviensis are classified as Least Concern and subspecies infulatus is classified as Near Threatened because of logging and the widespread conversion of forest for commercial agriculture, especially for soy beans, and for cattle pasture throughout its range in northern Mato Grosso and southern Para over the last two decades. The range of Azara’s Night Monkey coincides with the most devastated areas of the Brazilian Amazon. The subspecies azarae occurs in the national parks of Rio Pilcomayo in Argentina and Kaa-lya del Gran Chaco in Bolivia, and in the Defensores del Chaco, and Tinfunqué national parks in Paraguay. The Bolivian Night Monkey occurs in Amboro, Carrasco, Isiboro Sécure, Madidi, and Noel Kempff Mercado national parks and Pilon Lajas Biosphere Reserve in Bolivia. The Feline Night Monkey occurs in Pantanal Matogrossense and Araguaia national parks and Gurupi and Tapirapé biological reserves in Brazil.

Bibliography. Arditi (1992), Arditi & Placci (1990), Defler et al. (2001), Dixson (1983, 1994), Fernandes (1993), Fernandez-Duque (2003, 2004, 2011a, 2011b, 2012), Fernandez-Duque & Bravo (1997), Fernandez-Duque & Erkert (2004, 2006), Fernandez-Duque & Huntington (2002), Fernandez-Duque, Rotundo & Ramirez-Llorens (2002), Fernandez-Dugue, Rotundo & Sloan (2001), Fernandez-Duque, Wallace & Rylands (2008), Garcia & Braza (1987, 1989, 1993), Giménez & Fernandez-Duque (2003), Huck & Fernandez-Duque (2011), Huck et al. (2011), Hunter et al. (1979), Jantschke et al. (1998), Ma, Elliott et al. (1976), Ma, Jones et al. (1976), Mudry, Colillas & de Salum (1984), Mudry, Slavutsky & Labal de Vinuesa (1990), Pieczarka & Nagamachi (1988), Pieczarka et al. (1993), Rathbun & Gache (1980), Rotundo et al. (2005), Silva & Fernandes (1999), Silva & Nunes (1995), Smith & Jungers (1997), Stallings et al. (1989), Welker et al. (1998), Wolovich & Evans (2007), Wolovich, Perea-Rodriguez & Fernandez-Duque (2008), Wright (1981, 1985, 1989, 1994), Zunino (1985), Zunino et al. (1986).














Aotus azarae

Russell A. Mittermeier, Anthony B. Rylands & Don E. Wilson 2013

Simia azarae

Humboldt 1812
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