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Plant taxa identified from seeds recovered from Aotus nigriceps fecal samples. Values are the frequency of occurrence of seeds in recovered samples from each site and sampling occasion. VC = Villa Carmen; MLC = Manu Learning Center; N = fecal sample size.
Source publication
The black-headed night monkey, Aotus nigriceps, has one of the largest distribution ranges of the 11 night monkey species found across Central and South America. Yet, only three studies have focused on their ecology, describing considerable variation in habitat, group composition, and population density. Therefore, we analyzed habitat use, group co...
Contexts in source publication
Context 1
... collected 48 fecal samples (33 from Villa Carmen and 15 from MLC; 26 in spring and 22 in the fall) (Table 1) for a preliminary characterization of diet from identification of deposited seeds. Fecal collection was conducted by covering forest floor with plastic mesh or cloth nets below areas where night monkeys had previously been observed or where there was evidence of their feeding. ...Context 2
... recovered seeds belonging to 12 genera and ten families ( Table 1). The number of taxa recovered from Villa Carmen groups in bamboo forest was similar (N = 10) to that from MLC (N = 8). ...Context 3
... total, we recovered twelve seed types from fecal samples, and only two of these genera were previously described in Aotus (Table 1: Wright 1981 andWright 1985). No other known studies have reported on fruits consumed in other Aotus species. ...Context 4
... collected 48 fecal samples (33 from Villa Carmen and 15 from MLC; 26 in spring and 22 in the fall) (Table 1) for a preliminary characterization of diet from identification of deposited seeds. Fecal collection was conducted by covering forest floor with plastic mesh or cloth nets below areas where night monkeys had previously been observed or where there was evidence of their feeding. ...Context 5
... recovered seeds belonging to 12 genera and ten families ( Table 1). The number of taxa recovered from Villa Carmen groups in bamboo forest was similar (N = 10) to that from MLC (N = 8). ...Citations
... On April 8, 2024, at 12:47 h and 16:10 h, we observed the pair heading towards a sleeping site based on a tree of the species Xilopia aromatica (Annonaceae). The animals were resting and covering themselves with a mixed structure of sticks, leaves, and leaf litter on the ground, a type of structure already documented in trees but different from the usual holes or cavities in trees (Aquino & Encarnación 1986;Case 2013;Helenbrook et al., 2019). Throughout our observations, we identified the male climbing in and out of the trees and returning to the sleeping sites (possibly by the researcher's presence); however, the female remained in the refuge, a possible territorial display like other neotropical primates (Rutberg 1983;Janson, 1986;Spence-Aizenberg et al. 2023; Figure 1; video in Supplementary material, Arango-Lozano 2024). ...
We report a novel observation of ground nesting behavior in a couple of Aotus griseimembra within a successional inter-Andean Forest patch of Colombia. This behavior, previously unrecorded for strictly arboreal primates of the Genus Aotus, challenges conventional understanding. The monkeys exhibited typical species actions but sought refuge on the ground, possibly influenced by habitat alterations. Their visits to the ground sleeping site were monitored and confirmed the vulnerability to predators, competitors in the forest patch. These findings call the attention for further research into the response strategies of neotropical primates to environmental stressors and habitat disturbance.
... Contrastingly, the smaller ones do not require extensive areas of forest and are able to move between patches with small trees, even using the terrestrial stratum (Milton & May, 1976). Due to their ability to move in small trees, smaller primates play a role in the recovery of connectivity and maintenance of the diversity of the Amazon Rainforest in places impacted by humans (Andresen et al., 2018b;Chagas & Ferrari, 2010;Culot et al., 2010;Gestich et al., 2019;Helenbrook et al., 2020;Knogge & Heymann, 2003;Luna et al., 2016;Müller 1996;Oliveira-Silva et al., 2018;Paim et al., 2017;Stone, 2007). ...
Introduction:
Amazonian forests with varying degrees of anthropogenic disturbance in the process of natural regeneration harbour many sympatric primate species. However, studies on their usage by primates are still lacking.
Objective:
To comprehensively study the spatial and temporal dynamics within the primate community in a regenerating forest within the Manu Biosphere Reserve.
Methods:
Two sets of historical data from Crees Foundation for Manu were analyzed, comprising records from January 2011 to February 2023 and corresponding to data obtained through incidental data and Terrestrial In-line Transects in three types of forest with different degrees of historical disturbance.
Results:
Lagothrix lagothricha and Ateles chamek showed a preference for less disturbed forests; Plecturocebus toppini, for more disturbed forests; and the other species did not show a clear preference. Regarding vertical stratification, A. chamek, L. lagothricha and Alouatta sara showed a preference for the upper stratum, P. toppini, Saimiri boliviensis and Sapajus macrocephalus showed a preference for the middle and upper strata and Leontocebus weddelli and Aotus nigriceps, for the middle stratum. According to the temporal activity of each species, seven species (A. chamek, S. macrocephalus, S. boliviensis, P. toppini, L. lagothricha, L. weddelli, and A. sara) were observed during the day, four were similar.
Conclusions:
The primate community varies according to disturbance gradient due to the preferences of some species. The recorded primates make a differentiated use of the vertical strata and most of them show diurnal activity.
... In Peru, it extends into the Andean foothills in the Regions of Madre de Dios and Cuzco, to at least 1,000 m.a.s.l. (Aquino et al. 2013;Gregory et al. 2014;Khimji and Donati 2014;Whitworth et al. 2016;Helenbrook et al. 2020), following this elevation north along the Andean cordillera, through Ucayali, Cerro de Pasco, and Huánuco regions, as far as central San Martín just west of the Rio Huallaga, at ~6°35' S, where it is replaced by A. nancymaae (Shanee et al. 2015;Shanee and Shanee 2018). In Northern Peru, the limit between A. nigriceps and A. nancymaae is suggested to be the Río Aguaytía and its tributaries, the Ríos Pintoyacu and Santa Ana, although the species has been recorded at several sites north and west of those locations. ...
The owl monkeys, genus Aotus, are among the most widely distributed of all platyrrhine genera. The 13 currently recognized taxa are found in Argentina, Bolivia, Brazil, Colombia, Ecuador, Panama, Paraguay, Peru, and Venezuela. They range from lowland tropical moist and dry forests to over 3000 m.a.sl. in the cloud forests of the Andes. Owl monkeys appear to be sufficiently flexible to persist in anthropogenically altered habitats and fragmented forest patches. Here we gathered 1,703 owl monkey localities from a wide range of published and unpublished sources, making the most comprehensive database to date. These records were used to map the distributions of all owl monkey taxa based on our current understanding of the genus. Our knowledge is still limited in many areas where records are lacking, and we caution that all species IDs and maps be treated as tentative until the wide-ranging employment of genetic testing is available.
... Night-vision scopes and other lighting techniques have been used to assist human observations of Aotus in the wild (e.g., Wright 1978Wright , 1989Fernandez-Duque 2003;Fernandez-Duque et al. 2023a this volume), though even this technology cannot resolve the difficulty of seeing through foliage or viewing shy monkeys (Wright 1978). In some cases, more easily observable proxies have been used to study diet and feeding from monkeys that were out of sight (Wright 1978;van der Heide et al. 2012;Helenbrook et al. 2019), and earlier studies used semi-captive animals (Moynihan 1964). Unfortunately, alternative methods aimed at collecting data under the umbrella of "feeding behavior" are not equally useful for building insights into diet, feeding, and the evolution of these animals. ...
Early research hypothesized that Aotus was a member of a specialized guild of hard-fruit and seed-eating “sclerocarpic harvesters” based largely on their dentognathic morphology. However, these food items remain conspicuously absent in reports from the field. Here, we reconsider the morphology of the feeding apparatus of Aotus, in light of the most current ecological and morphological research, and we review functional and phylogenetic themes apparent in the dentition and mandible. Aotus exhibits broad, cebine-like incisors, relatively small, sexually dimorphic canine teeth, and molar morphology that is consistent with a mixed diet of fruit and some structural carbohydrates. The vertical depth of the corpus and other morphological signals in the Aotus mandible are inconsistent with the intensive forms of ingestion and seed predation seen in pitheciids or larger cebines. In sum, though Aotus may occasionally feed on moderately challenging foods, it lacks the morphological specializations associated with sclerocarpic harvesting in platyrrhines.
... Their relatively small body size, cryptic nature, and nocturnality make direct observation extremely difficult (Shanee et al. 2013). They are socially monogamous primates, living in small groups composed of an adult breeding pair and their offspring (Helenbrook et al. 2020). Aotus are predominantly frugivorous (Shanee et al. 2013;Montilla et al. 2021), but also include leaves, seeds, nectar, insects, and flowers (Wright 2011). ...
The black-headed night monkey (Aotus nigriceps) is a predominantly frugivorous nocturnal neotropical primate. As such, records of different dietary items are fundamental. In the present study, we describe the first record of the consumption of Calliandra brevipes inflorescence in the peri-urban, and Cocos nucifera inflorescence, Eugenia uniflora fruits, and arthropods in the urban, region of the city of Porto Velho, in the southwestern Brazilian Amazon
... Aotus nigriceps is a wide-ranging nocturnal monkey species found across much of the central and upper Amazon, including the moist forests of the Southwest Amazon, Jurua-Purus, Purus-Maderia, and Maderia-Tapajos. They are also typically found in degraded forest, agro-forested landscapes, and areas in proximity to humans (Wright 1994;Helenbrook et al. 2020). While night monkeys are adaptable and found to persist in degraded landscapes, they still require connective forest cover, access to seasonally available fruiting trees, sleeping sites, and are restricted by environmental conditions (Aquino and Encarnación 1994;Helenbrook et al. 2020). ...
... They are also typically found in degraded forest, agro-forested landscapes, and areas in proximity to humans (Wright 1994;Helenbrook et al. 2020). While night monkeys are adaptable and found to persist in degraded landscapes, they still require connective forest cover, access to seasonally available fruiting trees, sleeping sites, and are restricted by environmental conditions (Aquino and Encarnación 1994;Helenbrook et al. 2020). Although thought to be a common species, it is currently listed as Appendix II of CITES [Convention on International Trade in Endangered Species of Wild Fauna and Flora], and the impact of anthropogenic disturbances on the long-term viability of A. nigriceps remains unknown. ...
... However, discrepancies remain regarding the extent of their eastern distribution in the state of Rondonia, and additional taxonomic analysis is needed from the area (e.g., Pieczarka et al. 1993;Plautz et al. 2009;Menezes et al. 2010;Babb et al. 2011;Ruiz-Garcia et al. 2011). The species is not considered under threat due to their presumed extensive range, their large and sustained population size (Shanee et al. 2018), and highdensity estimates ranging from 19 to 50 individuals/km 2 (Helenbrook et al. 2020). However, no known population size estimates or trends have been described despite large portions of the range of A. nigriceps overlapping with areas experiencing some of the highest deforestation rates in the world (Estrada et al. 2018). ...
Deforestation rates in the Brazilian Amazon have been steadily increasing since 2007. Recent government policy, the projected growth of agriculture, and the expansion of the cattle industry are expected to further pressure primates within the Amazon basin. In this study, we examined the anthropogenic impact on the widely distributed black-headed night monkey, Aotus nigriceps, whose distribution and population status have yet to be assessed. We (1) modeled potential species distribution in A. nigriceps, (2) estimated the impact of habitat loss on population trends, and (3) highlight landscape-based conservation actions that maximize the potential for their long-term sustainability. We found the black-headed night monkey to be restricted by several biotic and environmental factors including forest cover, isothermality, precipitation, temperature, and elevation. Over the last two decades, over 132,908 km2 of tree cover (18%) has been lost within their currently recognized range based on satellite imagery. Based on a balance training omission, predicted area, and threshold values (BPTP), suitable habitat was only 67% (1,069,948 km2) of their hypothesized range, a loss of 16.5% from 2000, with just nearly a third of suitable habitat currently within protected areas. Over the last two decades, an estimated minimum 1.6 million individuals have been lost due to loss of suitable habitat. Projected deforestation rates equate to an additional loss of 94,458 km2 of suitable habitat over the next decade. Although classified as a species of Least Concern, we suggest that A. nigriceps may likely be more at risk than previously described. The future impact of the continued expansion of monoculture crops, cattle ranching, and wildfires is still unknown. However, we outline several steps to ensure the long-term viability of this nocturnal primate and other sympatric species throughout the Amazon Basin.
... lemurinus) and lowland (A. nigriceps) night monkeys, even if it is not as diverse as other families and is less consumed by other American primates (Castaño et al. 2010;Guzmán et al. 2016;Helenbrook et al. 2019;de Luna et al. 2017). Among the family Urticaceae, night monkeys mainly consume the genus Cecropia (Castaño et al. 2010;Guzmán et al. 2016;Helenbrook et al. 2019), which all four study groups consumed in high percentages. ...
... nigriceps) night monkeys, even if it is not as diverse as other families and is less consumed by other American primates (Castaño et al. 2010;Guzmán et al. 2016;Helenbrook et al. 2019;de Luna et al. 2017). Among the family Urticaceae, night monkeys mainly consume the genus Cecropia (Castaño et al. 2010;Guzmán et al. 2016;Helenbrook et al. 2019), which all four study groups consumed in high percentages. ...
Most primates live in lowland ecosystems; however, some species have been particularly successful at colonizing higher altitudes, such as night monkeys (genus Aotus). Studies of the ecology of night monkeys in tropical forests are numerous, but behavioral data are limited due to the challenges associated with their nocturnal habits. Although Andean night monkeys (A. lemurinus) live in mountain forests >1000 m.a.s.l. and Caribbean night monkeys (A. griseimembra) live in rainforests <1000 m.a.s.l., they are found at similar tropical latitudes. Between 2018 and 2019, we followed three groups of A. lemurinus and one group of A. griseimembra at three sites in Colombia and recorded data on their ecology and behavior. Although they live at different altitudes, the two species had similar activity patterns and diet, investing approximately half of the night in resting (48%), and feeding primarily on fruits. We found differences among groups in the time invested in feeding on flowers, their home range, and distance traveled per night. These differences may be related to the unique characteristics of each study site and differences in resource availability and floristic composition of forests at different altitudes. Although the most important families in their diet were Moraceae and Urticaceae, highland groups also fed frequently on a large number of Melastomataceae and Rubiaceae trees. This research suggests these two nocturnal primates, living in contrasting environments, use similar strategies to cope with the challenges of being active at night in tropical forests.
... Aotus nigriceps is a wide-ranging nocturnal monkey species which lives in degraded habitats, utilizes agroforested landscapes, and is known to tolerate human populations (Helenbrook et al., 2020). Nevertheless, while night monkeys are adaptable and persist in degraded landscapes, they still require connective forest cover, access to seasonally available 60 fruiting trees, sleeping sites, and are restricted by environmental conditions (Wright 1981;Aquino & Encarnación 1994;Fernandez-Duque et al., 2001;Helenbrook et al., 2020). ...
... Aotus nigriceps is a wide-ranging nocturnal monkey species which lives in degraded habitats, utilizes agroforested landscapes, and is known to tolerate human populations (Helenbrook et al., 2020). Nevertheless, while night monkeys are adaptable and persist in degraded landscapes, they still require connective forest cover, access to seasonally available 60 fruiting trees, sleeping sites, and are restricted by environmental conditions (Wright 1981;Aquino & Encarnación 1994;Fernandez-Duque et al., 2001;Helenbrook et al., 2020). This species is found in Southern Peru, northern Bolivia, and central-western Brazil with density estimates ranging from 19-50 individuals/km 2 (Helenbrook et al., 2020). ...
... Nevertheless, while night monkeys are adaptable and persist in degraded landscapes, they still require connective forest cover, access to seasonally available 60 fruiting trees, sleeping sites, and are restricted by environmental conditions (Wright 1981;Aquino & Encarnación 1994;Fernandez-Duque et al., 2001;Helenbrook et al., 2020). This species is found in Southern Peru, northern Bolivia, and central-western Brazil with density estimates ranging from 19-50 individuals/km 2 (Helenbrook et al., 2020). The International Union for Conservation of Nature (IUCN) currently lists this species as Least Concern because of their 65 extensive range, suspected large and sustained population size, and presumed low risk of extinction. ...
Deforestation rates in the Brazilian Amazon have been steadily increasing since 2007. Recent government policy, projected growth of agriculture, and expansion of the cattle industry is expected to further pressure primates within the Amazon basin. In this study, we examined the anthropogenic impact on the widely distributed black-headed night monkey, Aotus nigriceps, whose distribution and population status have yet to be assessed. We 1) modeled species distribution in A. nigriceps; 2) estimated impact of habitat loss on population trends; and 3) highlight landscape-based conservation actions which maximize potential for their long-term sustainability. We found the black-headed night monkey to be restricted by several biotic and environmental factors including forest cover, elevation, isothermality, and precipitation. Over the last two decades, over 132,908 km2 of tree cover (18%) has been lost within their documented range. We found this species occupies only 49% of habitat within in their range, a loss of 19% from their estimated 2000 distribution, and just over 34% of occupied areas were in protected areas. Projected deforestation rates of A. nigriceps equates to an additional loss of 23,084 km2 of occupied habitat over the next decade. This study suggests that although classified as a species of Least Concern, A. nigriceps may have a much smaller range and is likely more at risk than previously described. The future impact of continued expansion of mono-cultured crops, cattle ranching, and wildfires is still unknown. However, expanded use of participatory REDD+, sustainable agroforestry in buffer zones, secured land tenor for indigenous communities, wildlife corridors, and the expansion of protected areas can help ensure viability for this nocturnal primate and other sympatric species throughout the Amazon Basin.
... The black-headed night monkey, Aotus nigriceps, is found in the central and upper Amazon, including Brazil, Bolivia, and Peru. This species can be found in both disturbed and undisturbed forests, living in high densities even in heavily disturbed areas (Aquino and Encarnacion 1994;Helenbrook et al. 2020). Although A. nigriceps are currently listed as Least Concern (Shanee et al. 2018), there is evidence to suggest that their numbers are dwindling quickly due to large-scale forest degradation and conversion, especially in the Brazilian Amazon which explains its current Appendix II listing in the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES [https://cites.org/eng/node/19663]). ...
The study of intestinal parasite communities is an important aspect of conservation biology, disease ecology, and wildlife health. Researchers can use the presence of select micro-and macro-parasites as an indicator of host health. Only two studies have sampled intestinal parasites in free-ranging Aotus monkeys despite their wide geographic distribution in Central and South America. We therefore conducted a survey of gastrointestinal parasites using 50 fecal samples from seven free-ranging black-headed night monkey (Aotus nigriceps) groups at three field sites in the Peruvian Amazon. We calculated an index of habitat quality using Gentry transects and compared this with parasite communities. We recovered seven intestinal parasite taxa: Strongyloides sp., Balantioides sp., Trypanoxyuris sp., Entamoeba sp., unidentified species of ascarid, strongylid, and trematode. Two of these taxa have previously been described in captive A. nigriceps (Balantioides sp. and Strongyloides sp.). Parasite richness ranged 0-5 taxa with a mean of 0.8 parasite taxa (±1.0 SD) per fecal sample. Fifty-six percent of samples had at least one intestinal parasite taxon. We found all seven parasite taxa in the wet season but only Strongyloides sp. and Trypanoxyuris sp. in the dry season. Balantioides sp. was positively associated with both Entamoeba sp. and an unidentified trematode, while Entamoeba sp. was positively associated with the unidentified ascarid (p<0.05). Extrapolations support the likelihood of recovering additional intestinal parasite taxa with increased sampling effort. Neither group size nor basal area was significantly associated with parasite richness. These results highlight the need for continued surveillance of Aotus parasites both temporally and across heterogeneous landscapes because several of the parasite taxa we found are pathogenic in nonhuman primates and people.
... De la familia Moraceae, consumieron principalmente frutos y ocasionalmente hojas y flores, lo cual podría estar relacionado a las características carnosas de los frutos de esta familia, los cuales están adaptados a la atracción de animales que potencialmente dispersan sus semillas (Gentry, 1982). Adicionalmente, estos frutos contienen grandes concentraciones de ácido ascórbico el cual es indispensable en la dieta de los primates (Milton, 1987(Milton, ,1993Serio-Silva, 2002 (Castaño et al. 2010;Guzmán et al., 2016;Helenbrook et al., 2019). En el caso de los dos grupos de monos nocturnos de Pijao, una de las especies más consumidas fue Cecropia telealba. ...
Las dinámicas ecológicas asociadas a los comportamientos de selección de recursos han sido uno de los aspectos mejor estudiados en primates neotropicales. Sin embargo, históricamente estas investigaciones se han enfocado en abordar aspectos descriptivos, en los que usualmente se ha ignorado el subyacente componente evolutivo, fundamental para entender plenamente la selección de recursos como proceso. Por su hábito nocturno y rango de distribución en ecosistemas de montaña, los monos nocturnos andinos (Aotus lemurinus) plantean interrogantes singulares sobre los elementos que determinan los patrones conductuales asociados a la selección de recursos. En este estudio describimos la ecología básica de dos grupos familiares de A. lemurinus (PI1 y PI2) de un fragmento de bosque subandino en el municipio de Pijao-Quindío, Colombia. Adicionalmente, evaluamos la preferencia en la selección de frutos, o si su consumo depende de su disponibilidad en el hábitat. Este estudio acumuló 1134 horas de seguimiento, divididas entre los dos grupos familiares en 583 para PI1 y 551 para PI2. Se obtuvieron 1027 registros de actividad, divididos en 460 para PI1 y 567 para PI2. Los dos grupos familiares invirtieron la mayor parte de su tiempo en descanso (PI1 38.1% - PI2 53.1%), seguido por alimentación (PI1 33.2% - PI2 20.8%) y movimiento (PI1 27.5% - PI2 25.7%), las actividades de interacciones sociales y otras estuvieron representadas en menos del 1% del presupuesto de tiempo total. Identificamos 29 especies de plantas con frutos en la dieta de los grupos evaluados, documentando una preferencia de consumo por plantas asociadas filogenéticamente a la subclase Rosidae, reforzando la hipótesis que las especies de plantas filogenéticamente cercanas comparten características funcionales que las hacen predilectas para los dispersores.
