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ABSTRACT Plecturocebus ornatus is an endemic vulnerable species due to its population decline and its restricted range within the Eastern Plains of Colombia. This region is affected by deforestation as a result of legal and illegal economic activities. The aim of this work was to analyze the presence and abundance of P. ornatus during a period of urban and livestock production expansion (1986-2019) in Villavicencio, Colombia. This municipality is the most affected by land-use changes associated with regional economic development and represents 3.4 % of P. ornatus distribution's area. The analysis was performed using satellite images Landsat 4 and 8, with V-Late in ArcGIS 10.5 to describe landscape structure, and P. ornatus occurrence records, obtained through field observations and the Global Biological Information Facility. Densities were calculated for each fragment based on total individuals observed by transect. A generalized lineal model was used to evaluate the effects of patch-scale, landscape-scale and other variables on P. ornatus abundance. By 1986 the rural and peri-urban areas of Villavicencio were already a transformed landscape. During the analyzed period, landscape was predominantly made up of disconnected linear fragments with a secondary humid forest cover. Around 82.1 % of the fragments with P. ornatus records are threatened by urbanization and only 50 % are in protected areas. Densities varied from 0.00 to 7.26 ind/ha (0.00-726.82 ind/km2). Abundance of P. ornatus was highly influenced by landscape-scale variables related with landscape connectivity, as well as fragment area and number of other primate species. Therefore, the implementation of restoration measures that increase landscape connectivity and habitat availability is proposed, as well as more control over environmental land-use planning, to contribute to the conservation of P. ornatus in urban areas.

RESUMEN Plecturocebus ornatus es una especie endémica vulnerable debido a la disminución de su población y distribución restringida al piedemonte de los Llanos Orientales Colombianos. Esta región es afectada por la deforestación resultante de actividades económicas legales e ilegales. El objetivo de este trabajo fue analizar la presencia y abundancia de P. ornatus durante un período de expansión urbana y ganadera (1986-2019) en Villavicencio, Colombia. Este municipio es el más afectado por cambios de uso del suelo asociados al desarrollo económico regional y representa el 3,4 % del área de distribución de P. ornatus. El análisis se realizó a partir de imágenes satelitales Landsat 4 y 8, con V-Late de ArcGIS 10.5, para describir la estructura del paisaje, y registros de P. ornatus obtenidos en observaciones de campo y del Global Biological Information Facility. Se calcularon densidades de cada fragmento basadas en el número total de individuos observados. Un modelo lineal generalizado fue usado para evaluar el efecto de variables a la escala del parche, paisaje y otros sobre la abundancia de P. ornatus. Para 1986 los sectores rurales y periurbanos de Villavicencio ya eran un paisaje transformado. Durante el período analizado, el paisaje estuvo predominantemente conformado por fragmentos lineales desconectados con cobertura de bosque húmedo secundario. Alrededor del 82,1 % de los fragmentos con registros de P. ornatus están amenazados por la urbanización y solo el 50 % se encuentran en áreas protegidas. Las densidades variaron de 0,00 to 7,26 ind/ha (0,00-726,82 ind/km2). La abundancia de P. ornatus fue altamente influenciada por variables a la escala de paisaje relacionadas con la conectividad del paisaje, así como el área del fragmento y la presencia de otras especies de primates. Por lo tanto, la implementación de medidas de restauración que incrementen la conectividad del paisaje y disponibilidad de hábitat, así como un mayor control sobre el ordenamiento territorial ambiental, pueden contribuir a la conservación de P. ornatus en áreas urbanas.

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Acoustic signals are ubiquitous across mammalian taxa. They serve a myriad of functions related to the formation and maintenance of social bonds and can provide conspecifics information about caller condition, motivation and identity. Disentangling the relative importance of evolutionary mechanisms that shape vocal variation is difficult, and little is known about heritability of mammalian vocalizations. Duetting--coordinated vocalizations within male and female pairs--arose independently at least four times across the Primate Order. Primate duets contain individual- or pair-level signatures, but the mechanisms that shape this variation remain unclear. Here, we test for evidence of heritability in two call types (pulses and chirps) from the duets of captive coppery titi monkeys (Plecturocebus cupreus). We extracted four features--note rate, duration, minimum and maximum fundamental frequency--from spectrograms of pulses and chirps, and estimated heritability of the features. We also tested whether features varied with sex or body weight. We found evidence for moderate heritability in one of the features examined (chirp note rate), whereas inter-individual variance was the most important source of variance for the rest of the features. We did not find evidence for sex differences in any of the features, but we did find that body weight and fundamental frequency of chirp elements covaried. Kin recognition has been invoked as a possible explanation for heritability or kin signatures in mammalian vocalizations. Although the function of primate duets remains a topic of debate, the presence of moderate heritability in titi monkey chirp elements indicates duets may serve a kin recognition function.

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Following behavior is a well-documented foraging specialization in Neotropical birds, which consists of individuals of solitary or mixed-flocking species following other moving animals to capture fleeing prey. Here, we report two observations of the cryptic forest-falcon, Micrastur mintoni following troops of primates during an ornithological inventory in the eastern Brazilian Amazon. During both observations, the falcon emitted a typical vocalization and captured fleeing insects dispersed by the primates moving through the forest while foraging. This is the first report of an apparently commensal association between a Micrastur forest falcon and two species of primates.(AU)

O comportamento de following é uma especialização de forrageamento bem documentada em aves neotropicais, que consiste em indivíduos de espécies solitárias ou em bandos mistos seguindo outros animais em movimento para capturar presas afugentadas. Aqui reportamos duas observações do falcão-críptico, Micrastur mintoni seguindo grupos de primatas, durante um inventário ornitológico na Amazônia oriental brasileira. Durante as duas observações, o falcão emitiu uma vocalização típica e capturou insetos afugentados pelos primatas em movimento pela floresta enquanto forrageavam. Esse é o primeiro relato de uma associação aparentemente comensal entre um falcão florestal do gênero Micrastur e duas espécies de primatas.(AU)

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Worldwide urban expansion and deforestation have caused a rapid decline of non-human primates in recent decades. Yet, little is known to what extent these animals can tolerate anthropogenic noise arising from roadway traffic and human presence in their habitat. We studied six family groups of titis residing at increasing distances from a busy highway, in a park promoting ecotourism near Santa Cruz de la Sierra, Bolivia. We mapped group movements, sampled the titis' behavior, collected fecal samples from each study group and conducted experiments in which we used a mannequin simulating a human intrusion in their home range. We hypothesized that groups of titi monkeys exposed to higher levels of anthropogenic noise and human presence would react weakly to the mannequin and show higher concentrations of fecal cortisol compared with groups in least perturbed areas. Sound pressure measurements and systematic monitoring of soundscape inside the titis' home ranges confirmed the presence of a noise gradient, best characterized by the root-mean-square (RMS) and median amplitude (M) acoustic indices; importantly, both anthropogenic noise and human presence co-varied. Study groups resided in small, overlapping home ranges and they spent most of their time resting and preferentially used the lower forest stratum for traveling and the higher levels for foraging. Focal sampling analysis revealed that the time spent moving by adult pairs was inversely correlated with noise, the behavioral change occurring within a gradient of minimum sound pressures ranging from 44 dB(A) to 52 dB(A). Validated enzyme-immunoassays of fecal samples however detected surprisingly low cortisol concentrations, unrelated to the changes observed in the RMS and M indices. Finally, titis' response to the mannequin varied according to our expectation, with alarm calling being greater in distant groups relative to highway. Our study thus indicates reduced alarm calling through habituation to human presence and suggests a titis' resilience to anthropogenic noise with little evidence of physiological stress.

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O uso de redes de neblina é um método altamente utilizado entre os pesquisadores devido a sua eficiência na captura de aves e morcegos. No entanto, os animais presos ficam vulneráveis à ação de predadores. Durante a realização de três estudos ornitológicos realizados em um fragmento florestal no sudoeste da Amazônia, foram registrados 15 eventos de predação, com taxa de predação de 1,5%. Entre os predadores, 26,7% (n = 4) dos casos foram relacionados com primatas, 13,3% (n = 2) relacionados com formigas de correição, 13,3% (n = 2) relacionados com uma espécie de gavião não identificado e em 46,7% (n = 7) dos casos os predadores não foram identificados. Evitar o acesso de predadores às redes de neblina e diminuir o tempo de monitoramento das redes são algumas das medidas que podem evitar estes eventos.

The use of mist nets is a highly used method among researchers due to their efficiency in capture birds and bats. However, trapped animals are vulnerable to predator action. During three ornithological studies carried out in a forest fragment from southwest Amazonia, we recorded 15 predation events, with predation rate of 1.5%. Among predators, 26.7% (n = 4) of the cases were related to primates, 13.3% (n = 2) related to army ants, 13.3% (n = 2) related to an unidentified hawk species and in 46.7% (n = 7) of the cases the predators did not identified. Preventing predator access to mist nets and reducing network monitoring time are some of the measures that can prevent these events.

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O uso de redes de neblina é um método altamente utilizado entre os pesquisadores devido a sua eficiência na captura de aves e morcegos. No entanto, os animais presos ficam vulneráveis à ação de predadores. Durante a realização de três estudos ornitológicos realizados em um fragmento florestal no sudoeste da Amazônia, foram registrados 15 eventos de predação, com taxa de predação de 1,5%. Entre os predadores, 26,7% (n = 4) dos casos foram relacionados com primatas, 13,3% (n = 2) relacionados com formigas de correição, 13,3% (n = 2) relacionados com uma espécie de gavião não identificado e em 46,7% (n = 7) dos casos os predadores não foram identificados. Evitar o acesso de predadores às redes de neblina e diminuir o tempo de monitoramento das redes são algumas das medidas que podem evitar estes eventos.(AU)

The use of mist nets is a highly used method among researchers due to their efficiency in capture birds and bats. However, trapped animals are vulnerable to predator action. During three ornithological studies carried out in a forest fragment from southwest Amazonia, we recorded 15 predation events, with predation rate of 1.5%. Among predators, 26.7% (n = 4) of the cases were related to primates, 13.3% (n = 2) related to army ants, 13.3% (n = 2) related to an unidentified hawk species and in 46.7% (n = 7) of the cases the predators did not identified. Preventing predator access to mist nets and reducing network monitoring time are some of the measures that can prevent these events.(AU)

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The taxonomy of the titi monkeys (Callicebinae) has recently received considerable attention. It is now recognised that this subfamily is composed of three genera with 33 species, seven of them described since 2002. Here, we describe a new species of titi, Plecturocebus, from the municipality of Alta Floresta, Mato Grosso, Brazil. We adopt an integrative taxonomic approach that includes phylogenomic analyses, pelage characters, and locality records. A reduced representation genome-wide approach was employed to assess phylogenetic relationships among species of the eastern Amazonian clade of the Plecturocebus moloch group. Using existing records, we calculated the Extent of Occurrence (EOO) of the new species and estimated future habitat loss for the region based on predictive models. We then evaluated the species' conservation status using the IUCN Red list categories and criteria. The new species presents a unique combination of morphological characters: (1) grey agouti colouration on the crown and dorsal parts; (2) entirely bright red-brown venter; (3) an almost entirely black tail with a pale tip; and (4) light yellow colouration of the hair on the cheeks contrasting with bright red-brown hair on the sides of the face. Our phylogenetic reconstructions based on maximum-likelihood and Bayesian methods revealed well-supported species relationships, with the Alta Floresta taxon as sister to P. moloch + P. vieirai. The species EOO is 10,166,653 ha and we predict a total habitat loss of 86% of its original forest habitat under a "business as usual" scenario in the next 24 years, making the newly discovered titi monkey a Critically Endangered species under the IUCN A3c criterion. We give the new titi monkey a specific epithet based on: (1) clear monophyly of this lineage revealed by robust genomic and mitochondrial data; (2) distinct and diagnosable pelage morphology; and (3) a well-defined geographical distribution with clear separation from other closely related taxa. Urgent conservation measures are needed to safeguard the future of this newly discovered and already critically endangered primate.

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Long-range vocal communication in socially monogamous titi monkeys is mediated by the production of loud, advertising calls in the form of solos, duets, and choruses. We conducted a power spectral analysis of duets and choruses (simply "duets" hereafter) followed by linear discriminant analysis using three acoustic parameters-dominant frequency of the combined signal, duet sequence duration, and pant call rate-comparing the coordinated vocalizations recorded from 36 family groups at 18 sites in Bolivia, Peru and Ecuador. Our analysis identified four distinct duetting patterns: (1) a donacophilus pattern, sensu largo, characteristic of P. donacophilus, P. pallescens, P. olallae, and P. modestus; (2) a moloch pattern comprising P. discolor, P. toppini, P. aureipalatii, and P. urubambensis; (3) a torquatus pattern exemplified by the duet of Cheracebus lucifer; and (4) the distinctive duet of P. oenanthe, a putative member of the donacophilus group, which is characterized by a mix of broadband and narrowband syllables, many of which are unique to this species. We also document a sex-related difference in the bellow-pant phrase combination among the three taxa sampled from the moloch lineage. Our data reveal a presumptive taxonomic incoherence illustrated by the distinctive loud calls of both P. urubambensis and P. oenanthe within the donacophilus lineage, sensu largo. The results are discussed in light of recent reassessments of the callicebine phylogeny, based on a suite of genetic studies, and the potential contribution of environmental influences, including habitat acoustics and social learning. A better knowledge of callicebine loud calls may also impact the conservation of critically endangered populations, such as the vocally distinctive Peruvian endemic, the San Martin titi, P. oenanthe.

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Maintaining a constant body temperature is critical to the proper functioning of metabolic reactions. Behavioural thermoregulation strategies may minimize the cost of energetic balance when an animal is outside its thermoneutral zone. We investigated whether ambient temperature and relative air humidity influence the use of behavioural strategies by a group of Prince Bernhard's titi monkeys (Callicebus bernhardi) living in a forest fragment. We monitored a social group composed of four individuals (an adult couple and two juveniles) for 1010h from March to September 2015. We used the instantaneous scan sampling method to record the body posture, the microhabitat, and the occurrence of huddling with group mate(s) when animals were resting. We recorded ambient temperature and relative humidity in the shade every 10min with a data logger hanging at a height of approximately 5m. Daytime temperature ranged from 18.5°C to 38.5°C and relative humidity ranged from 21% to 97%. Titi monkeys avoided sunny places at higher temperatures, especially above 31°C. Minimum night temperature did not influence the choice of resting microhabitats during the first hour after sunrise. Sitting was the major resting posture during the day (62%). Titi monkeys increased the use of heat-dissipating postures at ambient temperatures >27°C. In addition, an increase in relative humidity increased the use of these postures at 26°C, 27°C, 29°C and 33°C, but caused a decrease at 24°C. On the other hand, the ambient temperature did not influence the occurrence of huddling. We conclude that microhabitat choice and postural behaviour are important for titi monkeys to prevent overheating and suggest that these behavioural adjustments might also be critical for other tropical arboreal mammals.

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