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Parallel laser photogrammetry (PLP), which consists of attaching two or three parallel laser beams at a known inter-beam distance to a camera, can be used to collect morphological measurements of organisms noninvasively. The lasers project onto the photo being taken, and because the inter-beam distance is known, they act as a scale for image analysis programs like ImageJ. Traditionally, this method has been used to measure larger morphological traits (e.g., limb length, crown-rump length) to serve as proxies for overall body size, whereas applications to smaller anatomical features remain limited. To that end, we used PLP to measure the testes of 18 free-living mantled howler monkeys (Alouatta palliata) at La Selva Biological Station, Costa Rica. We tested whether this method could reliably measure this relatively small and globular morphology, and whether it could detect differences among individuals. We tested reliability in three ways: within-photo (coefficient of variation [CV] = 4.7%), between-photo (CV = 5.5%), and interobserver (intraclass correlation = 0.92). We found an average volume of 36.2 cm3 and a range of 16.4-54.4 cm3, indicating variation in testes size between individuals. Furthermore, these sizes are consistent with a previous study that collected measurements by hand, suggesting that PLP is a useful method for making noninvasive measurements of testes.

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The consumption of vertebrate tissues and eggs (hereinafter "meat") is relatively common among some primates that are highly frugivorous or eclectic omnivores, but rare or absent in those that are highly folivorous. The Neotropical howler monkeys (Alouatta spp.) belong in the latter group. Here we report the consumption of meat by free-ranging urban black and gold howler monkeys (Alouatta caraya) and discuss the potential role of the consumed meat as a source of energy, protein, or micronutrients. We studied three groups of howler monkeys (comprising four to seven individuals), living in city squares (0.6, 1.5, and 1.9 ha) in south Brazil, from July 2022 to May 2023 (65 days; 797 h of observations). All of the study groups were spontaneously supplemented daily by people with variable amounts and types of food provided. Meat was only offered in the two larger squares. The groups' diets included leaves (42-49% scan sampling feeding records), fruit (3-20%), and flowers (2-5%) from 13 to 20 plant species, and considerable amounts of supplemented food (27-50%). We recorded 33 individual events of ingestion of supplemented cooked meat, three individual events of dove egg predation, and three bird nest inspections without egg consumption. All members of the two groups in the larger squares, except an infant male, ingested meat at least once. Meat accounted for 1% of total scan feeding records of both groups with access to this supplement. We conclude that whereas the opportunistic consumption of meat probably contributed only minor amounts of energy and protein to the study subjects, it may have benefitted them with micronutrients that are scarce in plant foods.

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Non-lethal impacts of dogs on primates have seldom been assessed. We used an experimental approach to determine if mantled howler monkeys (Alouatta palliata) perceive dog barks as an aversive stimulus and thus display physiological and behavioral responses toward simulated barks. For one year (1754 h of observations) we studied 16 adult males belonging to five groups in Los Tuxtlas (Mexico), and recorded the occurrence of naturally occurring dog barks, their sound pressure level (SPL), and the behavioral responses of howler monkeys to barks. We then exposed males to bark playbacks at two SPL treatments, 40 and 80 dB in a total of 50 experiments. We assayed glucocorticoid metabolite concentrations in fecal samples (fGCM) as a marker of the physiological stress response of males. We also recorded the duration of vigilance, vocalizations, and flight in relation to playbacks. Naturally occurring barks were frequent and usually elicited behavioral responses by males. fGCM concentrations increased after bark playbacks and with stimuli intensity. Time spent vigilant increased following playbacks independently of stimuli intensity but both vocalizations and flight were linked to stimuli intensity: vocalizations were the longest after barks played-back at 80 dB, but males spent more time fleeing in response to 40 dB bark playbacks. These results provide evidence that dog barks are pervasive in the habitat of mantled howler monkeys living at Los Tuxtlas and disturb males, both physiologically and behaviorally. Although the potential costs of physiological and behavioral responses could not be determined, there is sufficient evidence to assume that they do have negative impacts on individuals. Therefore, our study provides avenues for future research on dog-wildlife interactions and valuable information for the design of conservation actions aimed at mitigating the impact of dogs on mantled howler monkeys.

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Historically, Mexico has had an important role in primate conservation research, however, studies have rarely included the human dimensions of primatology. Inclusion of these disciplines should be a priority, considering that human activities are responsible for the current socio-ecological crisis. Mexico is habitat for three primate species, and all are threatened. This urgency demands new approaches and broader perspectives. First, we propose three main research frameworks relevant for conducting PCEPs in Latin America: Participatory Action Research, Arts-based education in PCEPs and Knowledge Coproduction. Furthermore, we aimed to (1) describe a case study about primate conservation education in Southern Mexico based on participatory visual methods under the umbrella of Participatory Action Research (PAR), and (2) to conduct a self-reflective, critical, straightforward, and constructive analysis of the experience. We discuss the various challenges faced during the process (e.g., traditional teaching prevalence at schools, teachers that are not school-based, time and academic constraints). Additionally, we highlight some PAR aspects applicable for researchers and practitioners interested to go further than knowledge transmission (e.g., codesign, arts-based education, placed-based education, critical thinking, and capacity building). To collectively progress in primate conservation education in Mexico and other Latin American countries, projects could greatly benefit from context-specific, people-centered approaches, such as PAR. We encourage researchers to share more of their personal research experiences including both their successes and failures.

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Most primate taxa are threatened by extinction and their populations are decreasing. The persistence of primates is thus conditional on conservation actions aimed at protecting them and their habitat. Here, we focus on the conservation of mantled howler monkeys (Alouatta palliata) in the Los Tuxtlas Biosphere Reserve, Mexico. Following the creation of the reserve in 1998, habitat availability and howler monkey abundance increased, suggesting that progress was being made in terms of the conservation of this species. Recent events, however, suggest otherwise, as mantled howler monkey habitat within the biosphere reserve is being disturbed by mining operations endorsed by the Mexican government. We report this case to raise awareness about the challenges for primate and habitat conservation in protected areas.

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Howler monkeys (genus Alouatta) exhibit the most extensive distribution among platyrrhines, comprising Mesoamerican and South American species groups, with the South American group including the Brazilian endemic A. belzebul species complex encompassing A. belzebul, A. discolor, and A. ululata. We herein analyzed their phylogenetic relationship, nucleotide and haplotype diversity, and population demography based on the mitochondrial gene cytochrome b. The phylogenetic and median-joining network analyses distinguished A. discolor, distributed in the west bank of the Xingu River, from A. belzebul on the east bank. This river is a zoogeographic barrier for these species. We did not find evidence of phylogenetic structure between the A. belzebul populations of opposite banks of the Tocantins River, likely related to the changes in the position of this river to the northeast in the late Pleistocene. The A. belzebul along this river showed great morphologic and haplotype diversity, and A. belzebul from the Amazon have kept a larger population size than A. discolor. We herein describe the karyotype of A. discolor, which was similar to those described for A. ululata and A. belzebul. Our results showed two well-defined and supported clades for A. discolor and A. belzebul. However, a new assessment of A. ululata across a large distribution of sampling is required due to the lack of a clear phylogenetic structure.

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For wild primates, demography studies are increasingly recognized as necessary for assessing the viability of vulnerable populations experiencing rapid environmental change. In particular, anthropogenic changes such as habitat loss and fragmentation can cause ecological and behavioral changes in small, isolated populations, which may, over time, alter population density and demographic structure (age/sex classes and group composition) in fragment populations relative to continuous forest populations. We compared our study population of Endangered black howler monkeys (Alouatta pigra) in 34 forest fragments around Palenque National Park (PNP), Mexico (62 groups, 407 individuals), to the adjacent population in PNP, protected primary forest (21 groups, 134 individuals), and to previous research on black howlers in fragments in our study area (18 groups, 115 individuals). We used χ2 and Mann-Whitney U tests to address the questions: (a) what is the current black howler demographic population structure in unprotected forest fragments around PNP? (b) How does it compare to PNP's stable, continuous population? (c) How has it changed over time? Compared to the PNP population, the fragment populations showed higher density, a significantly lower proportion of multimale groups, and significantly fewer adult males per group. The population's age/sex structure in the fragmented landscape has been stable over the last 17 years, but differed in a higher proportion of multifemale groups, higher density, and higher patch occupancy in the present. In the context of conservation, some of our results may be positive as they indicate possible population growth over time. However, long-term scarcity of adult males in fragments and associated effects on population demographic structure might be cause for concern, in that it may affect gene flow and genetic diversity. The scarcity of adult males might stem from males experiencing increased mortality while dispersing in the fragmented landscape, whereas females might be becoming more philopatric in fragments.

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BACKGROUND: In 2007-2009, a major yellow fever virus (YFV) outbreak in Northern Argentina decimated the local howler monkey (Alouatta) population. AIMS: To evaluate whether the surviving howler monkeys possess advantageous genetic variants inherited from monkeys alive prior to the YFV outbreak, we explored the relationship between Toll-like receptor (TLR) 7 and TLR8 gene variation and YFV susceptibility. METHODS: We used samples from Alouatta individuals in Misiones, Argentina alive before the YFV outbreak, individuals that died during the outbreak, and individuals that survived the outbreak and are alive today. We measured genetic divergence between Alouatta YFV exposure groups and evaluated Alouatta-specific substitutions for functional consequences. RESULTS: We did not find different allele frequencies in the post-YFV exposure Alouatta group compared to the pre-exposure group. We identified three nonsynonymous variants in TLR7 in Alouatta guariba clamitans. Two of these substitutions are under positive selection in functionally important regions of the gene. DISCUSSION AND CONCLUSIONS: Our results did not indicate that surviving howler monkey spossess advantageous genetic variants at greater frequency than those alive before the YFV outbreak. However, the positively selected unique coding differences in A. guariba clamitans are in the region important in pathogen detection which may affect YFV resistance. Morework is necessary to fully explore this hypothesis.

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Bertiella sp., a cestode known to infect a variety of hosts, including nonhuman primates and humans, was identified in Paraguay as early as 1895, but no systematic analysis of wild primates' gastrointestinal parasites has ever been carried out in Paraguay. Increased urbanization in southwest Paraguay has pushed the Paraguayan howler monkey (Alouatta caraya) into anthropogenic habitats, particularly in the city of Pilar (Ñeembucú department), giving rise to greater potential for zoonotic transmission between wild primates and humans. From July to December 2018, fecal samples were noninvasively collected from 48 howlers inside Pilar (urban environment), the Pilar Military Base (intermediate environment), and a ranch 27 km outside Pilar in the humid Chaco (natural environment) and analyzed for Bertiella eggs and proglottids using macro-analysis and formol-ether sedimentation. Howlers living in the urban environment had the highest rates of Bertiella infection (50% prevalence), with considerably lower infection rates in the intermediate environment (6.25% prevalence) and natural habitats (0% prevalence). A χ2 goodness-of-fit test indicated a significant difference between the three habitat types (p = .007, χ2 = 10.005, df = 2). While the habitat seems to impact the frequency of infection, Bertiella was not observed to select for other factors such as age or sex of the primate host. Here we identified a significant increase in the frequency of Bertiella infection in an urban environment, which can then be further transmitted to new hosts with more direct primate contact. Bertiella infection has already been documented in humans in Paraguay, all of which were associated with close primate contact. As howlers move into more urban habitats due to urbanization and habitat fragmentation, Bertiella could be introduced into this new ecosystem and has the potential to cause further infections in humans.

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Deforestation is widely recognised as an agent of human disturbance that causes widespread destruction of species habitats and can result in animals occupying forest patches with limited food resources. When animals are forced to change habitats, they must also adjust their diet, activity budgets and social behaviour in response to facing new ecological and environmental conditions. Only a few studies have analysed the influence of habitat conditions on social interactions of immature howler monkeys. In this study, we examined the effects of variation in food availability on social interactions of young howler monkeys (Alouatta palliata mexicana). This was accomplished by observing infant and juvenile members of two groups inhabiting a continuous forest habitat (640 ha) and three groups living in different-sized forest fragments (4, 42 and 93 ha) for a 15-month non-consecutive period. We quantified the Potential Food Availability Index (PFAI) for each habitat type based on the basal area, the Shannon-Wiener diversity index and abundance of food tree species. We used 15-min focal animal sampling to record the occurrence and/or duration of affiliative and agonistic behaviours. In habitats with higher PFAI, we observed more social play and proximity in infants aged 4-7 months, grooming in infants aged 8-14 months and social play in juveniles. Conversely, juveniles' grooming rates and 0- to 3-month-old infants' proximity rates decreased as PFAI increased. Our results suggest that food resource variation influences young howler monkeys' social interactions. The reduction in social interactions due to low food availability may represent an energy-saving strategy to cope with limited resources in habitats disturbed by anthropogenic activities.

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While howlers are the most ecologically flexible of the atelines, they must still respond to issues arising from anthropogenic modifications, such as fragmentation or dietary changes. A group of Alouatta palliata living in a highly modified landscape (commensal group) at the Curú Wildlife Refuge in Costa Rica was compared to howlers with limited human influence (control group). The commensal group had a more frugivorous diet than the control group (H = 9.23, p = 0.002) due to crop-foraging of mango fruits. The commensal group maintained a larger home range than the control group, at 39 and 10 ha, respectively. The commensal group also had increased travel (H = 7.37, p = 0.007) and feeding (H = 7.34, p = 0.007) time, as well as reduced proximity to conspecifics (H = 44.77, p = 0.000). There were no significant differences in rates of either aggressive or affiliative social behaviours. The increased home range, shift in diet, increased travel and foraging time and reduced group cohesion demonstrated by these animals represent responses to the varied utility of available landscapes and the more widely dispersed resources in their range. These data contribute to our understanding of Alouatta, one of the most successful of Neotropical primates in modified landscapes.

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Mycoplasma spp. and Bartonella spp. are Gram-negative bacteria transmitted by arthropod vectors that infect red blood cells of several mammal species. This study investigated the occurrence and genetic diversity of hemoplasmas and Bartonella spp. in 68 howler monkeys kept in captivity in São Paulo, a southeastern state in Brazil. In addition, possible hematological, biochemical and electrophoretic changes of serum proteins associated with the occurrence of hemoplasmas and Bartonella spp. in captive primates were also investigated. The cPCR results showed that all sampled howler monkeys were negative for Bartonella spp. based on the gltA gene. The cPCR results indicated that 18 (26.47%) non-human primates (NHP) were positive for hemoplasmas based on the 16S rRNA gene. Monocyte and lymphocyte counts were higher in hemoplasma-positive howlers (P < 0.05). Platelet counts decreased in nonhuman primates (NHP) positive for hemoplasmas (P < 0.05). The results from the blood serum proteinogram and biochemistry analyses were not significantly different between NHPs positive and negative for hemotrophic mycoplasmas. Phylogenetic analysis using Bayesian Inference (BI) based on the 16S rRNA gene positioned the obtained sequences close to 'Candidatus Mycoplasma kahanei'. The analysis of sequence diversity of the 16S rRNA gene showed that 5 different genotypes are circulating in NHP in Brazil and in the world; besides, a clear separation between the sequences of hemoplasmas that infect NHP of the Sapajus and Alouatta genus in Brazil was found, probably corresponding to two different species. The pathogenic potential of this hemoplasma species in NHP should be further investigated.

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Multiple species of Phlebotominae are vectors of Leishmania (Protozoa: Trypanosomatidae), which causes visceral leishmaniasis (VL) and cutaneous leishmaniasis (CL). To describe the Phlebotominae (Diptera: Psychodidae) related to the environments of black and gold howler monkeys Alouatta caraya (Humbodlt, 1812) (Primates: Atelidae), potential vectors were sampled in different landscapes and vertical strata of sleeping trees. Phlebotomine captured between December 2011 and March 2012 (2365 individuals) belonged to eight species, of which Nyssomyia neivai (Pinto, 1926) (61.4%) and Migonemyia migonei (França, 1920) (18.73%) were the most abundant, and Ny. withmani was recorded for the first time in the Chaco province. In the 'peri-domestic' landscape, the phlebotomine were mainly captured in henhouses (78.7%), whereas the tree canopy in 'rural' and 'wild' landscapes yielded 31.2% and 29.1% of the phlebotomine, respectively. A significant association between the type of landscape and the species of phlebotomine was observed by multivariate analysis. Lutzomyia longipalpis (Lutz & Neiva, 1912) and Mg. migonei were associated with 'peri-domestic' landscape, and Ny. neivai was associated with the 'wild' landscape. The results of this prospective study suggest that the interaction between phlebotomine and A. caraya could be a key factor with respect to understanding the epidemiology of leishmaniasis.

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BACKGROUND: This study aimed at assessing the heart function of one neotropical primate (Alouatta guariba clamitans) kept in captivity using radiography, electrocardiogram (ECG) and Doppler echocardiography. METHODS: Ten adult healthy howler monkeys (A. g. clamitans) were evaluated under general anaesthesia. Vertebral Heart Scores (VHS) were obtained from radiographic studies. Ejection fraction, shortening fraction of left ventricle, left atrial/aortic root ratio, ascending aortic diameter, peak velocity of pulmonary, mitral, tricuspid and aortic blood flow and other values were measured by Doppler echocardiography. Heart rate, mean electrical axis of QRS complex, P, Q, R, S, T amplitude, P, PR interval, QRS, QT interval duration and ST segment unbalancing were measured by ECG. RESULTS AND CONCLUSIONS: Exam techniques were akin the ones used in humans. Doppler echocardiographic, radiographic, electrocardiographic and clinical parameters for howler monkey were described and correlated. The results have shown profiles of cardiovascular function and structure of A. g. clamitans.

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BACKGROUND: Analyses of environmental correlates of the composition of gastrointestinal parasite communities in black howler monkeys (Alouatta pigra) have been hindered by inadequate calibration techniques of detection and quantification methods of the parasites. Here we calibrate samples and compare the likelihood of parasite detection using two flotation techniques, FLOTAC and Mini-FLOTAC, and compare flotation solution, preservation method and dilution ratio for egg detection and counts of the most common parasites (Controrchis spp. and Trypanoxyuris spp.) in howler monkeys. RESULTS: For samples preserved in 5% formalin, the Mini-FLOTAC technique was the best option for qualitative and quantitative copro-microscopic analysis. This technique displays an 83.3% and 100% detection of Controrchis spp. and Trypanoxyuris spp. infections, respectively. For the trematode Controrchis spp., more eggs per gram of feces (EPG) were recorded with the flotation solution (FS) #7 (zinc sulfate; specific gravity SG = 1.35) at 1:20 and 1:25 dilution than other methods. By contrast, for the nematode Trypanoxyuris spp., the best results were recorded with FS1 (sucrose and formaldehyde; SG = 1.20) at 1:10 dilution. CONCLUSIONS: We recommend the Mini-FLOTAC technique for general use with parasite analysis on frugivore/folivores like the howler monkey, especially if many samples are analyzed. The technique has a high detection rate and the best EPG counts, allowing the qualitative and quantitative analysis of parasite load among the species or populations without the need for specialized equipment.

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Studies on parasites infecting non-human primates are essential to better understand the potential threat to humans of zoonoses transmission, particularly under the current processes of pervasive land use change and biodiversity loss. The natural ecosystems in the Middle Magdalena river basin in Colombia have suffered a dramatic reduction and transformation into pastures and agroindustrial monocultures, threatening their biodiversity, and probably affecting the dynamics between parasites and their hosts, as well as altering the disease transmission cycles between wild populations and humans. This study evaluated seasonality, prevalence and richness of intestinal parasites in three species of neotropical primates: Cebus versicolor, Ateles hybridus and Alouatta seniculus, in a fragmented forest in the Middle Magdalena river valley, Colombia. One hundred and eighty five faecal samples were collected between 2010 and 2015. Direct faecal smears were performed with saline solution (0.85%) and iodine solution (1%), in order to identify larvae and eggs based on their morphology. A large proportion of the samples examined (72.9%) was positive for intestinal parasites; seven families of nematodes were identified: Trichuridae, Trichostrongylidae, Oxyuridae, Strongyloididae, Ancylostomatidae, Ascarididae and Gnathostomatidae, two of protozoans: Entamoebidae and Balantiididae, as well as some eggs of trematodes, cestodes and acanthocephalans. Additionally, DNA extraction and sequencing were conducted on 30 faecal samples in order to identify Giardia sp. and Blastocystis hominis, two parasite species also present in humans. Molecular testing for Giardia sp. was negative and Blastocystis hominis was identified in a single sample of Alouatta seniculus. No clear patterns were observed for prevalence of intestinal parasites according to the season; nonetheless, parasite species richness was higher during the dry season. This study builds on our current understanding of intestinal parasites infecting wild neotropical primates and provides novel information on the patterns of intestinal parasites in primate communities exposed to anthropogenic disturbance.

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The objective of this study was to identify intestinal protozoa in fecal samples of illegally commercialized New World nonhuman primates apprehended by governmental authorities and sent to a Wildlife Screening Center in the municipality of Seropédica, State of Rio de Janeiro, under the administration of Instituto Brasileiro de Meio Ambiente e Recursos Naturais. Feces from marmosets (crossbreeding among Callithrix jacchus and C. penicillata) and brown howler monkeys (Alouatta fusca) were collected and submitted to Richties formaldehyde-ether sedimentation technique. Smears were made with the sediment and submitted to safranin-methylene blue and Wheatleys modified trichrome stainings. Phenol-auramine staining was used in order to compare positive smears for Cryptosporidiumoocysts stained with safranin-methylene blue technique. Three (100%)fecal samples of brown howler monkeys and eight of common marmosets (88.9%) were positive for Cryptosporidium oocysts.Blastocystis hominis-like forms were observed in all samples of brownhowler monkeys and in 66.7% (6/9) of marmosets. New World nonhuman primates Callithrix crossbreed species and A. fusca can harbor forms similarly identified as potential zoonotic organisms.The strict contact between monkeys and humans can represent risks for both by mutual transmission of pathogens. It is unknown if monkey species studied in the present work are either infected with these parasites in natural environment or acquire it when submitted to human contact. Stressing is also a factor that deserves attention on animals submitted to capture, apprehension and transport to Wildlife Screening Centers.(AU)

O objetivo deste estudo foi identificar protozoários intestinais em amostras fecais de primatas neotropicais não-humanos, comercializados ilegalmente, apreendidos por autoridades governamentais, e enviados para um centro de triagem de animais silvestres no município de Seropédica, Estado do Rio de Janeiro, sob a administração do Instituto Brasileiro de Meio Ambiente e Recursos Naturais. Fezes de micos-saguí (cruzamento entre Callithrix jacchus e C. penicillata) e bugios marrons (Alouatta fusca) foram coletados e submetidos à técnica de centrifugo-sedimentação de Ritchie. Esfregaços foram confeccionados com o sedimento e submetidos à coloração pelas técnicas da safranina-azul de metileno e Tricrômio modificada de Wheatley. Três (100%) amostras fecais de bugios marrons e oito (88,9%) de micos-saguí foram positivos para oocistos de Cryptosporidium. Formas de Blastocystis homonis-simile foram observadas em todas as amostras de bugios marrons e em 66,7% (6/9) de micos-saguí. Primatas neotropicais não-humanos como os micos-saguí originados do cruzamento de espécies de Callithrix e a espécie A. fusca podem abrigar formas similarmente identificadas como organismos com potencial zoonótico. O contato estrito entre macacos e humano pode representar riscos para ambos por transmissão mútua de patógenos. Não está esclarecida se as espécies de macacos estudadas no presente trabalho são também infectadas com estes parasitos em ambiente natural ou adquirem estes quando submetidos ao contato humano. Estresse é também um fator que merece atenção para os animais submetidos à captura, apreensão e transporte para o centro de triagem de animais silvestres.(AU)

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A long-term study was carried out on a black howler monkey (Alouatta caraya) population living in 150 ha of forest patches spread out in a 3,000 ha rural area in Northern Argentina. A total of 22 different groups were located between 1980 and 1984 and 11 of these were monitored regularly during 28 months. Ecological density varied between 12.14 and 12.93 groups per sq km of thall dense forest (0.80 to 1.15 ind./ha; biomass 306 to 365 kg/sq km). Solitaries and small associations of adult or subadult individuals of both sexes were also recorded but occupied habitats of inferior quality. Mean sizes of reproductive groups varied from 6.4 to 8.4 and the range was 3 to 15 individuals. Reproductive groups had 1 to 3 adult males, 1 to 3 adult females, and several immatures. Sex ratio was biased toward females among the adults but it varied in other age classes. Births occurred throughout the year showing a peak in the colder and drier season. Subadult or young adult males and females dispersed from suspected natal groups and became solitaries or joined associations. Males invaded groups and displaced or coexisted with resident males. Infanticides and disappearances of infants were associated with male changes. Comparative censuses on an island not far from the main study area showed higher density and biomass (2.8 ind./ha; 1,117 kg/sq km) and different group sizes and composition. Habitat features as well as the history of each study site may account for the observed demographic differences.