Lead exposure and its relationship with fecal cortisol levels in black howler monkeys (Alouatta pigra)

Efficiently detecting early environmental threats to wildlife is vital for conservation. Beyond obvious dangers like habitat loss or deforestation, our study focuses on one of the most hazardous toxic metals for wildlife: lead (Pb). Pb is a widespread, cumulative, and insidious environmental pollutant that can trigger a wide range of physiological, biochemical, and behavioral disorders. In fact, Pb can cause permanent dysfunction of the major stress system, the hypothalamic pituitary adrenal (HPA) axis. We analyzed Pb and cortisol concentrations in fecal samples from Alouatta pigra in southern Mexico. Fecal samples were collected across six sites categorized as free-ranging (n = 65; conserved and disturbed) and from captive animals (n = 58). Additionally, we collected soil samples (n = 35). We found that Pb was present in 28% of fecal samples and 83% of soil samples. There was a positive relation between fecal and soil Pb levels, and fecal Pb concentration was negatively associated with cortisol levels. However, the claim of Pb being a direct interference with HPA axis requires further investigation. Given our findings, assessing wildlife exposure can be a valuable tool for understanding potential Pb exposure levels in the environment and its possible implications for human health. It can also serve as an early warning system of these consequences.

Estimating the impact of the illegal trade of primates in Mexico: a potential threat to wildlife

The primates of Mexico, Ateles geoffroyi, Alouatta palliata, and Alouatta pigra, are seriously threatened by habitat loss, fragmentation, and illegal hunting and trade. Very little is known about the extent of illegal trade and its impacts on declining primate populations. Our study proposes a potential method based on estimating the number of individuals that die in the trade before being detected and those that probably cannot be detected. This facilitates estimating the number of animals extracted and allows an assessment of how trafficking impacts their populations. We derive estimates from seizure data of primates in Mexico between 2010 and 2019. To do this, we created wildlife detection rates and mortality rates from the existing literature (scientific articles, journalistic articles, and notes) to estimate the number of primates that die during capture, transport, and sale and the number of trafficked primates that were not detected by Mexican authorities. We estimate that 946 primates were removed from the wild for the pet trade each year (spider monkey Ateles geoffroyi = 854; black howler monkeys Alouatta pigra = 38, mantled howler monkey Alouatta palliata = 54). The annual reduction in population size caused by trafficking was greatest for Ateles geoffroyi (2.2%), followed by Alouatta pigra (1.3%), and Alouatta palliata (0.4%). Our estimates show the percentage of impacts that trafficking has on Mexican primate populations. Nevertheless, trade has the potential to impact declining populations and still must be addressed.

Social media’s potential to promote conservation at the local level: an assessment in eleven primate range countries

Historically, Internet access has been linked to a country’s wealth. However, starting a decade ago, this situation changed dramatically and Internet access became increasingly available in primate range countries. The rapid growth of smartphone use in developing nations has created new avenues to communicate conservation. Here we assess the potential of social media to promote primate conservation at the local level within primate range countries. We interviewed 381 people in communities associated with 18 conservation projects from 11 countries to assess their use of social media. We found that 91% of the people had at least one social media account and 95% of these people checked their accounts daily. The median number of contacts per person across all platforms was 453 and 300 considering only each person’s most used platform. We also documented that local conservation projects had a diversity of information they wanted to relay to the local community through social media. Our research highlights the potential for social media to be an extremely useful communication tool for tropical conservation scientists. Thus, we encourage more conservation groups to explore using social media to communicate to local communities and to report on the impact it has on conservation.

Anomalous pigmentation in American primates: review and first record of a leucistic black howler monkey in southeast Mexico

Leucism is an aberration of color that occurs in individuals as a consequence of genetic mutations. Along with albinism and piebaldism, leucism is one of the most commonly reported types of chromatic anomalies in mammals, however, detailed descriptions of such conditions are rare. We report the first record of a leucistic black howler monkey (Alouatta pigra) in southern Mexico, an apparently healthy individual who was the male of a typical black howler group. Additionally, we compiled records of anomalous pigmentation in American primates published in peer-reviewed journals between 1960 and 2021, as well as social media posts regarding casual observations of individuals with such conditions. We found 11 scientific articles which described 13 records of anomalous pigmentation in a total of 44 individuals, from five species, three subspecies and one hybrid. Leucism was the most widely reported condition with six records. We discovered 19 online posts of 20 individuals with anomalous pigmentation, which included two species not reported in scientific literature. Our results suggest that anomalous coloration is not a significant threat to survival, but its occurrence raises interesting, and possibly alarming, questions about the causes of such conditions. We encourage researchers and civil society to formally report such observations of animals with color aberrations, to expand upon the understanding of this phenomenon and to get involved in the conservation of tropical forests.

The Primate Cultural Significance Index: applications with Popoluca Indigenous people at Los Tuxtlas Biosphere Reserve

BACKGROUND

The study of the cultural significance (CS) of biodiversity provides key information to develop conservation strategies consistent with traditions and perceptions of human communities. In Los Tuxtlas Biosphere Reserve (TBR) in Mexico, the mantled howler monkeys (Alouatta palliata mexicana) and the black-handed spider monkeys (Ateles geoffroyi vellerosus) have historically coexisted with Popoluca Indigenous Peoples. This study sought to determine how the presence of a natural protected area (TBR location) and a range of sociodemographic factors (gender, age, origin, language proficiency, education level, religion) relate to the CS held by the Popoluca Indigenous People in relation to these two endangered primate species.

METHODS

The first Primate Cultural Significance Index (PCSI) was designed as a composed index of 11 cultural variables (sub-indices) and was applied randomly to a representative size sample of people over 15 years old in two Popolucas communities, one within the TBR (Piedra Labrada = 81 people) and another outside (Los Mangos = 91). U Mann-Whitney tests were used to compare the PCSI between communities and Generalized Linear Models (GLM) to evaluate the sociodemographic factors of participants that influenced the sub-indices in the PCSI.

RESULTS

The cultural significance of spider monkeys held by the Popolucas was higher for the community within the TBR than for the community outside, while for howler monkeys it was higher outside. For both primate species across the two communities, the most relevant sub-indices were (1) interest in conservation and (2) touristic significance of primates. Sociodemographic factors of participants influenced nine sub-indices of cultural significance out of the possible 10 sub-indices applied for each primate species. The demographic factors that most influenced each sub-index for both species were location and gender.

CONCLUSIONS

The main differences found between communities may be linked to the conservation and sustainable development programs promoted by the reserve, as well as the greater persistence of Popolucan ancestral traditions within the boundaries of the reserve. We recommend that conservation efforts should focus on people less interested about primate conservation (women, non-natives and residents outside the reserve), and turn to the leadership of people more interested (native men who reside inside the reserve).

Salivary proteome of a Neotropical primate: potential roles in host defense and oral food perception

BACKGROUND

Saliva contains a very complex mixture of proteins for defense against microbiological pathogens and for oral food perception. Howler monkeys are Neotropical primates that can consume a mostly leaf diet. They are well known to thrive in highly disturbed habitats where they may cope with a diversity of dietary challenges and infection risks. We aimed to describe the salivary proteome of howlers to contribute to better understanding of their physiology.

METHODS

We analyzed the salivary proteins of wild black howler monkeys (Alouatta pigra), by SDS-PAGE-1-D and Nano LC-MS/MS and categorized them by their function involved in host defense and oral food perception.

RESULTS

Our proteomic analysis identified 156 proteins in howler saliva including a number of host defense peptides that are the first line of defense in mammals, such as defensin, cathelicidin, dermcidin, and lactotransferrin, and proteins with anti-bacterial, anti-fungal, and anti-viral capacity, such as IgA, IgG, IgM, BPI, salivary heat shock 70 kDa protein, beta-2-microbulin, and protein S-100. We also identified key proteins necessary for taste perception, including salivary carbonic anhydrase VI, cystatin D, IgA, and fatty acid-binding protein. Proteins to detect astringent foods were identifying, including four members of cystatins (A, B, C and D), lactoperoxidase, and histidine-rich proteins. No chitinase and amylase were identified as would be expected because howlers do not eat insects and little starch. These findings provide basic information to future studies in oral biology, ingestive physiology, and physiological ecology of mammals and non-human primates.

Evidence-based conservation education in Mexican communities: Connecting arts and science

Several studies suggest that 63% of primate species are currently threatened due to deforestation, pet-trade, and bushmeat hunting. Successful primate conservation strategies require effective educational programs capable of enhancing critical system-thinking and responsible behavior towards these species. Arts-based conservation education can simultaneously foster cognitive and emotional processes. In this paper, we evaluate an arts-based educational program focused on the conservation of black howler monkeys (Alouatta pigra). Our goals were to determine (1) whether children’s knowledge changed with our educational techniques, (2) if there was a particular educational technique that better improved the children’s learning, and (3) the children’s emotional feedback regarding the whole program. A total of 229 children from communities located in primate-habitat areas, both inside and outside protected areas, participated in the study. Different educational techniques were tested (storytelling, theater and shadow puppets), contrasted with a control group, and evaluated through an analysis of drawings. Our results showed that children’s knowledge increase with each art-based technique, with storytelling being the most effective for children’s learning. Specific drawings indicators also revealed the increase of children’s knowledge and a decrease of misconceptions between pre and post evaluations. Finally, a satisfaction survey about the program showed a high positive feedback. The study highlights the value of designing multidisciplinary projects, where arts-based education program (grounded in scientific information) has shown to be a successful way to communicate animal knowledge and promote conservation.

Games academics play and their consequences: how authorship, h-index and journal impact factors are shaping the future of academia

Research is a highly competitive profession where evaluation plays a central role; journals are ranked and individuals are evaluated based on their publication number, the number of times they are cited and their h-index. Yet such evaluations are often done in inappropriate ways that are damaging to individual careers, particularly for young scholars, and to the profession. Furthermore, as with all indices, people can play games to better their scores. This has resulted in the incentive structure of science increasingly mimicking economic principles, but rather than a monetary gain, the incentive is a higher score. To ensure a diversity of cultural perspectives and individual experiences, we gathered a team of academics in the fields of ecology and evolution from around the world and at different career stages. We first examine how authorship, h-index of individuals and journal impact factors are being used and abused. Second, we speculate on the consequences of the continued use of these metrics with the hope of sparking discussions that will help our fields move in a positive direction. We would like to see changes in the incentive systems, rewarding quality research and guaranteeing transparency. Senior faculty should establish the ethical standards, mentoring practices and institutional evaluation criteria to create the needed changes.

Molecular detection of Bifidobacterium spp. in faeces of black howler monkeys (Alouatta pigra)

BACKGROUND

Bifidobacterium genus are considered to be beneficial bacteria for their hosts; however, knowledge about the specific species that are part of the gut microbiome of howler monkeys is scarce. Polymerase chain reaction (PCR) is a useful technique for the identification of non-cultivable or difficult to grow bacterial species. With the goal of detecting species of the genus Bifidobacterium in black howler monkeys, we used PCR on DNA derived from faecal samples.

METHODS

We collected and extracted DNA from 40 faecal samples. Using specific primers, we performed PCR and nested PCR to detect members of the Bifidobacterium genus and a subset of species: Bifidobacterium adolescentis, Bifidobacterium bifidum, Bifidobacterium infantis, Bifidobacterium longum and Bifidobacterium animalis subsp. animalis.

RESULTS

97.5% (39/40) of the samples were positive for Bifidobacterium spp. We found B longum in 100% of the analysed samples.

CONCLUSIONS

This is the first report of B longum in black howler monkey faeces.

Salivary tannin-binding proteins are a pervasive strategy used by the folivorous/frugivorous black howler monkey

Dietary tannins can affect protein digestion and absorption, be toxic, and influence food selection by being astringent and bitter tasting. Animals that usually ingest tannins may regularly secrete tannin-binding salivary proteins (TBSPs) to counteract the negative effects of tannins or TBSPs production can be induced by a tannin-rich diet. In the wild, many primates regularly eat a diet that contains tannin-rich leaves and unripe fruit and it has been speculated that they have the physiological ability to cope with dietary tannins; however, details of their strategy remains unclear. Our research details the salivary protein composition of wild and zoo-living black howler monkeys (Alouatta pigra) feeding on natural versus manufactured low-tannin diets, and examines differences in TBSPs, mainly proline-rich proteins (PRPs), to determine whether production of these proteins is dependent on the tannin content of their food. We measured the pH, flow rate, and concentration of total protein and trichloroacetic acid soluble proteins (an index of PRPs) in saliva. Howler monkeys produced slightly alkaline saliva that may aid in the binding interaction between tannin and salivary proteins. We used gel electrophoresis to describe the salivary protein profile and this analysis along with a tannin-binding assay allowed us to detect several TBSPs in all individuals. We found no differences in the characteristics of saliva between wild and zoo-living monkeys. Our results suggest that black howler monkeys always secrete TBSPs even when fed on foods low in tannins. This strategy of constantly using this salivary anti-tannin defense enables them to obtain nutrients from plants that sometimes contain high levels of tannins and may help immediately to overcome the astringent sensation of their food allowing howler monkeys to eat tanniferous plants.

Flotation techniques (FLOTAC and mini-FLOTAC) for detecting gastrointestinal parasites in howler monkeys

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.

Electronic supplementary material

The online version of this article (10.1186/s13071-017-2532-7) contains supplementary material, which is available to authorized users.

Highly nested diets in intrapopulation monkey-resource food webs

Recently several studies have focused on the structure of ecological networks to provide insights into ecological and coevolutionary dynamics of interacting species. However, rarely have the tools of ecological networks been used to understand how feeding relationships vary among individuals of the same population. Here we use 7 years of data and network analyzed to examine the intrapopulation diet variation in a group of howler monkeys (Alouatta palliata). We show that individual monkey-resource food webs are nested, but not modular and the stability of these patterns is independent of time of day or season. Our findings indicated that individuals do not forage randomly when compared to null models and that the diets of more selective monkeys represent subsets of the diets of other individuals. Moreover, there are no subgroups that eat a particular set of available plant species more frequently than other sets, suggesting that the spatial strategy of group foraging plays an important role in the feeding ecology of each group given that individuals of the same group tend to share similar resources while the group remains at a feeding site. Since the diets of more selective individuals are a subset of other monkeys, we suggest that more selective monkeys are able to outcompete others for preferred foods. Additionally, we did not observe differences in nutritional content or spatial abundance of more frequently eaten plant species when compared with less frequently eaten species, but in most cases, the more frequently eaten plant species were Ficus (Moraceae). This reinforces the important role that Ficus trees play in howler monkey feeding ecology, likely due to its year-round availability.

Behavioral and physiological responses to subgroup size and number of people in howler monkeys inhabiting a forest fragment used for nature-based tourism

Animals' responses to potentially threatening factors can provide important information for their conservation. Group size and human presence are potentially threatening factors to primates inhabiting small reserves used for recreation. We tested these hypotheses by evaluating behavioral and physiological responses in two groups of mantled howler monkeys (Alouatta palliata mexicana) at the "Centro Ecológico y Recreativo El Zapotal", a recreational forest reserve and zoo located in the Mexican state of Chiapas. Both groups presented fission-fusion dynamics, splitting into foraging subgroups which varied in size among, but not within days. Neither subgroup size nor number of people had an effect on fecal cortisol. Out of 16 behavioral response variables tested, the studied factors had effects on six: four were affected by subgroup size and two were affected by number of people. With increasing subgroup size, monkeys increased daily path lengths, rested less, increased foraging effort, and used more plant individuals for feeding. As the number of people increased, monkeys spent more time in lower-quality habitat, and less time engaged in social interactions. Although fecal cortisol levels were not affected by the factors studied, one of the monkey groups had almost twice the level of cortisol compared to the other group. The group with higher cortisol levels also spent significantly more time in the lower-quality habitat, compared to the other group. Our results suggest that particular behavioral adjustments might allow howler monkeys at El Zapotal to avoid physiological stress due to subgroup size and number of people. However, the fact that one of the monkey groups is showing increased cortisol levels may be interpreted as a warning sign, indicating that an adjustment threshold is being reached, at least for part of the howler monkey population in this forest fragment.

Potential distribution of Mexican primates: modeling the ecological niche with the maximum entropy algorithm

We developed a potential distribution model for the tropical rain forest species of primates of southern Mexico: the black howler monkey (Alouatta pigra), the mantled howler monkey (Alouatta palliata), and the spider monkey (Ateles geoffroyi). To do so, we applied the maximum entropy algorithm from the ecological niche modeling program MaxEnt. For each species, we used occurrence records from scientific collections, and published and unpublished sources, and we also used the 19 environmental coverage variables related to precipitation and temperature from WorldClim to develop the models. The predicted distribution of A. pigra was strongly associated with the mean temperature of the warmest quarter (23.6%), whereas the potential distributions of A. palliata and A. geoffroyi were strongly associated with precipitation during the coldest quarter (52.2 and 34.3% respectively). The potential distribution of A. geoffroyi is broader than that of the Alouatta spp. The areas with the greatest probability of presence of A. pigra and A. palliata are strongly associated with riparian vegetation, whereas the presence of A. geoffroyi is more strongly associated with the presence of rain forest. Our most significant contribution is the identification of areas with a high probability of the presence of these primate species, which is information that can be applied to planning future studies and then establishing criteria for the creation of areas to primate conservation in Mexico.

Current status of the habitat and population of the black howler monkey (Alouatta pigra) in Balancán, Tabasco, Mexico

We evaluated the habitat and populations of the black howler monkey (Alouatta pigra) in the municipality of Balancán, Tabasco, southeastern Mexico, using a combination of field surveys and remotely sensed data. We identified 21,937 ha of remnant vegetation composed of 1,348 fragments. Fragments separated by up to 200 m were grouped into "clusters" of fragments in accordance with the maximum observed open distance crossed by A. pigra. A total of 11% or 84 of the 772 clusters identified through remote sensing were selected at random, and for these we determined the vegetation type, canopy height, area, and distance to the closest human settlement. In these same 84 clusters, which included a total area of 9,817 ha, from October to June of 2006 we located a total of 1,064 black howler monkeys, including 228 troops and 49 solitary monkeys. A. pigra was found in 62 (74.7%) of all clusters visited, with a cumulative area of 6,032 ha. Troops varied in size from 2 to 15 individuals (average 6.0+/-2.9 ind/troop). Adults were 67% (n=716) of detected individuals, whereas juveniles were 20.5% (n=218) and infants were 12.5% (n=133). We found black howlers to occur at an ecological density of 10.8 ind/km(2), which is low in comparison with A. pigra in other fragmented and conserved sites. We found a statistically significant relationship between the area of clusters and the abundance of howler monkeys (r(2)=0.2, F=10.47, gl=3, P=0.002). In addition, the probability of finding A. pigra was greater in secondary vegetation, riparian vegetation, tropical dry forest, undisturbed tropical oak forest, and palm forest (F=12, gl=3, P<0.0001), as compared with disturbed tropical oak forest. Our results provide data on the distribution, abundance, and population structure of black howler monkeys in a fragmented landscape in the southeast of Mexico. These data are a necessary prerequisite for conservation planning for this species.

Exploring immature-to-mother social distances in Mexican mantled howler monkeys at Los Tuxtlas, Mexico

We analyzed immature-to-mother social distance (juveniles and non-nursing infants) in two Mexican mantled howler monkey (Alouatta palliata) troops inhabiting a tropical rainforest fragment (40 ha) at Los Tuxtlas, Veracruz, Mexico. During July and August of 2000 and 2001 we applied an instantaneous sampling method (317 hr) to record the behaviors of the immatures and their mothers, as well as distances (ordinal scale) between immatures and their mothers (IMD), and between immatures and nonmother individuals (INMD). Immatures were generally less than 5 m away from any individual of the troop. Social distance was influenced by the different behaviors of both mothers and immatures, with the shortest distances occurring during rest (IMD <5 m in 94% of all instantaneous samples) and the longest during exploration (21% > or =10 m) and play (26% > or =10 m). When IMD increased, we found a higher percentage of records <5 m to other individuals, particularly with the probable father. When the variation in distance to the mother and to other individuals in the troop was considered, the immature animals' distance to other troop members depended on the immatures' age and type of behavior. Overall, these results suggest that in this low-activity species the development of the immature is associated with a complex set of relationships with other troop members.

Movement and resource use by a group of Alouatta pigra in a forest fragment in Balancán, México

Uncommonly observed behaviors were systematically recorded in a troop (n = 9 individuals) of black howler monkeys (Alouatta pigra) inhabiting a small forest fragment (1.7 ha) in Leona Vicario, Balancán, Tabasco, Mexico. Between February 2002 and January 2003 (n = 499 h), we observed behaviors such as ground travel (85 occasions, total = 269 min/10.8% of total locomotion time), ground foraging (eight occasions, total = 50 min/0.84% of total feeding time) and drinking water pooled in tree holes (20 times, total = 93 min/0.31% of total activity time). Total time (412 min) for these non-resting behaviors (feeding and locomotion on the ground) is almost equivalent to time devoted to social activities (420 min). These behaviors indicate that howler monkeys may be responding to pressures imposed by the small size of the fragment by adopting diverse strategies to cover their basic nutritional needs in this environment. They accomplish this while exposing themselves to potential predation by coyotes (Canis latrans), as was observed once during the study. It is likely that these behaviors are occurring at an increasing rate among monkeys in fragmented landscapes.

Las Islas de los Changos (the Monkey Islands): the economic impact of ecotourism in the region of Los Tuxtlas, Veracruz, Mexico

This study evaluates the popularity and economic impact of Las Islas de los Changos (the Monkey Islands) as an ecotourism site on Lake Catemaco in the Los Tuxtlas region of Veracruz, Mexico. Two small island colonies of exotic primates, stumptail macaques (Macaca arctoides), have proved to be highly beneficial for the local economy as the main attraction for tourists in this region. From July 1991 to June 1992, data were collected on the number of tourists who took boat trips to visit the primates, and the amount of money spent on tours to the islands. The data suggest that at least 28,470 passengers visit these primate troops annually and spend approximately 88,970 U.S. dollars (USD). Follow-up questionnaires during July 1997 to June 2000 to hotelkeepers and tourist boat operators identified the Monkey Islands as the primary destination for tourists to this region. A comparison of the net income obtained by local ecotourism operators with wages earned through other types of employment in the Los Tuxtlas region, such as working in natural reserves, agriculture, or renting grazing land for cattle, show the relative importance of Las Islas de Los Changos in sustaining the local economy.