Teenagers' perceptions of Mexican primates: A participatory environmental education program for the conservation of mantled howler monkeys (Alouatta palliata) in Los Tuxtlas, Mexico.

This study explores the perceptions that high school students have about mantled howler monkeys in the Mexican community of Balzapote, Veracruz. We systematized the learning process derived from a Primate Conservation Education Program (PCEP) based on participatory action research (PAR) and arts-based education. Our results indicate a decrease in students' fear of monkeys, the recovery of myths and legends about this species, as well as a complex knowledge about monkeys and their habitat.

Bot fly parasitism in mantled howler monkeys (Alouatta palliata): General patterns and climate influences.

Parasitism is a strong selective pressure, and its study is crucial for predicting the persistence of host species. Mantled howler monkeys are infected by the larvae of the bot fly Cuterebra baeri. This parasitosis produces myiasis and may have negative impacts on host health, although systematic information on the dynamics of this host-parasite relationship is very limited.

Acoustic recognition of predators by mantled howler monkeys (Alouatta palliata): A playback experiment with naïve and experienced subjects.

Objectives: When the production of antipredator behaviors is costly, prey is expected to stop displaying such behaviors and lose the ability to recognize extirpated predators. However, the loss or maintenance of predator recognition abilities is conditional on the eco-evolutionary context of prey. Here, we examined the behavioral responses of naïve and experienced mantled howler monkeys (Alouatta palliata) to simulated acoustic cues from natural predators.

Mantled howler monkeys (Alouatta palliata) show no preferential hand use in two self-directed behaviors.

Hand preference is the preferential use of one hand for a single task. Its study provides insight into the neural mechanisms underlying motor skills, perception, and cognitive functions. From a comparative perspective, it also offers a window into evolutionary history, shedding light on whether manual preferences stem from genetics, environmental influences, or a combination of both.

Leadership and the finder's advantage in mantled howler monkeys.

Leading collective movements and arriving first at feeding sites may improve food acquisition. Specifically, the first individual to discover and exploit a feeding site may gain a feeding advantage known as the "finder's advantage." The aim of this research was to verify if the probability of leading group movements to feeding sites in mantled howler monkeys (Alouatta palliata) varied by sex and reproductive status, and whether finders had higher foraging success than followers.

Mantled howler monkey males assess their rivals through formant spacing of long-distance calls.

Formant frequency spacing of long-distance vocalizations is allometrically related to body size and could represent an honest signal of fighting potential. There is, however, only limited evidence that primates use formant spacing to assess the competitive potential of rivals during interactions with extragroup males, a risky context. We hypothesized that if formant spacing of long-distance calls is inversely related to the fighting potential of male mantled howler monkeys (Alouatta palliata), then males should: (1) be more likely and (2) faster to display vocal responses to calling rivals; (3) be more likely and (4) faster to approach calling rivals; and have higher fecal (5) glucocorticoid and (6) testosterone metabolite concentrations in response to rivals calling at intermediate and high formant spacing than to those with low formant spacing.

Analytical and biological validation of a noninvasive measurement of glucocorticoid metabolites in feces of Geoffroy's spider monkeys (Ateles geoffroyi).

We report on an analytical and biological validation of a commercial cortisol enzyme immunoassay (EIA) to measure glucocorticoids (GC) in feces of Geoffroy's spider monkeys (Ateles geoffroyi). Validation of endocrinological methods for each sample matrix and study species is crucial to establish that the methods produce reliable results. For the analytical validation of the EIA, we assessed parallelism, accuracy, and precision.

Noise intensity modulates the responses of mantled howler monkeys to anthropophony.

Anthropogenic noise is a major global pollutant but its effects on primates are poorly understood, limiting our ability to develop mitigation actions that favor their welfare and conservation. In this study, we used an experimental approach to determine the impact of variation in noise intensity on mantled howler monkeys (Alouatta palliata). We conducted the study at Los Tuxtlas (México), where we studied the physiological stress (proxied via fecal glucocorticoid metabolites, fGCM) and behavioral responses of 16 males.

Behavioral responses of mantled howler monkeys to neighbor long-distance vocalizations.

Objectives: Long-distance vocalizations are used by primates in a variety of contexts and may have different functions. The long-distance vocalizations of howler monkeys (Alouatta spp.) underlie the spatial regulation of neighboring groups and could be associated with the defense of food resources.

Dog barks influence the physiological stress and behavior of a wild primate.

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.

Correlates of hormonal modulation in mantled howler monkey males, Alouatta palliata.

Objectives: The study of hormone modulation may offer important insight into the responses of individuals to environmental challenges. Here we studied C-peptide, thyroid hormone (T3), glucocorticoid (GC), and testosterone (T) metabolites of mantled howler males to assess: 1) correlations among hormones; 2) individual and temporal variation in hormone concentrations; and 3) the influence of ecological, climatic, behavioral, social, and reproductive factors on hormone variation.

Methods: We studied 10 adult males at La Flor de Catemaco (Mexico) from January 2012 to December 2016.

Demography and life-history parameters of mantled howler monkeys at La Flor de Catemaco: 20 years post-translocation.

Translocations usually aim at maintaining and enhancing wild populations. Thus, the long-term monitoring of translocated individuals is critical for assessing translocation success. In this study, we report the demographic and life-history parameters of mantled howler monkeys that were translocated to La Flor de Catemaco (Los Tuxtlas, Mexico) to determine the success of the translocation process.

One step forward, two steps backward: The frailty of howler monkey conservation in Los Tuxtlas, Mexico.

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.

The influence of anthropogenic noise on the behavior of male mantled howler monkeys.

Anthropogenic noise is increasingly disturbing natural soundscapes and affecting the physiology, behavior, and fitness of wildlife. However, our knowledge about the impact of anthropogenic noise on wild primates is scant. Here, we assess the effects of anthropogenic noise on the behavior of male mantled howler monkeys (Alouatta palliata).

Vocal and movement responses of mantled howler monkeys (Alouatta palliata) to natural loud calls from neighbors.

Loud calls (i.e., long-range acoustic signals) regulate resource competition among neighboring groups of conspecifics in several nonhuman primate species.

Maternal care according to offspring sex and maternal physical condition in mantled howler monkeys (Alouatta palliata).

The Trivers-Willard hypothesis (TWH) posits that maternal care will be biased in favor of the sex that provides the greatest fitness returns per unit of investment, depending on maternal physical condition. Our aim was to examine the TWH in mantled howler monkeys living at Los Tuxtlas (Veracruz, Mexico). The biological attributes of mantled howler monkeys (Alouatta palliata) meet the assumptions of TWH better than those of other explanations, so we expected that females in better physical condition should bias maternal care toward sons, whereas mothers in worse physical condition should bias care toward daughters.

Female reproductive energetics in mantled howler monkeys (Alouatta palliata): A follow-up study.

Objective: Reproduction entails several challenges to primate females, among which energetic costs are remarkable at certain stages of the reproductive cycle. Still, females may use behavioral and physiological strategies to cope with those challenges. We had previously reported covariation between female energetic condition through the reproductive cycle and time-budget adjustments in mantled howler monkeys (Alouatta palliata).

Factors influencing infant sex ratio in howler monkeys (Alouatta spp.): A literature review and analysis.

Objective: Frequency-dependent selection is expected to maintain infant sex ratios around parity over evolutionary time. However, over ecological time periods, infant sex ratios vary, and it has been proposed that this variation may reflect adaptive processes. In primates, there are consistent patterns of variation in infant sex ratios, although their adaptive significance remains contentious.

Isotopic niche partitioning in two sympatric howler monkey species.

Objectives: Ecological similarity between species can lead to interspecific trophic competition. However, when ecologically similar species coexist, they may differ in foraging strategies and habitat use, which can lead to niche partitioning. As the body tissues of consumers contain a stable isotope signature that reflects the isotopic composition of their diet, stable isotope analysis is a useful tool to study feeding behavior.

Sex differences in leadership during group movement in mantled howler monkeys (Alouatta palliata).

Benefits of group life depend in large part on whether animals remain cohesive, which often requires collective decisions about where and when to move. During a group movement, the leader may be considered as the individual occupying the vanguard position of the group progression, when its movement evokes following by other group members. In nondespotic societies, individuals with greater incentives to move frequently are leaders.

Reduced Introgression of Sex Chromosome Markers in the Mexican Howler Monkey ( × ) Hybrid Zone.

Interspecific hybridization allows the introgression or movement of alleles from one genome to another. While some genomic regions freely exchange alleles during hybridization, loci associated with reproductive isolation do not intermix. In many model organisms, the X chromosome displays limited introgression compared to autosomes owing to the presence of multiple loci associated with hybrid sterility or inviability (the "large X-effect").

Energetic constraints on the reproduction of female mantled howlers.

The reproductive process of female primates is energetically constrained. However, while there is extensive evidence about factors that influence the maintenance of gestation and lactation, less is known about energetic correlates of cycling and the occurrence of conception in wild primates. We examined how female physical condition affected the occurrence of conception and interbirth intervals (IBI) in female mantled howler monkeys, a species in which females experience long non-conceptive periods.

Maternal condition and maternal investment during lactation in mantled howler monkeys.

Objectives: Lactation is a costly reproductive state for females, as it may entail decreased body condition, increased morbidity, and increased mortality risk. To offset these costs, mothers should allocate investment in infant care as a function of their physical condition. Here, we assessed the relationship between maternal condition and maternal investment in wild mantled howler monkeys (Alouatta palliata) to determine: (1) whether maternal physical condition varied as a function of food availability, activity levels and feeding effort throughout lactation; (2) whether maternal investment was affected by maternal condition and offspring age.

Integrating expert knowledge and ecological niche models to estimate Mexican primates' distribution.

Ecological niche modeling is used to estimate species distributions based on occurrence records and environmental variables, but it seldom includes explicit biotic or historical factors that are important in determining the distribution of species. Expert knowledge can provide additional valuable information regarding ecological or historical attributes of species, but the influence of integrating this information in the modeling process has been poorly explored. Here, we integrated expert knowledge in different stages of the niche modeling process to improve the representation of the actual geographic distributions of Mexican primates (Ateles geoffroyi, Alouatta pigra, and A.