Environmental History of Howler Monkeys
Deep in the lush jungles of Central America lives an abundance of unique wildlife. The sounds of the jungle thrive and harmonize as the tropical birds, frogs, and insects call to one another. Within the blooming canopy, a loud howl breaks through the tropical rainforest’s natural ambience. The large black-furred primate proclaims another loud call to ward off any rivals of its own species. Using its agile limbs and prehensile tail, the howler monkey moves quickly through its ecological niche to protect its young and other members of the troop. As the largest of the New World monkeys, howlers remain an important and protected animal throughout their Latin American countries. Only two species of howlers live in the Yucatán region of Mexico: the mantled howler monkey (Alouatta palliata) and Yucatán/Guatemalan black howler monkey (Alouatta pigra). Scholars from a diverse array of fields have implemented human and non-human primate encounters in their research, including archaeologists, environmental scientists, and primatologists. Like most aspects of nature, howler monkeys and other primates have been portrayed as backdrops in most historical narratives. How have howler monkeys historically impacted Central American societies, and how have they impacted contemporary societies? What struggles do howlers face in the destructive environment of the "Anthropocene"?
According to "New World Monkeys: The Evolutionary Odyssey" by Alfred L. Rosenberger, howler monkeys belong to the Atelidae family, which feature the prehensile-tailed frugivores and folivores. All howler monkeys are classified under the unique subfamily of Alouattinae and the genus Alouatta. Known for emitting loud calls throughout their environment, a howler monkey’s infamous call measures at approximately 150 decibels and can be heard from miles across the jungle.  Their vocalizations result from an enlarged hyoid bone and extension of their larynx. Howler monkeys, specifically male howlers, use their vocal calls as a means to ward off any rival monkey troop. Additionally, the howls warn other members of their troop of any nearby potential predators. Consequently, the loud vocalizations attract the attention of many organisms, including humans.
Howlers and other species of monkeys have not only fascinated contemporary societies, but also the people of Pre-Columbian civilizations and the early European explorers of Central and South America. Very few Spanish documents provide early accounts of howlers and other Neotropical monkeys. For instance, the accounts of Hernando Colón regarded a monkey encounter that his father experienced on the island of Trinidad. Additionally, limited examples of monkey representations in Maya art and culture exist. The Maya and other Mesoamerican civilizations expressed each species of monkey differently in their art. In their article, “Revisiting Monkeys on Pots,” Prudence M. Rice and Katherine E. South analyze 97 Maya pots dated from the Classic-period. Each pot presents a visual representation of a monkey. Rice and South discuss the debates among scholars regarding the species of monkey portrayed on the pots. They explain that the three common monkeys living in the Lowland region, which included a species of spider monkey and two species of howler monkeys (Alouatta palliata and pigra), are all worthy candidates. Additionally, they assert the presence of capuchin monkeys since a pot presents an identical monkey engraving.  They describe the art of howlers as having human-like hands and with open mouths to show their vocal attributes. Whereas, the Maya feature spider monkeys with long limbs and more anthropogenic characteristics than that of other Neotropical primates, such as howlers. Though “Revisiting Monkeys on Pots” provides an excellent interpretation of Maya art regarding Neotropical monkeys, other sources contribute to this topic, as well.
Biologist Emiliano Bruner and anthropologist Andrea Cucina offer another solid source that expresses primate representations in Mesoamerican societies. Their article, “Alouatta, Ateles, and the Ancient Mesoamerican Cultures,” examines primate representation in Mesoamerican art and culture, which concludes the dominance of Ateles (spider monkeys) in Mesoamerican art compared to that of Alouatta. Utilizing the stories of the Popol Vuh, Bruner and Cucina claim that monkeys, both Alouatta and Ateles, were the gods’ second attempt at creating humans. This shows the Mesoamerican Amerindians’ consciousness regarding the evolutionary relationship between human and non-human primates. To further prove this, Cucina and Bruner explain that monkey, or monkey-like creatures, often appear in art representations of the underworld. They argue that this connection between humans and monkeys “could be linked to their ancestral state of pre- or proto-human creatures.”  Their analysis provides a thorough ethnozoological interpretation of Neotropical monkeys in Central American civilizations. However, other scholars have also delved further into the topic of ethnozoology to better understand the ethnoprimatological aspects of Mesoamerican civilizations.
In "Howler Monkeys: Developments in Primatology: Progress and Prospects," edited by Martín M. Kowalewski, Paul A. Garber, Liliana Cortés-Ortiz, Bernardo Urbani, and Dionisios Youlatos, the researchers further explore the topic of ethnoprimatology, specifically concerning howler monkeys. In their chapter titled “The Ethnoprimatology of the Howler Monkeys (Alouatta spp.): From Past to Present,” Urbani and Lorretta A. Cormier consider how humans and howler monkeys have interacted. They utilize from ethnological accounts of indigenous groups and from the archaeological record to support their arguments. Moreover, Urbani and Cormier explain that human and howler interactions remain evident through the zooarchaeological record. A tooth of an Alouatta palliata specimen was uncovered in a village of merchants at Teotihuacán, which dated to Xolalpan Period (400–650 years CE).  The chapter also discusses how contemporary indigenous groups throughout both Central and South America applied the howler in their customs and beliefs. For example, some societies implement the howler in their diets, while other societies view the consumption of such animals as taboo. Another example takes place in Mexico, where a group of researchers collected data regarding the Popoluca people and the cultural significance of local primates. In their article, “The Primate Cultural Significance Index: Applications with Popoluca Indigenous People at Los Tuxtlas Biosphere Reserve,” the research team explains that the Popoluca people have coexisted with howlers in a shared environment. Though howlers are absent in the Popoluca myths, the people believe that their calls predict the changes in the rainy and dry seasons.  These examples present how howlers impacted Central and South American societies from an anthrozoological viewpoint.
The visual representations and inclusion of howlers in Mesoamerican culture highlight their importance to Pre-Columbian Amerindians. In the modern era, the influence between the human and non-human primates have reversed targets and shifted the impact from cultural to environmental. Like many animals across the globe, howlers have gradually become victims of the "Anthropocene". In 1956, the Alouatta pigra population suffered from a jungle yellow fever epidemic. This disease was first introduced to the Americas from Africa during the Columbian exchange.  Due to hunting, deforestation, and the pet trade, humans have impacted wild howlers exponentially. Awareness and many conservation efforts have helped maintain a stable howler population throughout many Latin American countries. Robert H. Horwich’s article “Effective Solutions for Howler Conservation” focuses on the howler’s conservation in Belize. Though not in the Yucatán, the Community Baboon Sanctuary (CBS) protects howlers who thrive within the Maya region. In this article, he explores the purposes of the CBS and how their work simultaneously helps the resident wildlife, while economically helping their local communities. Organized by environmental factors that all howlers experience, his article discusses logging disturbance, hunting, and human co-existence. Horwich argues that the impact of logging disturbances on howlers and other primates vary by their tolerance and adaptability to survive in a regenerating forest. He states that human logging efforts produce “major changes in group ranging and activity patterns, in order to avoid activity.”  Horwich stresses that logging not only causes the death of many juvenile and mature howlers, but also causes higher howler infant mortality. He explains that howlers, as well as other primates, have the potential to recover once humans allow the forest to regenerate. 
Horwich explains that the conservation efforts of the CBS work with willing local farmers and landowners. Using maps of each landowner’s property, Horwich and his team formed specific plans that benefited both the landowner and the howlers. With the support of local governments, the plan included leaving strips of forestry between milpa cuttings, properties, and near rivers. Additionally, the strategy included leaving “aerial pathways of trees across large cleared areas, and to leave specific food trees for howlers.”  Horwich found that local participants financially benefited due to the increase in ecotourism. Though this research is relatively old, the issues discussed in this article still remain important issues today. Horwich teams with Taylor V. Stein, Jane Southworth, and Miriam S. Wyman to coauthor another study titled “Does Population Increase Equate to Conservation Success? Forest Fragmentation and Conservation of the Black Howler Monkey” to examine the forest fragmentation and its effect on howler populations, or Baboon populations as locals call them. This relatively recent study applies modern spatial sciences and methodologies to present a more in-depth study. Analyzing his findings, Horwich pleads that more landowners must become active in forest fragmentation. He states that the howler’s “ability to minimize energy expenditure through small home ranges (and short-day ranges), relatively small troop size, and highly folivorous and flexible diets improves conservation likelihood.”  Though this examination emphasizes on forests and habitat loss, howlers remain the primary fatality disturbed by these anthropogenic changes.
Whether howlers influenced aspects of Mesoamerican culture or humans altered the howler’s environment, their interactions have clearly impacted each other throughout history. This subject has attracted numerous scholars from their many specialized fields, bringing together the life and social sciences for the purpose of conserving this unique animal. Though attempts to protect howlers exist, more efforts remain essential. Humans have continued to contribute to the "Anthropocene" extinction event, which risks the future of howlers becoming its next potential target. More attention, academic research, and conservation efforts will keep the howler monkey a living Mesoamerican treasure.