My research is conducted in collaboration with the Indigenous Maijuna people of Sucusari, Peru, Georgetown University, George Mason University, OnePlanet, the ACEER Foundation, and the Peruvian Fulbright Commission. I have three main research objectives:
1. Understand the ecological and cultural roles and significance of mineral licks.
2. Understand how individual hunters' decision-making practices influence mammal conservation.
3. Understand the impacts of subsistence hunting on mammal behavior at mineral licks.
Mineral licks are naturally-occurring sites in the rainforest which have minerals and clays locked in the soil. Animals need these minerals and clays, so they visit these sites and consume the soil. However, natural predators and hunters will also commonly visit these sites looking for prey. Mineral licks often have exposed bedrock, where erosion weathers the rock and leaches minerals into the soil. Most of these sites are difficult to find because they may be in remote areas and they don't look like much more than a muddy clearing. The presence and characteristics of these licks are, accordingly, very poorly documented and understood.
At these sites, I take photos and measurements and leave motion-activated camera traps, which record all the animals coming to visit the lick.
To measure hunting levels and the cultural relevance of these sites, I do interviews with hunters using a technique called participatory mapping. In their interviews, hunters draw on a map where they went hunting during the week, and indicate the locations of animal species that they either saw or killed. This spatial data is analyzed to give context to the camera trap photos!
Photo by Wilfredo Martinez
Differential use of game species in an indigenous Amazonian community: Navigating economics, subsistence, and social norms
Hunting is a key subsistence strategy and source of income and food security for rural communities throughout the world. Hunters often gift game meat to their friends or family in return for reciprocation, or other social benefits. We used interviews to assess how hunters in an Amazonian Indigenous community navigate the economic, subsistence, and social aspects of hunting. We found that hunters typically sell the most valuable and preferred species whole except for the head, gift better cuts of less-preferred species and consume the lowest quality portions of non-preferred species. We conclude that hunters use species and portions of carcasses differentially to maximize profit and food security and fit the social norms of the community. Understanding the social systems surrounding wild game use in rural Amazonian communities provides insight into how the loss of wild mammals could influence food security and social relationships.
Griffiths, B. M. & Gilmore, M. P. In Press. Differential use of game species in an indigenous Amazonian community: Navigating economics, subsistence, and social norms. Journal of Ethnobiology.
Patterns of visitation of the Linneaus's two-toed sloth (Choloepus didactylus) at Amazonian mineral licks
Mineral licks are essential to many species of mammals and birds in the Amazon rainforest, including the Linnaeus’s two-toed sloth (Choloepus didactylus). While sloths have been recorded at mineral licks, visitation of the two-toed sloth at mineral licks has not been described in detail. We used camera traps to observe sloth visitation at 53 mineral lick sites and generalized linear mixed-effects model to evaluate patterns in visitation. We recorded a visitation rate of 29.39 visits per 100 camera nights, with a peak activity time of 22.00 h. Our model results suggest that sloth visitation at mineral licks may be related to differential habitat selection based in part on elevation, slope, and distance from rivers and streams. This study describes the largest dataset on sloth visitation at mineral licks to date, provides key natural history information on this cryptic mammal, and contributes to our understanding of the ecological importance of mineral licks.
Stewart, H., Tighe, E., & Griffiths, B. M. 2022. Patterns of visitation of the Linnaeus’s two-toed sloth (Choloepus didactylus) at Amazonian mineral licks. European Journal of Wildlife Research, 68:25.
Revisiting optimal foraging theory (OFT) in a changing Amazon: Implications for conservation and management
Hunter decision-making influences prey selection and is key to understanding the impacts of hunting on biodiversity. Optimal foraging theory (OFT) is often used to describe the decision-making and prey selection of subsistence hunters. We examined the behavior and game meat use of hunters in an indigenous Amazonian community and used free listing and generalized linear mixed-effects models under the framework of OFT to assess the decision-making of individuals who hunt for economic gain and subsistence. We found that prey selection generally followed OFT, and was influenced by hunters’ skills, patch choice, and characteristics of the prey encountered. Hunters preferred paca (Cuniculus paca), collared peccary (Pecari tajacu), and brocket deer (Mazama americana), and only partially preferred tapir (Tapirus terrestris) and large-bodied primates likely due to economic influences such as access to markets and prices, contrary to OFT predictions.
Griffiths, B. M., Bowler, M., Kolowski, J., Stabach, J., Benson, E. L. & Gilmore, M. P. 2022. Revisiting optimal foraging theory (OFT) in a changing Amazon: Implications for conservation and management. Human Ecology.
Assessing the accuracy of distance- and interview-based measures of hunting pressure
In the Amazon Rainforest, the sustainability of hunting is difficult to model. Accurate sustainability models for hunting of mammal populations require a spatially explicit measure of hunting pressure. Because field-based measures of hunting pressure are time and labor-intensive, distance-based proxies for hunting pressure are frequently used. In this study, we tested accuracy of distance-based parameters in predicting measured hunting pressure obtained through interviews for a riverine community in the Peruvian Amazon. We examined the spatial accuracy of the interviews and investigated the minimum requirements for spatial assessment of hunting pressure based on interviews. Results illustrate that hunter-reported animal kill locations were accurate to within a mean of 1 km. Interview effort results showed that approximately 4 months of interviews capturing at least 50% of hunts are necessary to obtain a complete measure of hunting pressure across the landscape. Generalized linear models identified a novel spatially explicit approach that explained 59% of the deviance in measured hunting pressure. Our model was based on distances from locations that are easily obtained through remotely sensed imagery, participatory mapping, and terrain characteristics, highlighting that biologically relevant and spatially explicit estimates of hunting pressure can be obtained without lengthy field-based methods. Hunting pressure across a landscape can be accurately predicted from remote sensing, participatory mapping, and terrain characteristics.
Griffiths, B. M., Kolowski, J., Bowler, M., Gilmore, M. P., Lewis, F., Benson, E., & Stabach, J. 2021. Assessing the accuracy of distance- and interview-based measures of hunting pressure. Conservation Science and Practice, e592.
Dissimilarities among species assemblages at Amazonian mineral licks
Mineral lick elevation, size, and distance to the closest human community are all associated with mammal and bird species visitations. The most frequently hunted licks have similar species assemblages. Results indicate high variability in species assemblages at different mineral licks suggesting different species-specific resource needs at different licks.
Griffiths, B. M., Cooper, W. J., Bowler, M., Gilmore, M. P., & Luther, D. (In Press). Dissimilarities among species assemblages at Amazonian mineral licks. BioTropica.
Mineral licks are key ecological resources for many species of birds and mammals in Amazonia, providing essential dietary nutrients and clays, yet little is known about which species visit and their behaviors at the mineral licks. Studying visitation and behavior at mineral licks can provide insight into the lives of otherwise secretive and elusive species. We assessed which species visited mineral licks, when they visited, and whether visits and the probability of recording groups at mineral licks were seasonal or related to the lunar cycle. We camera trapped at 52 mineral licks in the northeastern Peruvian Amazon and detected 20 mammal and 13 bird species over 6,255 camera nights. Generalized linear models assessed visitation patterns and re- cords of groups in association with seasonality and the lunar cycle. We report nocturnal curassows (Nothocrax urumutum) visiting mineral licks for the first time. We found seasonal trends in visitation for the black agouti (Dasyprocta fuliginosa), red howler monkey (Alouatta seniculus), blue-throated piping guan (Pipile cumanensis), red brocket deer (Mazama americana), collared peccary (Pecari tajacu), and tapir (Tapirus terrestris). Lunar trends in visitation occurred for the paca (Cuniculus paca), Brazilian porcupine (Coendou prehensilis), and red brocket deer. The probability of recording groups (>1 individual) at mineral licks was seasonal and related to lunar brightness for tapir. Overall, our results provide important context for how elusive species of birds and mammals interact with these key ecological resources on a landscape scale. The ecological importance of mineral licks for these species can provide context to seasonal changes in species occupancy and movement.
Griffiths B. M., Bowler, M., Gilmore, M. P., & Luther, D. A. (2020). Temporal patterns of visitation of birds and mammals at mineral licks in the Peruvian amazon. Ecology and Evolution. https://doi.org/10.1002/ece3.7006
Background: The overhunting of wild species is a major threat to biodiversity in the Amazon; yet, managed, sustainable hunting is widely considered part of the solution to conserving wildlife populations. Hunting is both a culturally important activity for Indigenous people and provides an important food source. Mineral licks, a focal point of hunting in Amazonia, are naturally occurring areas in the forest where animals come to obtain essential minerals or clays that are thought to neutralize plant-based alkaloids. We sought to better understand the socio- cultural importance of mineral licks to the Maijuna Indigenous group to inform the sustainable management of this habitat and associated wildlife populations.
Methods: Semi-structured interviews, focus groups, and participatory mapping were carried out with hunters to assess the significance of mineral licks and their associated animal resources as well as to determine how the relationship that the Maijuna have with mineral licks has changed over time.
Results: Mineral licks are culturally significant and useful to the Maijuna in a variety of ways. Hunters target these areas year-round both during the day and night, and animals killed are consumed for subsistence and sold to generate income. The spatial use of mineral licks across the landscape is determined on the generational family level, with families maintaining exclusive use of selected mineral licks and excluding access by other hunters. The Maijuna also have traditional beliefs for why animals visit mineral licks, which is linked to the traditional Maijuna story of the creation of the first tapir. The relationship that the Maijuna have with mineral licks has changed considerably over time, which is observed through changes in hunting technologies and methods as well as the loss of traditional knowledge and beliefs.
Conclusions: Traditional and current Maijuna hunting conventions, in which families maintain exclusive use of selected mineral licks, likely reduce the probability of overexploitation of animal populations. Community-based management plans for mineral licks in Maijuna lands and beyond must incorporate and account for the multiple cultural and economic needs of local communities while also striving toward ecological sustainability. Country-wide strategies to conserving forests and using them sustainably should aim to ensure land tenure for rural peoples and encourage management that incorporates traditional sustainable hunting conventions.
Gilmore, M.P., Griffiths, B.M., & Bowler, M., 2020. The socio-cultural significance of mineral licks to the Maijuna of the Peruvian Amazon: implications for the sustainable management of hunting. Journal of Ethnobiology and Ethnomedicine 16, 1–10.
Many herbivorous and frugivorous Amazonian species, including several arboreal animals, feed on earth and water at mineral licks in the Amazon region to supplement their diet with micronutrients and clays. These species are vulnerable to predation during this activity. We recorded an adult Brazilian porcupine (Coendou prehensilis) being predated by an adult male ocelot (Leopardus pardalis) while drinking water at a mineral lick in the Maijuna-Kichwa Regional Conservation Area (MKRCA) in northeastern Loreto, Peru. This observation provides direct evidence arboreal species like the porcupine, which move slowly on the ground, are particularly vulnerable to terrestrial predators while visiting mineral licks. Mineral licks are important in the diets and ecology of Amazonian mammals, but arboreal prey must balance the trade-off between using the resource and being hunted. We suggest that mineral licks may be hotspots of risk in Amazonian prey species' landscape of fear.
Griffiths B. M., Gilmore M. P., & Bowler M. (2020). Predation of a Brazilian porcupine (Coendou prehensilis) by an ocelot (Leopardus pardalis) at a mineral lick in the Peruvian Amazon. Food Webs, 24, e00148. http://dx.doi.org/10.1016/j.fooweb.2020.e00148
Infanticide by males is a phenomenon common in species in which the reproductive output of large numbers of females can be monopolized by a small number of males. It is thought to increase a male’s fitness, at the expense of the fitness of the infant’s parents, by bringing females into season more quickly. Infanticide by males has been recorded in just three cetacean species. We report aggressive behavior suggestive of infanticide in a fourth, the Amazon river dolphin (Inia geoffrensis). We observed and photographed a series of attacks on a neonate Amazon river dolphin by a large male, with apparent protective behavior by the mother. Although infanticide was not confirmed, the forceful, aggressive behaviors were highly suggestive of infanticidal behavior and represent another important data point for comparative studies of infanticide in mammals. Amazon river dolphins may have a polygynous, polyandrous, or promiscuous mating system, the latter two of which are not the norm in species in which the reproductive output of large numbers of females are monopolized by a small number of males. However, sexual dimorphism, high rates of aggression by males, socio-sexual object-carrying displays by males, and a long interbirth interval suggest that successful male Amazon river dolphins may be able to monopolize a large proportion of mating opportunities, and it is plausible that male dolphins can improve their reproductive success by bringing females into estrous sooner by killing the offspring of other males.
Bowler, M. T., Griffiths, B. M., Gilmore, M. P., Wingfield, A., & Recharte, M. (2018). Potentially infanticidal behavior in the Amazon river dolphin (Inia geoffrensis). Acta Ethologica, 1–5.