Mountain Gorillas Research Articles

Mandibular corpus shape is a taxonomic indicator in extant hominids

The aim of this study is to understand whether the shape of three sub-regions of the mandibular corpus (the alveolar arch, corpus at M1 and posterior symphysis) are useful for making taxonomic assessments at the genus and species levels in extant hominids. We use data taken from 3D surface scans of the mandibular corpus of seven extant hominid taxa: Gorilla gorilla gorilla, Gorilla beringei graueri, Homo sapiens, Pan paniscus, Pan troglodytes schweinfurthii, Pongo abelii, and Pongo pygmaeus pygmaeus to generate four shape variables: alveolar arch shape (AAS), corpus shape at M1 (CSM1 ), posterior symphysis shape at the midline (PSSM), and posterior symphysis shape (PSS). To ascertain how reliable each mandibular shape variable is for assessing taxonomy, we ran canonical discriminant and discriminant function analysis, reporting cross-validated results. Using a combination of three mandibular corpus shape variables, 99% of specimens were classified correctly for genus-level analyses. A maximum of 100% of Pan specimens, 94% of Gorilla specimens and 96% of Pongo specimens were classified correctly at the species level when up to three mandibular shape variables were included in the analyses. When mandibular corpus variables were considered in isolation, posterior symphysis shape yielded the highest overall correct classification results. The high taxonomic classification rates at both the genus and species level, using 3D surface data and advanced quantification techniques, show that the shape of the alveolar arch, corpus at M1 and symphysis can distinguish extant hominid taxa. These findings have implications for assessing the taxonomy of extinct hominid specimens which preserve these mandibular sub-regions.

Capacity Building in the Congo Basin: Rich Resources Requiring Sustainable Development

The Congo Basin is a unique freshwater ecosystem supporting hundreds of millions of people and a crucial part of regulating Earth’s water cycle. Increasing international attention on its resource potential brings worrying pressures to this understudied region. Equitable collaboration is the key to understanding this complex, interconnected system and enabling its sustainable development.

Lack of Rule-Adherence During Mountain Gorilla Tourism Encounters in Bwindi Impenetrable National Park, Uganda, Places Gorillas at Risk From Human Disease.

Mountain gorillas (Gorilla beringei beringei) are an endangered primate species, with ~43% of the 1,063 individuals that remain on the planet today residing in Bwindi Impenetrable National Park (BINP) in southwestern Uganda. These primates are at the heart of a growing tourism industry that has incentivized their continued protection, but close proximity between humans and gorillas during such encounters presents well-documented risks for disease transmission. The Uganda Wildlife Authority (UWA) has developed rules to help protect the health of the gorillas, limiting each habituated gorilla group to a single 60 min visit each day by a group of no more than 8 tourists, and emphasizing that humans maintain a >7 m distance from gorillas at all times. A number of studies have documented that not all tour groups respect these rules. This project assesses rule-adherence during gorilla tourism encounters at BINP using both observational and survey-based data collected during the tourism high season between May and August, 2014. Observational data from 53 treks reveal that groups of 1–11 tourists engaged in gorilla viewing encounters between 46 and 98 min in duration. Although 96% of pre-trek briefings conducted by park rangers emphasized the need to maintain >7 m human-gorilla spacing, the 7 m distance rule was violated in over 98% (52 out of 53) of the tours examined in this study. Observational data were collected at 2 min intervals during gorilla-viewing encounters, documenting the nearest distance between any tourist and a gorilla (n = 1,604), of which 1,094 observations (68.2%) took place at a distance less than or equal to 7 m. Importantly, the 7 m rule was violated in visits to all of the gorilla groups habituated during the time of the study. In 224 observations (~14%, per 1,604 total), human-gorilla spacing was 3 m or less. Survey data (n = 243) revealed promising opportunities to improve tourist understanding of and adherence to park rules, with 73.6% of respondents indicating that they would be willing to utilize a precautionary measure of wearing a face-mask during encounters to protect gorilla health.

Intragroup Behavioral Changes Following Intergroup Conflict in Mountain Gorillas (Gorilla beringei beringei)

Group-living animals face a number of threats from extragroup conspecifics: from individuals seeking mating opportunities to rival groups attempting to access limited resources. The consequences of intergroup interactions can therefore include loss of mates, increased energy expenditure, and injury or death. There is increasing evidence that aggressive intergroup interactions can affect subsequent intragroup behavior, and that such post-conflict behavior may be directly related to the threats posed by different opponent groups (e.g., familiar vs. unfamiliar). However, empirical evidence for changes in intragroup behavior following intergroup conflict in social animals is limited. We compared the proximity and behavior of group members before and after 84 aggressive intergroup interactions involving 14 study groups of wild, habituated mountain gorillas (Gorilla beringei beringei) in Volcanoes National Park, Rwanda. Intergroup conflict affected subsequent intragroup behavior in several ways. We found that immediate movement away from the opponent following intergroup conflict was less likely between familiar groups compared to unfamiliar groups. However, both winning and losing groups spent twice as much time moving post-conflict, and losing groups spent less time resting. There was an increase in female intragroup affiliative interactions and a decrease in male intragroup agonistic interactions post-conflict. These results demonstrate that such intergroup contests can influence intragroup dynamics beyond the immediate period of interaction.

The Protection of the Gorilla (Gorilla Beringei Graueri) From Itombwe in the Democratic Republic of the Congo (DRC): A Case for Reconciling Environmental and Property Rights

The Protection of the Gorilla (Gorilla Beringei Graueri) From Itombwe in the Democratic Republic of the Congo (DRC): A Case for Reconciling Environmental and Property Rights

Making space for birds: Sourcing solutions from the mountain gorilla conservation model in Rwanda

Rwanda being one of the most densely populated countries in Africa, a large proportion of its native vegetation has been converted into agriculture and settlements, leading to the extensive loss and degradation of natural habitats, with significance for birds as well as other taxa. Despite this, tangible success has been attained in the conservation of mountain gorillas thanks to the high priority afforded to this species and the vigorous protection of its habitats. This article reviews the current conservation approaches in Rwanda, and their effectiveness in addressing threats to the country’s avifauna. Drawing lessons from the conservation of the mountain gorilla approach, and with reference to the principles of Systematic Conservation Planning, this paper argues that the creation of more reserves complementing existing protected areas, the development of bird-related tourism, and a multilevel collaboration of stakeholders at national and regional level, in which the public play a strong role, are crucial for the long-term conservation of birds. The aim of this analysis is both to provide policy options for Rwanda and to suggest an approach to conservation practice for wider application that is scalable and transferable within a developing country context.

Perceptions and Behaviors of Indigenous Populations Regarding Illegal Use of Protected Area Resources in East Africa's Mountain Gorilla Landscape.

Illegal activities and use of park resources are the main challenges facing mountain gorilla (Gorilla beringei beringei) conservation and the protection of their habitats in the East Africa's Greater Virunga Transboundary Landscape (GVTL). Indigenous residents around GVTL are considered the primary illegal users of park resources. Despite this, there is limited understanding of the current and past perceptions of indigenous residents living in communities adjacent to two GVTL parks; Volcanoes National Park in Rwanda and Mgahinga Gorilla National Park in Uganda. Equally, there is also limited understanding regarding the actual incidences of illegal activities inside both parks. This paper addresses these gaps. Perception data were collected from indigenous residents living adjacent to both parks. Further, Ranger-based Monitoring (RbM) data from both parks were analyzed to determine actual numbers and types of illegal activities over the 9-year period. Interestingly, findings indicated that residents perceived the prevalence of illegal activities to be decreasing across GVTL. To the contrary, RbM findings indicated that the number of actual illegal activities was increasing significantly, particularly in Volcanoes National Park. The discrepancy found between the two perspectives provides for a discussion of the social biases potentially present in these data, and their implications for management. Results also illuminated the subsistence-related nature of most illegal behaviors and suggest that to reduce illegal activities and local dependency on park resources, park management must work with communities and support them in tapping into alternative livelihoods and finding ways to address community household subsistence needs.

Estimating abundance and growth rates in a wild mountain gorilla population

AbstractMonitoring population size and growth over time is vital for the conservation of endangered species. Mountain gorillas Gorilla beringei beringei remain in two small populations that span the borders of the Democratic Republic of Congo, Rwanda and Uganda. Each population contains two subpopulations that receive differing levels of protection: the monitored groups are visited daily by park staff and researchers and can be counted by sight, whereas the number and growth rate of unmonitored gorillas must be estimated indirectly. Here, we re‐analyze published data from a survey in 2010 combined with new results from a survey conducted during two sampling occasions in 2015 and 2016 to estimate mountain gorilla abundance and growth in the Virunga Massif between 2010 and 2016. Using genetic analysis of non‐invasively collected samples and two capture–mark–recapture estimates, we estimated that the 186 detected genotypes represented 221 (95% credible interval: 204–243) to 251 (205–340) unmonitored gorillas in 2016. Together with the 418 monitored gorillas, the overall population of the Virunga Massif thus reached 639 (622–661) to 669 (623–758) individuals. We estimated the growth of the entire Virunga Massif population at about 3% per year, but determined that the growth of the monitored gorillas (4.4%) mainly drove that increase. In contrast, the trend of the unmonitored subpopulation could not be determined with confidence because both models provided 95% CI that encompassed zero: 0.5% per year (−0.7% to +1.7%) and 1.1% (−2.7% to +4.4%). While the overall growth rate represents a rare success story for primate conservation, our results highlight the need for greater protection of unmonitored gorillas.

Faster growth corresponds with shallower linear hypoplastic defects in great ape canines

Deeper or more ‘severe’ linear enamel hypoplasia (LEH) defects are hypothesized to reflect more severe stress during development, but it is not yet clear how depth is influenced by intrinsic enamel growth patterns. Recent work documented inter- and intraspecific differences in LEH defect depth in extant great apes, with mountain gorillas having shallower defects than other taxa, and females having deeper defects than males. Here, we assess the correspondence of inter- and intraspecific defect depth and intrinsic aspects of enamel growth: enamel extension rates, outer enamel striae of Retzius angles, and linear enamel thickness. Thin sections of great ape canines (n = 40) from Gorilla beringei beringei, Gorilla gorilla gorilla, Pan troglodytes, and Pongo spp. were analyzed. Enamel extension rates were calculated within deciles of enamel-dentine junction length. Linear enamel thickness and the angle of intersection between striae of Retzius and the outer enamel surface were measured in the imbricational enamel. Mountain gorillas have faster enamel extension rates and shallower striae angles than the other taxa examined. Mountain gorillas have thinner imbricational enamel than western lowland gorillas and orangutans, but not chimpanzees. In the combined-taxon sample, females exhibit larger striae angles and thicker imbricational enamel than males. Enamel extension rates are highly negatively correlated with striae angles and LEH defect depth. Enamel growth variation corresponds with documented inter- and intraspecific differences in LEH defect depth in great ape canines. Mountain gorillas have shallower striae angles and faster extension rates than other taxa, which might explain their shallow LEH defect morphology and the underestimation of their LEH prevalence in previous studies. These results suggest that stressors of similar magnitude and timing might produce defects of different depths in one species or sex vs. another, which has implications for interpretations of stress histories in hominins with variable enamel growth patterns.

Cryptosporidium and giardia species in newly and previously habituated gorillas and nearby water sources in Bwindi Impenetrable National Park, Uganda.

Introductioncryptosporidium and giardia are of great one health significance and major cause of protozoan diarrhea in humans and primates; they are found in the faecal matter of animals and humans and also in contaminated water and soil as well. Therefore, we aimed at establishing the prevalence and shedding intensity of faecal Cryptosporidium and giardia in the Newly Habituated Mountain Gorillas (NHMG) and Previously Habituated Mountain Gorillas (PHMG) and in selected water sources within the gorilla home ranges in the month of January 2018.Methodswe conducted a cross sectional study in the southern sector of Bwindi Impenetrable National Park where a total of 56 faecal samples from both NHMG (34) and PHMG (22) and 30 water samples were purposively collected. Faecal and water samples were transported in a cooler box at 4ºC to Makerere University Parasitology Laboratory for analysis. The samples were analyzed using modified Ziehl-Neelsen technique and Ether concentration method for Cryptosporidium and giardia respectively.Resultsthe prevalence of cryptosporidium was established as 13 (59.1%), 15 (44.1%) and 7 (23.3%) in PHMG, NHMG and water respectively. The mean concentration of the oocysts per gram was 222±52.9 in PHMG, 174±41.5 in NHMG and 31±13.2 in water. The prevalence of giardia was 3 (13.6%), 4 (11.8%) and 3 (10%) in PHMG, NHMG and water respectively. The mean concentration of the oocysts per gram was 34±19.9 in PHMG, 25±12.4 in NHMG and 5±2.9 in water. There was no significant difference in both the prevalence of cryptosporidium (p>0.05) and giardia (p>0.05) in the PHMG and NHMG. This indicates that there is high risk of cross infection among the gorillas within the forest sharing similar home ranges.Conclusionthe park authorities should ensure that procedures for proper waste disposal while in the forest are properly followed, water drawn for drinking from the forest should be avoided. Further research should be carried out to identify whether the strains of the parasites found in water or other animals in the forest are the same with strains in gorilla dung in order to confirm cross infection.

Pelvic shape variation among gorilla subspecies: Phylogenetic and ecological signals

Gorillas occupy habitats that range in elevation from 0 to 3850 m. Populations at higher elevations tend to be less arboreal than lowland populations. Variation in habitat-specific behaviors among closely related populations makes gorillas a unique model to study the relationship between locomotion and morphology. The pelvis reflects differences in locomotion in other primates, and thus may also reflect locomotor differences among gorillas. We tested the hypothesis that pelvic morphology exhibits clinal variation across elevation within Gorilla. Using 3D geometric morphometrics and principal components analysis (PCA), we characterized pelvic shape in three gorilla subspecies representing 14 localities across gorillas' full elevation range: western lowland gorillas (Gorilla gorilla gorilla), mountain gorillas (Gorilla beringei beringei), and Grauer's gorillas (Gorilla beringei graueri). We found that the first principal component (PC1) usually reflects differences between western and eastern gorillas in the lateral margin of the ilium and, in males, the obturator foramen. When sexes are considered together, the second principal component (PC2) indicates some separation between G. b. beringei and G. b. graueri, albeit with considerable overlap, corresponding to the shape of the iliac crest. When sexes were analyzed separately, there was no distinction. Phylogenetic generalized least squares regression was used to evaluate the relationship between elevation and pelvic shape under varying phylogenetic assumptions. Models were compared to assess how phylogenetic adjustment affects model fit. Neither of the first two PCs nor overall shape yielded a significant relationship with elevation in any of the pooled-sex and individual-sex samples. This suggests that covariation between pelvic morphology and elevation is sex-specific and dependent on phylogenetic assumptions. Our results find complex interactions between sex, phylogeny, elevation, and pelvic morphology, suggesting that there is not one ecomorphological pattern that characterizes all gorillas.

Recent decline in vegetative regeneration of bamboo (Yushania alpina), a key food plant for primates in Volcanoes National Park, Rwanda

The African montane bamboo Yushania alpina provides both habitat and food for many species in the Albertine Rift region. In Volcanoes National Park (VNP), Rwanda, it is especially important as a key food resource for the Endangered mountain gorilla Gorilla beringei beringei and Endangered golden guenon Cercopithecus mitis kandti. We examined temporal and spatial variation in bamboo shoots regeneration and consumption by primates, monitored between 2013 and 2018 in 82 16-m2 plots located along transects in VNP. Our analyses revealed a decline in vegetative regeneration of bamboo in recent years, which is mirrored by a decline in bamboo shoot consumption by primates; but an increase in proportional intake. Local declines in regeneration are potentially due to high intensities of herbivory, decreased amounts of rainfall during growing seasons, and natural processes that form part of the life cycle of bamboo. Moreover, spatial variation in bamboo regeneration can be explained by elevation, as well as by stand-level variation in soil acidity, vegetation density, and the density of dead bamboo culms. We discuss the potential mechanisms underlying observed temporal and spatial variations and outline possible effects of a decline in bamboo regeneration for primates and other aspects of biodiversity in VNP.

Abundance and spatial distribution of the main food species for mountain gorillas in the Virunga Massif, Rwanda

The conservation of endangered species can benefit from a clear understanding of the quantity and distribution of their main foods. The population of mountain gorillas (Gorilla beringei beringei) living in the Virunga Massif of Rwanda, Uganda, and Democratic Republic of Congo has doubled in size since the 1980s, due to success in conservation efforts in and around their habitat. However, this increase in population size along with pressures on gorilla habitat raises concerns about spatial-temporal changes in the gorillas’ food plants. This study modelled the abundance and distribution of gorilla food species in the Virunga Massif. A total of 1050 vegetation recordings were collected on five plant species that are known to be frequently consumed by gorillas in one region of the Virungas, the Karisoke area. Two types of datasets collected along vegetation zones were combined: one with plant abundance expressed with Braun-Blanquet scores; and the other with abundance expressed as biomass. Moreover, ecological characteristics of locations where these species occur were extracted from satellite imagery. Analysis of variance and linear regression models were used to examine relationships between food species abundances and predictor variables. Subsequently, maps for the food species were created using boosted regression trees (BRTs). The abundance of species differed across vegetation zones, and the differences were statistically significant among vegetation zones with enough species observations. The accuracy of the BRTs indicated greater than random predictions (AUC > 0.65). This study shows the suitable areas for these gorilla food species and relevant ecological variables determining their distribution. The results provide insights into habitat occupancy by mountain gorillas, and help to design a baseline for monitoring changes in the abundance of gorilla food species under changing climate and anthropogenic pressure.

Water games by mountain gorillas: implications for behavioral development and flexibility-a case report.

Functions of play, which may be performed solo or in a social context, include motor training and behavioral flexibility. Play is often more common in infancy and the juvenile period, although it also occurs in adults of many species. In contrast to social play, few studies have investigated solitary play. Here, we present new empirical data on solitary water play in a subadult and two adult mountain gorillas in Bwindi Impenetrable National Park, Uganda, observed on three different days between January and February 2018. Focal sampling was used to record the behavior of the individuals interacting with water. Movements included vigorous rotation of the arms, splashing the water, tilting the head, making a play face, and sweeping with the hands to create waves on the water surface. One of the episodes represents the first vigorous display of splashing water ever reported for Bwindi gorillas. Our observations highlight three significant components of mountain gorilla development and behavior: play, behavioral flexibility, and exploration.

Nutritional composition of the diet of the western gorilla (Gorilla gorilla): Interspecific variation in diet quality.

To meet nutritional needs, primates adjust their diets in response to local habitat differences, though whether these dietary modifications translate to changes in dietary nutrient intake is unknown. A previous study of two populations of the mountain gorilla (MG: Gorilla beringei) found no evidence for intraspecific variation in the nutrient composition of their diets, despite ecological and dietary differences between sites. One potential explanation is that nutritional variability in primate diets requires greater ecological divergence than what was captured between MG sites, underpinning environmental differences in the nutrient quality of plant foods. To test whether Gorilla exhibits interspecific variation in dietary composition and nutrient intake, we studied the composition and macronutrients of the western gorilla (WG: Gorilla gorilla) staple diets and compared them with published data from the two MG populations. We recorded feeding time and food intake of four adult female WGs from one habituated group over a period of 11 months (December 2004-October 2005) at the Mondika Research Center, Republic of Congo, allowing for assessment of seasonal patterns of nutrient intake. Staple diets of WGs and MGs diverged in their dietary and macronutrient composition. Compared to MGs, the staple diet of WGs (by intake) contained higher proportions of fruit (43%) and leaf (12%) and a lower proportion of herb (39%), resulting in a higher intake of total nonstructural carbohydrate and fiber and a lower intake of crude protein. Staple gorilla fruits and herbs differed in nutrient quality between sites. Gorillas exhibit nutritional flexibility that reflects ecological variation in the nutrient quality of plant foods. Since dietary quality typically affects rates of growth and reproduction in primates, our results suggest that interspecific differences in nutrient intake and food quality may shape differences in gorilla nutrient balancing and female life history strategies.

Commensal bacterial sharing does not predict host social associations in kangaroos.

Social network analysis has been postulated as a tool to study potential pathogen transmission in wildlife but is resource-intensive to quantify. Networks based on bacterial genotypes have been proposed as a cost-effective method for estimating social or transmission network based on the assumption that individuals in close contact will share commensal bacteria. However, the use of network analysis to study wild populations requires critical evaluation of the assumptions and parameters these models are founded on. We test (a) whether networks of commensal bacterial sharing are related to hosts' social associations and hence could act as a proxy for estimating transmission networks, (b) how the parameters chosen to define host associations and delineate bacterial genotypes impact inference and (c) whether these relationships change across time. We use stochastic simulations to evaluate how uncertainty in parameter choice affects network structure. We focused on a well-studied population of eastern grey kangaroos (Macropus giganteus), from Sundown National Park, Australia. Using natural markings, each individual was identified and its associations with other kangaroos recorded through direct field observations over 2years to construct social networks. Faecal samples were collected, Escherichia coli was cultured and genotyped using BOX-PCR, and bacterial networks were constructed. Two individuals were connected in the bacterial network if they shared at least one E.coli genotype. We determined the capacity of bacterial networks to predict the observed social network structure in each year. We found little support for a relationship between social association and dyadic commensal bacterial similarity. Thresholds to determine host associations and similarity cut-off values used to define E.coli genotypes had important ramifications for inferring links between individuals. In fact, we found that inferences can show opposite patterns based on the chosen thresholds. Moreover, no similarity in overall bacterial network structure was detected between years. Although empirical disease transmission data are often unavailable in wildlife populations, both bacterial networks and social networks have limitations in representing the mode of transmission of a pathogen. Our results suggest that caution is needed when designing such studies and interpreting results.

Responses to dead and dying conspecifics and heterospecifics by wild mountain gorillas (Gorilla beringei beringei) and chimpanzees (Pan troglodytes schweinfurthii).

Comparative ["evolutionary")] thanatology is devoted to investigating how animals respond to signs of death and dying, in conspecifics and other species. Responses to corpses often involve fear and confusion, and "deceased infant carrying" by females is widespread in nonhuman primates. Such behavior could result from "animacy detection malfunctions" (Gonçalves and Biro in Philos Trans R Soc (B) 373:20170263, 2018): corpses have attributes of animate agents, but-like objects-they do not act, but instead are acted upon by outside forces. Many or most nonhuman primates have core cognitive mechanisms for detecting animacy, but these might not resolve this paradox. Skeletons of conspecifics, seriously injured or ill individuals behaving oddly and not responding as expected to social acts and signals, and corpses, skeletons, and sick or injured individuals belonging to other species could trigger milder animacy detection malfunctions. A central question is whether any nonhuman primates learn from experience that death involves permanent loss of biological functionality and is universal. The relevant literature is mostly anecdotal or devoted to case studies, and this question is open. In response to calls for more information, I describe 25 cases of responses to corpses, skeletons, and mortally injured or ill individuals, both conspecifics and heterospecifics, seen during fieldwork on mountain gorillas (Gorilla beringei beringei) and chimpanzees (Pan troglodytes schweinfurthii). Observations were generally consistent with the animacy detection malfunction hypothesis, although cases of prolonged deceased infant carrying are problematic. Also, one case in gorillas apparently involved sympathetic concern for a dying individual, and sympathetic concern might have occurred in a chimpanzee case.

Effect of mountain gorilla (<i>Gorilla beringei beringei</i>) population growth to their key food plant biomass in Volcanoes National Park, Rwanda

High densities of large herbivores can have detrimental effects on plant biomass. Understanding the relationship between animal densities and plant distribution and abundance is essential for the conservation of endangered species and ecosystems. Mountain gorilla censuses conducted for different periods in the last three decades have revealed a steady increase of gorilla population in Virunga Massif whereby the recent number of gorillas has doubled compared to their number in the 1980s. It is unclear whether the continuous population growth of the herbivorous Virunga gorilla within an isolated forest ‘island’ has been affecting gorilla food plant biomass. This study investigated the effect of varying mountain gorilla densities on the biomass of the five key food plant species (Galium spp., Carduus nyassanus, Peucedanum linderi, Rubus spp., Laportea alatipes) that make up >70% of the mountain gorilla diet. We used plant biomass data collected in a central part of the Virunga massif, commonly known as Karisoke sector from 2009 to 2011, and GPS records of gorilla groups ranging in the same area nine months prior biomass assessment. Gorilla densities were estimated using the Kernel Utilization Distribution (KDE) analysis (functions: ‘kernelUD’ and ‘getvolumeUD’) from the Adehabitat package in R software, which provides the probability density of gorilla occurrence at each coordinate (x, y) of the study area. Analyses using GLMs suggest that gorilla densities (a proxy of previous gorilla utilization intensity) did neither affect the total biomass of key food plant species nor the biomass of each key food plant species (p>0.05). These results may indicate that current revisit rates of feeding sites by gorillas allow for complete plant regeneration, and no signs of overharvesting. Alternatively, feeding sites characterized by very high biomass may be preferred by gorillas and remain sites with the highest biomass even after being frequently used by gorillas. Findings also suggest that carrying capacity of the gorilla population in the study areas may not yet be reached if food is the driving constraint. However, monitoring of the relationship between gorilla densities and food plant biomass must continue while the Virunga population continues growing. Future studies also need to incorporate other sympatric large herbivores in the Virungas who share food plants with mountain gorillas.Keywords: habitat use, gorilla density, plants biomass

A Whole Systems Approach to Hospital Waste Management in Rural Uganda.

Introduction: Safe waste management protects hospital staff, the public, and the local environment. The handling of hospital waste in Bwindi Community Hospital did not appear to conform to the hospital waste management plan, exhibiting poor waste segregation, transportation, storage, and disposal which could lead to environmental and occupational risks.Methods: We undertook a mixed-methods study. We used semi-structured interviews to assess the awareness of clinical and non-clinical staff of waste types, risks, good practice, and concerns about hospital waste management. We quantified waste production by five departments for 1 month. We assessed the standard of practice in segregation, onsite transportation, use of personal protective equipment, onsite storage of solid waste, and disposal of compostable waste and chemicals.Results: Clinical staff had good awareness of waste (types, risk) overall, but the knowledge of non-clinical staff was much poorer. There was a general lack of insight into correct personal or departmental practice, resulting in incorrect segregation of clinical and compostable waste at source (>93% of time), and incorrect onsite transportation (94% of time). In 1 month the five departments produced 5,398 kg of hazardous and non-hazardous waste (12; 88%, respectively). Good practice included the correct use of sharps and vial boxes and keeping the clinical area clear of litter (90% of the time); placentae buried immediately (>80% of the time); gloves were worn everyday by waste handlers, but correct heavy-duty gloves <33% of the time, reflecting the variable use of other personal protective equipment. Chemical waste drained to underground soakaways, but tracking further disposal was not possible. Correct segregation of clinical and compostable waste at source, and correct onsite transportation, only occurred 6% of the time.Conclusion: Waste management was generally below the required WHO standards. This exposes people and the wider environment, including the nearby world heritage site, home to the endangered mountain gorilla, to unnecessary risks. It is likely that the same is true in similar situations elsewhere. Precautions, protection, and dynamic policy making should be prioritized in these hospital settings and developing countries.

Index hopping on the Illumina HiseqX platform and its consequences for ancient DNA studies.

The high-throughput capacities of the Illumina sequencing platforms and the possibility to label samples individually have encouraged wide use of sample multiplexing. However, this practice results in read misassignment (usually <1%) across samples sequenced on the same lane. Alarmingly high rates of read misassignment of up to 10% were reported for lllumina sequencing machines with exclusion amplification chemistry. This may make use of these platforms prohibitive, particularly in studies that rely on low-quantity and low-quality samples, such as historical and archaeological specimens. Here, we use barcodes, short sequences that are ligated to both ends of the DNA insert, to directly quantify the rate of index hopping in 100-year old museum-preserved gorilla (Gorilla beringei) samples. Correcting for multiple sources of noise, we identify on average 0.470% of reads containing a hopped index. We show that sample-specific quantity of misassigned reads depends on the number of reads that any given sample contributes to the total sequencing pool, so that samples with few sequenced reads receive the greatest proportion of misassigned reads. This particularly affects ancient DNA samples, as these frequently differ in their DNA quantity and endogenous content. Through simulations we show that even low rates of index hopping, as reported here, can lead to biases in ancient DNA studies when multiplexing samples with vastly different quantities of endogenous material.