Primate Population Density Research Articles

Identification and Population Density of Primate Animals in the Stik Jantho Aceh Besar Educational Forest

Long tail macac (Macac fascicularis) and black langur (Trachypitecus auratus) are two species of primates protected by law. The conservation status of both is listed as vulnerable in the IUCN and appendix II status in CITES. The very sharp population decline in the monkey population is due to declining habitat quality and poaching. The STIK educational forest is a secondary forest, which is disturbed by illegal logging and forest fires. The vegetation that forms the habitat for the lives of kedih and black langur primates in this area is not yet known. There is no data on primates from the kedih and langur groups in the STIK Jantho educational forest. This is the reason why this research is important to be conducted. The purpose of this study was to obtain data on monkeyand black langurs including the number of groups, the number of species, age structure and sex ratio in the STIK Jantho educational forest. Data collection in this study used the transex path method by recording the number of groups, the number of individuals, age structure and sex ratio. Data analysis using Arch GIS 10.1 to determine the distribution of monkey and black langur by plotting each coordinate obtained, using GPS visualized in the form of a map. Determination of the density of kedih and black langur using the formula: P = D x A. Found 2 types of primate animals (Trachypitecus auratus and Macaca fascicularis), each 1 group. The number of Trachyipitecus auratus individuals 10 individuals and Macaca fascicularis 50 individuals. Both species of primate animals are included in the developing age structure and have a complete composition (adult males and females, infant and juveneel. The results are presented in the form of a distribution map of black langur groups, and the population density of kedih and black langur primates, narrated in the form of a research reporthis document.

Analysis Of The Edge Effect On Bird And Primate Distribution In The Ecological Corridor Habitat Of Mount Halimun Salak National Park (TNGHS)

This study aims to analyze the threat of edge effects on endemic animal populations due to the presence of causeways in the TNGHS corridor habitat. Indicators of the occurrence of edge effects are characterized by the further distance of wildlife populations from sources of disturbance such as noise, light, and frequency of human activity mechanisms. Belt transect research method for population study and distribution of Javan Gibbon and Surili. Intensive Point Account (IPA) to measure the diversity index of bird species and Javan eagles. Encounter Rate is used for animal distribution studies. Results On the observation transect made along 3 km, the population density of Javan Gibbons was obtained 0.114 ind/ha, Surili 0.024 indv/ha, and Monkey 0.028 indv/ha. Bird species diversity index in 3 habitat patches each Purasari H'= 2.78 with 38 species; Garehong with 27 species, and Corridor H'= 3,087 with 27 species. The similarity of species is that there are only 7 species of birds found in the 3 habitats of the patch. As a result of primate population density and burng species similarity, it can be concluded that the cross-corridor access road area has experienced an edge effect and tends to be a bottle-neck area for the distribution of animals, especially primates.

Population size and habitat preference of the Omo River guereza (Colobus guereza guereza) in a multi-habitat matrix in the central highlands of Ethiopia.

Given the current rate of habitat degradation and loss in the tropics, data on primate population densities and habitat use are indispensable for assessing conservation status and designing feasible management plans for primates. The Omo River guereza (Colobus guereza guereza) is a subspecies of the eastern black-and-white colobus monkey endemic to the western Rift Valley forests of Ethiopia. Their restricted distribution along with habitat loss and hunting within their range render them vulnerable to local extirpation and extinction. Furthermore, there are no published data available on the population status and habitat use patterns of the Omo River guereza. We therefore aimed to assess the population size of Omo River guerezas in different habitats (Erica-Juniperus mixed forest, mixed plantation forest, undisturbed natural forest, disturbed natural forest) using transect surveys at Wof-Washa Natural State Forest (WWNSF) in central Ethiopia. Our surveys covered a cumulative distance of 88.5km in four different habitats, during which we recorded a total of 140 Omo River guereza groups. The average group density was 14.3 groups/km2, average individual density was 94.4 individuals/km2, and we estimated the total population size within WWNSF to be 2549 individuals. The sex ratio of the population was split evenly between males and females, though the age classes skewed strongly towards adults. Of the habitats surveyed, the highest group encounter rate (1.83 groups/km) occurred in the disturbed natural forest. However, the highest individual density (110.1 individuals/km2) was recorded in undisturbed natural forest. Still, sizable densities (group and individual) were recorded in three of the disturbed habitats (disturbed natural forest, mixed plantation forest, and to a lesser extent Erica-Juniperus mixed forest). Our study offers the first baseline information with which to compare future population density estimates and habitat use in the range of Omo River guerezas.

Distribution, population density and conservation of the critically endangered brown spider monkey (Ateles hybridus) and other primates of the inter-Andean forests of Colombia

The inter-Andean tropical rainforests and dry forests of the Magdalena river basin (Tumbes-Choco-Magdalena biodiversity hotspot) in northern Colombia have undergone significant forest loss and degradation in recent decades. Six primate species inhabit this region, five of which are currently threatened with extinction and one of which—the brown spider monkey, Ateles hybridus—is considered critically endangered. Accurate and recent information on the distribution and conservation status of these threatened primate populations is scarce or nonexistent, even though such data are needed to implement successful conservation actions and management plans. Between 2006 and 2016, we evaluated the status and distribution of primates across inter-Andean lowland forests in northern Colombia. We visited 30 sites to evaluate the presence/absence of brown spider monkeys and other primate taxa in the region. We also carried out surveys at 10 of these sites to obtain estimates of primate population densities and demographic information from forests with different levels of anthropogenic disturbance. Novel data on primate presence/absence were obtained for 27 sites, and 136 records were collected in total. Only 33% of the sites visited were large forest fragments (> 500 Ha). This study confirms that at least six primate species are still present in the Rio Magdalena region, which represents the highest platyrrhine diversity west of the Andes. This study also confirms the persistence of a wild population of Colombian woolly monkeys (Lagothrix lagotricha lugens) in the Serrania de San Lucas. Assigning formal protected status to this region is an urgent priority for the conservation of primates in the Rio Magdalena region.

Spatial Patterns of Primate Electrocutions in Diani, Kenya

Electrocution from power infrastructure threatens many primate species, yet knowledge of effective evidence-based mitigation strategies is limited. Mitigation planning requires an understanding of the spatial distribution of electrocutions to prioritize high-risk areas. In Diani, a coastal Kenyan town, electrocution is an important cause of death for five primate species. In this study we aim to describe the spatial patterns of electrocutions and electric shock incidents (collectively referred to as electrocutions hereafter) and identify electrocution hotspots to guide an effective primate conservation approach in Diani. Colobus Conservation, a not-for-profit organization, has recorded electrocutions and annual primate census data since 1998. We georeferenced 329 electrocution data points and analyzed them using QGIS. We identified and compared hotspots across species, seasons, and time using kernel density estimation and Getis-Ord-Gi*. We employed spatial regression models to test whether primate population density and power line density predicted the location of electrocution hotspots. Electrocutions occurred in hotspots that showed little variation in location between species and seasons. The limited variation in hotspot location over time likely occurred as a result of new building development in Diani and variability in primate detection rates by community members. Primate density and power line density were significant predictors of electrocution density for Angolan black-and-white colobus (Colobus angolensis palliatus) and Sykes monkeys (Cercopithecus mitis albogularis), but the relationship was weak, suggesting the presence of additional risk factors. This study provides a framework for systematic spatial prioritization of power lines that can be used to reduce primate electrocutions in Diani, and can be adopted in other areas of the world where primates are at risk from electrocution.

Landscape attributes as drivers of the geographical variation in density of Sapajus nigritus Kerr, 1792, a primate endemic to the Atlantic Forest

Neotropical primates are among the most well studied forest mammals concerning their population densities. However, few studies have evaluated the factors that influence the spatial variation in the population density of primates, which limits the possibility of inferences towards this animal group, especially at the landscape-level. Here, we compiled density data of Sapajus nigritus from 21 forest patches of the Brazilian Atlantic Forest. We tested the effects of climatic variables (temperature, precipitation), landscape attributes (number of patches, mean inter-patch isolation distance, matrix modification index) and patch size on the population density using linear models and the Akaike information criterion. Our findings showed that the density of S. nigritus is influenced by landscape attributes, particularly by fragmentation and matrix modification. Overall, moderately fragmented landscapes and those surrounded by matrices with intermediate indexes of temporal modification (i.e., crop plantations, forestry) are related to high densities of this species. These results support the assumptions that ecologically flexible species respond positively to forest fragmentation. However, the non-linear relationship between S. nigritus density and number of patches suggests that even the species that are most tolerant to forest cover changes seem to respond positively only at an intermediate level of habitat fragmentation, being dependent of both a moderate degree of forest cover and a high quality matrix. The results we found here can be a common response to fragmentation for those forest dweller species that are able to use the matrix as complementary foraging sites.

Estimating primate population densities: the systematic use of playbacks along transects in population surveys.

Accurate measures of animal population densities are essential to assess their status, demography, and answer ecological questions. Among several methods proposed to collect abundance data, line transect sampling is used the most. The assumptions required to obtain accurate density estimates through this method, however, are rarely met when studying primates. As most primate species are vocally active, density estimates can be improved by associating transect sampling with playback point counts to scan the entire study area. Yet, attention to playback procedure and data collection design is necessary. Here, we describe a protocol to assess primate densities using playback and test its application on surveys of Callicebus nigrifrons, a small Neotropical primate that shows site fidelity and active vocal behavior. We list important steps and discuss precautions that should be considered, from the adjustments in the recordings in the lab to field procedures in the playback broadcasting sessions. Prior to the surveys, we conducted playback trials with three habituated wild groups at three forest remnants to test their response to the playback stimuli at different distances. Based on these trials, we defined the radius distance covered by the playback sessions. Then, we conducted two surveys in 12 forest remnants, in the northeast of São Paulo State Brazil. The results of density estimates were consistent between the two surveys. As the playback survey protocol we described has proved to be a simple and useful tool for surveying vocal primate and generated reliable data, we suggest that it is a good alternative method to estimate density of species, particularly for those that are responsive to playbacks and show site fidelity.

Nutritional Differences between Two Orangutan Habitats: Implications for Population Density.

Bottom-up regulatory factors have been proposed to exert a strong influence on mammalian population density. Studies relating habitat quality to population density have typically made comparisons among distant species or communities without considering variation in food quality among localities. We compared dietary nutritional quality of two Bornean orangutan populations with differing population densities in peatland habitats, Tuanan and Sabangau, separated by 63 km. We hypothesized that because Tuanan is alluvial, the plant species included in the orangutan diet would be of higher nutritional quality compared to Sabangau, resulting in higher daily caloric intake in Tuanan. We also predicted that forest productivity would be greater in Tuanan compared to Sabangau. In support of these hypotheses, the overall quality of the diet and the quality of matched dietary items were higher in Tuanan, resulting in higher daily caloric intake compared to Sabangau. These differences in dietary nutritional quality may provide insights into why orangutan population density is almost two times greater in Tuanan compared to Sabangau, in agreement with a potentially important influence of diet quality on primate population density.

Bioenergetic Constraints on Primate Abundance

Explaining variation in primate population densities is central to understanding primate ecology, evolution, and conservation. Yet no researchers to date have successfully explained variation in primate population density across dietary class and phylogeny. Most previous work has focused on measures of food availability, as access to food energy likely constrains the number of individuals supported in a given area. However, energy output may provide a measure of energy constraints on population density that does not require detailed data on food availability for a given taxon. Across mammals, many studies have shown that population densities generally scale with body mass−0.75. Because individual energy expenditures scale with body mass0.75, population energy use (the product of population density and individual energy use) does not change with body mass, which suggests the existence of energy constraints on population density across body sizes, i.e., taxa are limited to a given amount of energy use, constraining larger taxa to lower densities. We examined population energy use and individual energy expenditure in primates and tested this energy equivalence across body mass. We also used a residual analysis to remove the effects of body mass on primate population densities and energy expenditures using basal metabolic rates (BMR; kcal/d) as a proxy for total daily energy expenditure. After taking into account phylogeny, population energy use did not significantly correlate with body mass. Larger primates, which use more energy per day, live at lower population densities than smaller primates. In addition, we found a significant negative correlation between residuals of BMR from body mass and residuals of population density from body mass after taking phylogeny into account. Thus, energy costs constrain population density across a diverse sample of primates at a given body mass, and primate species that have relatively low BMRs exist at relatively high densities. A better understanding of the determinants of primate energy costs across geography and phylogeny will ultimately help us explain and predict primate population densities.

Thirty Years of Research in Kibale National Park, Uganda, Reveals a Complex Picture for Conservation

Kibale National Park, Uganda, has a rich and abundant primate community and a complicated history of anthropogenic disturbance. Moreover, it has been the focus of over 30 yr of research and has received considerable attention from nongovernmental and governmental conservation organizations. As a result, Kibale serves as a valuable case study with which to evaluate the factors that regulate primate population density and the challenges of deriving generalizations for conservation. We review the impact of logging and forest fragmentation on primate population density and trace the efficacy of various conservation strategies. A 28-yr comparison of primate abundance in logged and unlogged forests and a 10-yr study of forest dynamics showed that primate recovery in logged areas is generally slow or not occurring at all for some species, which is likely driven by the fact that the forest is not recovering as expected. No primate species characteristic predicted their ability to live in forest fragments around Kibale. While a nutritional model was useful to predict the abundance of colobus in forest fragments outside of Kibale, a 5-yr study revealed that human land-use practices are more fundamentally shaping population dynamics. We evaluate data on primate abundance in light of Milton’s protein/fiber model to predict colobine biomass. We demonstrate that while the model can predict colobus biomass in pristine habitats, the 2 colobus species respond differently to disturbance. We offer suggestions for future conservation research and consider strategies to conserve forested national parks based on experiences gained over 30 yr.

Primate Population Densities in Three Nutrient-Poor Amazonian Terra Firme Forests of South-Eastern Colombia

We censused primate populations at three non-hunted ‘terra firme’ forests of south-eastern Colombian Amazonia. The aggregate biomass densities of diurnal primates at all sites were amongst the lowest recorded for any non-hunted forest in western Amazonia and elsewhere in the Neotropics. Densities of red howler monkeys were low, as is typical in Amazonian terra firme forests far removed from white-water rivers, and densities of woolly monkeys were 1.5–3.5 times lower than those estimated for this species in central-western Brazilian Amazonia. Densities of small to mid-sized primates except for brown capuchins (Cebus apella) and white-faced capuchins (Cebus albifrons) were similar to those of other oligotrophic Amazonian forest sites. Our results are in agreement with other studies showing that terra firme forests of lowland Amazonia typically sustain a low biomass density of primates and other mid-sized to large vertebrates. Large reserves are therefore required to assure the viability of primate populations in oligotrophic systems. Given the escalating negative impacts of human habitat disturbance and hunting in Colombian Amazonia, we urge that a baseline sampling protocol to quantify the abundance and distribution of the harvest-sensitive vertebrate fauna be established within protected areas and the large indigenous reserves so that conservation efforts can be defined and implemented.

Population density of primates in a large fragment of the Brazilian Atlantic rainforest

We performed a line transect survey (352.4 km) of primates in the Serra de Paranapiacaba, at one of the largest relatively undisturbed fragments of the Atlantic rainforest of Southeastern Brazil (ca. 1400 km2), in August 1998. The brown capuchin, Cebus apella nigritus, was the most common species found in the area (20 groups, density estimate: 5.31 ± 2.05 individuals per km2, mean ± SE). Nine groups of the brown howler monkey, Alouatta guariba clamitans, and eight of the woolly spider monkey, Brachyteles arachnoides arachnoides, were also recorded, with preliminary density estimates of 0.79 ± 0.40 and 2.33 ± 1.37 individuals per km2, respectively. Density estimates for these species in other fragments of Atlantic rainforest are reviewed, showing that densities in Paranapiacaba are among the lowest reported. It is suggested that the higher densities reported for isolated populations in small forest patches (<50 km2) is related to the absence of main primate predators, the density compensation phenomenon and the ecological plasticity of some primate species. In contrast, local extinction in many small patches is probably related to hunting pressure. Given the important primate populations found in the Paranapiacaba fragment, conservation strategies for the studied species should give priority to effective protection of the largest remnant fragments from illegal hunting and deforestation, rather than translocation of individuals or captive breeding programs to introduce monkeys in small forest fragments vulnerable to hunting and of uncertain future.

Primate Population Densities and Sizes in Atlantic Forest Remnants of Northern Espírito Santo, Brazil

We surveyed primates in seven fragments of Atlantic forest ranging from 210 to 24,250 ha in Espirito Santo, southeastern Brazil. The objective was to assess their population densities and fragment-specific population sizes in order to discuss the survival of primates in this highly fragmented landscape. We used line-transect sampling for censusing primates and estimated densities via DISTANCE program. Alouatta fusca, Cebus apella, Callicebus personatus, and Callithrix geoffroyi live in the study area. Although variable, primate numbers were higher in larger than in smaller fragments, the likely reasons being the lack of space and food resources (fruits) and higher impact of mesopredators (small cats) in small fragments. The estimated densities are within the range reported for other Atlantic forest sites, except for brown howlers (Alouatta fusca), which were extremely rare. Estimates of population sizes were on the order of several hundreds to thousands of individuals/species in the large-sized fragments (ca. 20,000 ha), while comparable estimates for the other areas indicate <500 individuals/species in the medium-sized reserves (ca. 2,000 ha), and <50 individuals/species in the small fragments (ca. 200 ha). These estimates suggest that only Atlantic forest fragments ≥20,000 ha can harbor primate populations large enough to escape extinction in the long term. Given that <20% of all protected areas remaining in the Atlantic forest are ≥20,000 ha, management measures are urgently needed to improve primate conservation in this biome.

Effects of habitat disturbance on the behavioral ecology and demographics of the Tana river red colobus (Colobus badius rufomitratus)

Annual surveys in 1985–1987 revealed that, since 1975, the total population of the Tana River red colobus (Colobus badius rufomitratus)declined by approximately 80%. An intensive study in 1986–1988 of two groups of colobus in the Tana River Primate National Reserve indicated that habitat disturbance from the changing river course and shifting agricultural practices were primarily responsible for the decline. Clearcutting around Mchelelo forest in the late 1960s compressed colobus populations to levels probably above the carrying capacity. Between 1975 and 1986 primate population density declined dramatically, the number of red colobus groups in Mchelelo forest decreased by half, and the size of the remaining group was greatly reduced. In 1986, there were fewer solitary colobus and small parties in the forest, harem male takeovers did not occur, infant survivorship increased, and demographic parameters generally had improved. The colobus groups in Mchelelo in 1973–1975, living at higher densities, showed different feeding and ranging behaviors than 1986–1988 groups. Range size was smaller in 1975, range overlap occurred, and a greater portion of the forest was used per day and per month. Mature leaves accounted for a much higher proportion of the diet. Time spent feeding and resting was the same in both studies. Social organization in predominantly one- male groups was maintained and adult and subadult females transferred between groups.

Determinants of Variation in Tropical Forest Primate Biomass: New Evidence from West Africa

To explore sources of variation in tropical forest primate biomass, and, in particular, to test the hypothesis that soil conditions are a major ultimate determinant of the biomass of colobine monkeys and other primates, we compared data on the soils, vegetation, and primate community at a site in West Africa (Tiwai Island, Sierra Leone) with information from other sites, especially two other African sites (Douala—Edea in Cameroon, and Kibale Forest in Uganda). The biomass of eight anthropoid primate species in old secondary high forest on Tiwai was estimated from data on population densities assessed by transect samples combined with data on social group densities and individual body masses. Samples of soil and tree foliage were collected at the same site, and subjected to a variety of chemical and mechanical analyses. Our estimate of anthropoid biomass at Tiwai is 1229—1529 kg/km2, including 682—889 kg/km2 of colobines. This is one of the highest primate biomasses recorded anywhere. The soils at Tiwai were found to be relatively high in sand content and low in pH, and to have low levels of mineral nutrients. Levels of condensed tannins in the mature foliage of the trees comprising a major part of the forest canopy were higher than at other sites, but the ratio of protein to fiber in this foliage was also higher than at any other site except Kibale. It is argued that a wide range of environmental factors affect primate population densities, and that nutrient—poor soils and high tannin levels in tree foliage do not necessarily produce a low primate (or colobine) biomass, as some earlier studies had suggested. Furthermore, seeds (an important food source for Tiwai colobines) are apparently a common part of the colobine dietary repertoire and are not consumed largely as a response to a scarcity of digestible foliage.