Terrestrial Herbaceous Vegetation Research Articles

A Test of Foraging Models Using Dietary Diversity Indices for the Lomako Forest Bonobos

Optimal diet and functional response models are used to understand the evolution of primate foraging strategies. The predictions of these models can be tested by examining the geographic and seasonal variation in dietary diversity. Dietary diversity is a useful tool that allows dietary comparisons across differing sampling locations and time periods. Bonobos (Pan paniscus) are considered primarily frugivorous and consume fruits, leaves, insects, vertebrates, terrestrial herbaceous vegetation, and flowers. Frugivores, like bonobos, are valuable for examining dietary diversity and testing foraging models because they eat a variety of species and are subject to seasonal shifts in fruit availability. Frugivorous primate species thus allow for tests of how variation in dietary diversity is correlated with variation in ecological factors. We investigated measures of dietary diversity in bonobos at two research camps across field seasons within the same protected area (N’dele and Iyema) in Lomako Forest, Democratic Republic of the Congo. We compared the results of behavioral observation (1984/1985, 1991, 1995, 2014, and 2017) and fecal washing analysis (2007 and 2009) between seasons and study period using three diversity indices (Shannon’s, Simpson’s, and SW evenness). The average yearly dietary diversity indices at N’dele were Shannon’s Hʹ = 2.04, Simpson’s D = 0.82, and SW evenness = 0.88 while at Iyema, the indices were Shannon’s Hʹ = 2.02, Simpson’s D = 0.82, and SW evenness = 0.88. Behavioral observation data sets yielded significantly higher dietary diversity indices than fecal washing data sets. We found that food item (fruit, leaf, and flower) consumption was not associated with seasonal food availability for the 2017 behavioral observation data set. Shannon’s index was lower during periods when fewer bonobo dietary items were available to consume and higher when fruit was abundant. Finally, we found that optimal diet models best-explained patterns of seasonal food availability and dietary diversity. Dietary diversity is an essential factor to consider when understanding primate diets and can be a tool in understanding variation in primate diets, particularly among frugivores. Dietary diversity varies across populations of the same species and across time, and it is critical in establishing a complete understanding of how primate diets change over time.

Chimpanzee feeding ecology and fallback food use in the montane forest of Nyungwe National Park, Rwanda.

Almost all primates experience seasonal fluctuations in the availability of key food sources. However, the degree to which this fluctuation impacts foraging behavior varies considerably. Eastern chimpanzees (Pan troglodytes schweinfurthii) in Nyungwe National Park, Rwanda, live in a montane forest environment characterized by lower primary productivity and resource diversity than low-elevation forests. Little is known about chimpanzee feeding ecology in montane forests, and research to date predominantly relies on indirect methods such as fecal analyses. This study is the first to use mostly observational data to examine how seasonal food availability impacts the feeding ecology of montane forest chimpanzees. We examine seasonal changes in chimpanzee diet and fallback foods (FBFs) using instantaneous scan samples and fecal analyses, supported by inspection of feeding remains. Chimpanzee fruit abundance peaked during the major dry season, with a consequent change in chimpanzee diet reflecting the abundance and diversity of key fruit species. Terrestrial herbaceous vegetation was consumed throughout the year and is defined as a "filler" FBF. In contrast to studies conducted in lower-elevation chimpanzee sites, figs (especially Ficus lutea) were preferred resources, flowers were consumed at seasonally high rates and the proportion of non-fig fruits in the diet were relatively low in the current study. These divergences likely result from the comparatively low environmental diversity and productivity in higher-elevation environments.

Bonobos' saliva remaining on the pith of terrestrial herbaceous vegetation can serve as non-invasive wild genetic resources.

Evaluating the genetic diversity of natural populations of endangered species is important for conservation. Although the genetic analysis of wildlife usually requires collecting DNA non-invasively, the variety of non-invasive DNA sampling methods is limited for each species. We present a method to obtain DNA of an endangered species, the bonobo (Pan paniscus), in which the pith of the terrestrial herbaceous vegetation (THV) that they consumed was newly utilized. We investigated the (1) frequency of encountering remnant saliva on three types of THV pith; (2) concentrations of DNA in the saliva samples by the real-time quantitative PCR; and (3) rates of positive PCR, accurate genotyping, and allelic drop out by analyzing two autosomal microsatellite loci (D7s817 and D9s910). The number of remnant saliva samples was recorded by following the bonobo groups on a daily basis. The frequency of encountering DNA samples was higher in saliva samples than in fecal samples. More than half of the saliva samples remaining on two types of THV pith provided sufficient concentrations of bonobo DNA (> 200pg/μl). Rates of positive PCR and accurate genotyping were high, and allelic drop out rate was low when the amount of template DNA was above 200pg per reaction. Our results suggest that the remnants of bonobo saliva on the pith of THV are a potential resource for obtaining DNA, and better than other kinds of samples from the perspective of the abundant sampling opportunities.

African apes coexisting with logging: Comparing chimpanzee (Pan troglodytes troglodytes) and gorilla (Gorilla gorilla gorilla) resource needs and responses to forestry activities

The extraction of timber often conflicts with the well-being and conservation of wildlife. In particular, there is a need to better understand the impact of tree removal under selective logging regimes on local ecological communities. We conducted ape nest counts along line transects before, during, and after logging to assess the impact of timber harvesting and associated activities on sympatric chimpanzees and gorillas in a forestry concession in northern Republic of Congo. We used generalized linear models to relate ape nest counts to a set of predictor variables, representing the impact of logging and controlled for variation in environmental conditions including food availability, habitat and rainfall. Commercial forest inventory data were used to assess the baseline influence of food availability and forest structure on ape distribution. Higher numbers of chimpanzees were found in proximity to their preferred tree foods, whereas gorillas were associated with more heterogeneous habitats. Chimpanzee nest encounter rates decreased with increasing intensity of human impacts. Gorillas also avoided areas with active timber exploitation and roads, but were attracted to recently logged areas with abundant terrestrial herbaceous vegetation. Species-specific responses were consistent with theoretical predictions of niche partitioning and cumulative human influence. Based on these findings, we provide recommendations to improve existing guidelines and forest certification standards aimed at safeguarding ape populations.

Bonobo nest site selection and the importance of predictor scales in primate ecology.

The role of spatial scale in ecological pattern formation such as the geographical distribution of species has been a major theme in research for decades. Much progress has been made on identifying spatial scales of habitat influence on species distribution. Generally, the effect of a predictor variable on a response is evaluated over multiple, discrete spatial scales to identify an optimal scale of influence. However, the idea to identify one optimal scale of predictor influence is misleading. Species-environment relationships across scales are usually sigmoid increasing or decreasing rather than humped-shaped, because environmental conditions are generally highly autocorrelated. Here, we use nest count data on bonobos (Pan paniscus) to build distribution models which simultaneously evaluate the influence of several predictors at multiple spatial scales. More specifically, we used forest structure, availability of fruit trees and terrestrial herbaceous vegetation (THV) to reflect environmental constraints on bonobo ranging, feeding and nesting behaviour, respectively. A large number of models fitted the data equally well and revealed sigmoidal shapes for bonobo-environment relationships across scales. The influence of forest structure increased with distance and became particularly important, when including a neighbourhood of at least 750 m around observation points; for fruit availability and THV, predictor influence decreased with increasing distance and was mainly influential below 600 and 300 m, respectively. There was almost no difference in model fit, when weighing predictor values within the extraction neighbourhood by distance compared to simply taking the arithmetic mean of predictor values. The spatial scale models provide information on bonobo nesting preferences and are useful for the understanding of bonobo ecology and conservation, such as in the context of mitigating the impact of logging. The proposed approach is flexible and easily applicable to a wide range of species, response and predictor variables and over diverse spatial scales and ecological settings.

Floristic and structural vegetation typology of bonobo habitats in a forest-savanna mosaic (Bolobo Territory, D.R.Congo)

Background and aims – Forest-savanna mosaics are some of the very diverse habitat types of the Congo Basin; multiple factors influence their dynamics such as climatic and edaphic conditions, animal dispersion, and anthropogenic activities. Presently, few studies have described this type of habitat, despite their important role in biodiversity conservation and their fragmentation. This study identified and described the floristic and structural composition of eight vegetation types of a long-term study site for bonobos in a forest-savanna mosaic of Bolobo Territory in the southwestern Congo Basin, Democratic Republic of the Congo (DRC). Methods – We surveyed trees, lianas and terrestrial herbaceous vegetation in 51 sampling units using a nested plot sampling, totaling 12.75 ha for trees with diameter at breast height (1.30 m above ground level, dbh) ≥ 30 cm, 5.1 ha for tree species with 10 cm ≤ dbh < 30 cm, and 0.02 ha for herbaceous vegetation, seedlings and saplings. First, detrended correspondence analysis of floristic data allowed the discrimination of seasonally inundated forests from terra firma forests. Then, structural data were analyzed to discriminate five terra firma forest types using hierarchical cluster analysis. Key results – In this survey, 146 trees, 50 lianas and 42 herbaceous species were identified. Eight vegetation types were characterized. Each vegetation type was described in terms of structure (trees and lianas densities, basal areas, herbaceous vegetation densities) and floristic characteristics (species diversity, importance value index of tree species). Conclusions – Some characteristics of vegetation types were particularly relevant to discuss (1) the forest-savanna dynamics and the important role of Pentaclethra eetveldeana in the plant succession, and (2) the effects of anthropogenic activities on different vegetation types

Estrutura da vegetação herbácea em paisagens ciliares no sul de Santa Catarina, Brasil

As características estruturais e ecológicas da vegetação herbácea fazem com que ela seja sensível às alterações do ambiente, atuando como indicador da qualidade ambiental. No entanto, o estudo dessa comunidade ainda é incipiente em regiões neotropicais. Este estudo descreve a florística e os aspectos fitossociológicos da vegetação herbácea terrícola na mata ciliar de sete rios, no município de Urussanga, sul do estado de Santa Catarina, além de analisar e quantificar o status do conhecimento científico relacionado às herbáceas terrícolas no Brasil. Foram levantadas 320 unidades amostrais de 4 m², nas quais todos os indivíduos foram identificados e dados relacionados aos parâmetros fitossociológicos foram coletados. A amostragem resultou em 58 táxons, 38 pertencentes às angiospermas e 20 às samambaias, distribuídos em 25 famílias botânicas. Poaceae apresentou maior riqueza, com 11 espécies. Estruturalmente, destacaram-se Goeppertia monophylla (Vell.) Borchs. e S. Suárez, Blechnum brasiliense Desv. e Heliconia farinosa Raddi. A forma de vida mais frequente foi a hemicriptófita reptante. Os resultados revelam uma elevada riqueza de herbáceas terrícolas adaptadas às condições climáticas das matas ciliares, contribuindo para a diversidade da flora regional. Quanto à produção científica, foram encontrados 50 trabalhos indexados nas bases de dados eletrônicas (1990 a 2015), com destaque ao ano de 2011, que teve maior produção científica enfocando as herbáceas terrícolas. Embora com baixo número, a quantidade de indexações tende a crescer, em virtude do avanço da tecnologia de acesso às bases de dados e pela crescente adesão de periódicos em portais de busca.

Chimpanzees in an anthropogenic landscape: Examining food resources across habitat types at Bossou, Guinea, West Africa.

Many primate populations occur outside protected areas in fragmented anthropogenic landscapes. Empirical data on the ecological characteristics that define an anthropogenic landscape are urgently required if conservation initiatives in such environments are to succeed. The main objective of our study was to determine the composition and availability of chimpanzee (Pan troglodytes verus) food resources across fine spatial scales in the anthropogenic landscape of Bossou, Guinea, West Africa. We examined food resources in all habitat types available in the chimpanzees' core area. We surveyed resource composition, structure and heterogeneity (20 m × 20 m quadrats, N = 54) and assessed temporal availability of food from phenology trails (total distance 5951 m; 1073 individual trees) over 1 year (2012-2013). Over half of Bossou consists of regenerating forest and is highly diverse in terms of chimpanzee food species; large fruit bearing trees are rare and confined to primary and riverine forest. Moraceae (mulberries and figs) was the dominant family, trees of which produce drupaceous fruits favored by chimpanzees. The oil palm occurs at high densities throughout and is the only species found in all habitat types except primary forest. Our data suggest that the high densities of oil palm and fig trees, along with abundant terrestrial herbaceous vegetation and cultivars, are able to provide the chimpanzees with widely available resources, compensating for the scarcity of large fruit trees. A significant difference was found between habitat types in stem density/ha and basal area m2 /ha of chimpanzee food species. Secondary, young secondary, and primary forest emerged as the most important habitat types for availability of food tree species. Our study emphasizes the importance of examining ecological characteristics of an anthropogenic landscape as each available habitat type is unlikely to be equally important in terms of spatial and temporal availability of resources. Am. J. Primatol. 78:1237-1249, 2016. © 2016 Wiley Periodicals, Inc.

Chimpanzee non-avoidance of hyper-proximity to humans

A species, especially when it is endangered and surrounded by anthropogenic elements, can be threatened by habitat fragmentation. Food resource availability in the species’ usual or surrogate habitats may reinforce or decrease its use of certain areas. Our objective was to to determine the influence of natural and anthropogenic variables on spatial distribution of eastern chimpanzees (Pan troglodytes schweinfurthii). We first determined the home range of a wild chimpanzee community (hereafter Sebitoli Chimpanzee Community [SCC]) based on global positioning system (GPS) point locations (n¼2,586 direct observations and feces locations) collected between 2009 and 2013 in Sebitoli, Kibale National Park, Uganda. We described SCC home range using grid cells (2,959 cells of 100m100m) referencing environmental, spatial, and topographical variables (n¼15). We then determined diet and food species abundance within their territory (n¼63 vegetation plots and 18 months phenological survey) and predicted distribution of the 10 most foraged fruit species within SCC home range, using environmental, spatial, and topographical variables (n¼10) by applying a maximum entropy model (maxent). We then predicted chimpanzee presence as a function of environmental, spatial, and topographical variables (n¼15) using the maxent model and assessed its truthfulness with the kernel model, based only on GPS point locations. Chimpanzees in Sebitoli were mostly observed in a core area of 5.42 km2 within the 25-km2 home range. They did not avoid forest edges in contact with human populations, especially males who used larger core areas than females. Factors with the greatest positive impact on the chimpanzee distribution model (maxent area under the curve [AUC]¼0.907) were related to 3 different food resources: 1) proximity to forest edges considered as attractive because of presence of crops cultivated by local farmers; 2) proximity to a tarmac road that crosses the SCC home range with shoulders covered by attractive terrestrial herbaceous vegetation; and 3) presence of wild forest fruiting resources. The results obtained with the maxent predictive model, applied on a fine scale, were consistent with the kernel model, based on real observations. Therefore, such an approach may be recommended for surveys or action plans interested in sustainable management of wildlife in an anthropogenic environment and may be a useful tool to better understand parameters of a prefered zone for an endangered species.

Upper Eocene coal and coaly shale in the Central Myanmar Basin: Origin of organic matter and the effect of weathering

Extensive coals and coaly shales were deposited at the western margin of the Central Myanmar Basin (CMB) during the Late Eocene. Carbon, nitrogen and sulfur (CNS) elemental analyses, vitrinite reflectance, Rock-Eval pyrolysis, biomarker analyses and δ13C measurements were made of eight coal and coaly shale samples from the Pondaung and Yaw Formations. Moderate weathering was recognized in three coaly shales, as manifest by microscopic cracks, holes, and rim structures in vitrinite. A sample pair of fresh and weathered coaly shale collected from the same seam showed that HI, Pr/Ph ratio, and concentration of PAHs and long chain n-alkanes (>n-C20) bonded to kerogen in the coaly shales decreased drastically due to weathering, while OI increased. These results suggest that hydrocarbon generation potential of the coaly shale as an oil/gas source rock decreased to about one tenth by the weathering, whereas the free n-alkanes, biomarkers such as steranes and triterpanes, and δ13C ratios of kerogen were not affected. Facies change from the coaly shale layers (Phase-I) to the coal layers (Phase-II) was accompanied by variations in origin of the organic matter. The source of the organic matter was mainly terrestrial herbaceous vegetation and/or aquatic plants, deposited in oxic to oxygen-poor peat swamps associated with an estuarine/fluvial-deltaic setting. Phase-I is relatively rich in gymnosperm biomarkers such as retene and 1,7-dimethylphenanthrene (DMP), whereas Phase-II shows an increase in angiosperm proxies such as oleanane content and oleanane/C30 hopane ratio, with δ13C values ranging from -24.6‰ to -26.5‰. Based on HI values of unweathered samples, Phase-I is characterized by type II-III kerogen, while Phase-II contains type III kerogen. Higher values of HI, Pr/Ph ratios, n-C29/n-C19 alkane ratios (>1.5), and higher concentrations of conifer-derived 1,7-DMP in Phase-I suggest a significant contribution from material of resinous vascular plant origin. High Fluoranthene/(Fluoranthene+Pyrene) ratio in the uppermost coal suggests occurrence of wildfire, probably related to a dry climate experienced in Phase-II. Unweathered CMB samples show good source rock quality, with potential generation of liquid/gas hydrocarbons.

Ground Night Nesting in Chimpanzees: New Insights from Central Chimpanzees (Pan troglodytes troglodytes) in South-East Cameroon

Some chimpanzee populations exhibit ground night nesting, which occurs in different habitat types, is driven by a variety of interconnected factors, and may reflect cultural or social differences. This has important implications for ape conservation management, given that accurate nest builder identification is required to estimate density, crucial in monitoring, and allows inferences about environmental and social factors that may have contributed to the transition from tree to ground sleeping in early hominins. We conducted a 24-month marked nest count survey in La Belgique, Cameroon, and recorded the occurrence of chimpanzee tree and ground night nests, temperature and rainfall, predator and large mammal abundance, human activities, nesting tree species, and Uapaca spp. consumption. Ground night nesting occurred at a rate of 3.47% (n = 1,008), with more in swamps, in the dry season and with increasing human activities. We found no influence of leopard/elephant presence, but a possible influence of lack of nesting trees. We suggest chimpanzees visit swamps in the dry season (low water levels) for relief from hunting pressure and to consume Uapaca spp. fruits. Ground nesting may be enabled due to high abundance of terrestrial herbaceous vegetation, and may be favoured for inconspicuousness and safety from gun hunters.

Lesula: A New Species of Cercopithecus Monkey Endemic to the Democratic Republic of Congo and Implications for Conservation of Congo’s Central Basin

In June 2007, a previously undescribed monkey known locally as “lesula” was found in the forests of the middle Lomami Basin in central Democratic Republic of Congo (DRC). We describe this new species as Cercopithecus lomamiensis sp. nov., and provide data on its distribution, morphology, genetics, ecology and behavior. C. lomamiensis is restricted to the lowland rain forests of central DRC between the middle Lomami and the upper Tshuapa Rivers. Morphological and molecular data confirm that C. lomamiensis is distinct from its nearest congener, C. hamlyni, from which it is separated geographically by both the Congo (Lualaba) and the Lomami Rivers. C. lomamiensis, like C. hamlyni, is semi-terrestrial with a diet containing terrestrial herbaceous vegetation. The discovery of C. lomamiensis highlights the biogeographic significance and importance for conservation of central Congo’s interfluvial TL2 region, defined from the upper Tshuapa River through the Lomami Basin to the Congo (Lualaba) River. The TL2 region has been found to contain a high diversity of anthropoid primates including three forms, in addition to C. lomamiensis, that are endemic to the area. We recommend the common name, lesula, for this new species, as it is the vernacular name used over most of its known range.

Density of herbaceous plants and distribution of western gorillas in different habitat types in south‐east Cameroon

AbstractThe study of forest herb availability improves knowledge of ecology and conservation of gorillas that depend on such herbs. Density patterns of herbs and location of western gorilla nest sites were studied in different habitat types at a site in south‐east Cameroon to assess their relationship. Herb stems of the families Marantaceae and Zingiberaceae were identified and counted in 10,713 1‐m2 plots distributed within six habitat types. Stem density correlated with light availability and ranged from 2.38 stems m−² in near primary forest to 4.66 stems m−² in light gaps. Gorillas showed marked preferences for habitats with high herb densities such as light gaps, swamps and young secondary forest. However, no clear relationship exists between terrestrial herbaceous vegetation and gorilla densities across Central Africa. It is suggested that differences in ecological factors and land use history within and between sites may explain differences in herb density and diversity which partly account for variations in the historical and present population distribution and density of western gorillas. Formerly logged and swamp forests, which are characterized by an abundance of herbs, may prove to be of great value in the conservation of western gorillas given appropriate forest management practices, adequate protection from poaching and limited human encroachment.

Seed predation by bonobos (Pan paniscus) at Kokolopori, Democratic Republic of the Congo

We compared the feeding ecology of the Hali-Hali community of bonobos (Pan paniscus) at Kokolopori, a new field site in the Democratic Republic of the Congo, between two periods 5 months apart. During the first study period (SP1), bonobos relied heavily on the dry seeds of Guibourtia (Caesalpiniaceae), mostly eaten from the ground. The second period (SP2) was characterized by high consumption of ripe tree fruit. Terrestrial herbaceous vegetation (THV) contributed little to the diet in either study period. The low amount of ripe fruit and the high reliance on seeds in the diet during SP1 were associated with high cortisol production and low levels of urinary C-peptide in females, suggesting nutritional stress. However, female gregariousness was not constrained during the fruit-poor period, probably because high seed abundance on the ground ameliorated scramble feeding competition. This is the first description of extensive seed predation by bonobos. It suggests that bonobo feeding ecology may be more similar to that of chimpanzees than previously recognized.

Sympatric Chimpanzees (Pan troglodytes troglodytes) and Gorillas (Gorilla gorilla gorilla) in Loango National Park, Gabon: Dietary Composition, Seasonality, and Intersite Comparisons

Dietary overlap of sympatric apes is complex and understudied, but its examination is essential to further our understanding of species distribution, abundance, and community ecology. Over 3 yr we studied food availability and dietary composition of central chimpanzees (Pan troglodytes troglodytes) and western gorillas (Gorilla gorilla gorilla) in Loango National Park, Gabon. We predicted that living in a habitat dominated by mature forest with sparse terrestrial herbaceous vegetation would lead to an increase in frugivory by gorillas, resulting in increased dietary overlap between the 2 ape species vs. other sites, but that chimpanzees would remain more frugivorous than gorillas. Through fecal analysis we measured overlap in fruit consumption between the 2 species on a bimonthly basis using the Renkonens method. Mean overlap was 27.5% but varied greatly seasonally, ranging between 0.3% and 69%, indicating that when examined on a finer scale, the degree of overlap appears much lower than at other study sites. In contrast to studies elsewhere, there was not a positive correlation between rainfall and fruit availability in Loango, and the long dry season was a period of high fruit production. As observed elsewhere, we found a positive correlation between fruit consumption and fruit availability for both chimpanzees and gorillas and we found that chimpanzees were more frugivorous than gorillas. A very low availability of herbs did not lead to increased frugivory by gorillas nor increased overlap between the 2 ape species vs. other field sites. We conclude that forest composition, fruit availability, and dietary variability of sympatric species can vary greatly between locations, and that chimpanzees and gorillas can adapt to primary forest with little undergrowth, where they concentrate their diet on fruit and leaves.

Ecological changes in the highest temporary pond of western Crete (Greece): past, present and future

This study explores the past, present and future ecological changes in the highest Mediterranean temporary pond (Omalos pond) in western Crete, Greece. Data from downcore pollen analysis (including pollen and spores from both aquatic vegetation, and terrestrial herbaceous, arboreal and shrub vegetation), modern vegetation monitoring and existing climate scenarios have been combined to provide a picture of the ecological changes in the pond over the last 13,600 years. Downcore pollen analysis throughout the last 13,600 years indicated the presence of species typical of Mediterranean Temporary Pond (MTP) habitats and suggested relatively drier conditions towards the present. The low number of non-native, cultivated species (such as herbaceous Trifolium and Plantago species) observed over this period suggested relatively low impact from crop agriculture, despite the increasing grazing pressure in the area. In the absence of independent proxies, we cannot reliably distinguish between natural and human-induced changes. The presence of aquatic Isoetes in the palaeo-record indicates the existence of an ephemeral pond in the area as early as the beginning of the Holocene suggesting resilience of the ecosystem over time. However, the degraded state of pollen in depths over 55 cm (i.e. 3600 year BP) increases the uncertainty of the interpretation. Currently, the pond holds 76 plant species belonging to 25 families. Therophytes and chamaephytes were the most frequent, suggesting a typical ephemeral habitat life form spectrum. Species richness was found to increase during spring surveys whereas the highest turnover was observed between summer surveys of consecutive years. Cluster analysis demonstrated a distinct zonation in four vegetation belts from the periphery to the centre of the pond which is typical of these environments. Modelling, based on two IPPC scenarios (A2 and B2), predicted relatively low climate change impacts on the pond’s hydroperiod for the next 100 years (i.e. a decrease of 16 and 24 days, respectively). This reduction in the hydroperiod of the pond will have an effect on the physiognomy and spatial extent of vegetation, particularly for the transitional belts between the core and its outer area, while it will exert more pressure on the pond as a water resource for sheep in the region. However, cumulative effects and complex interactions of climate-driven environmental changes and other anthropogenic disturbances might act synergistically to accelerate impacts in the future.

Bonobo Food Items, Food Availability and Bonobo Distribution in the Lake Tumba Swampy Forests, Democratic Republic of Congo

Data on food items were collected from the Lac Tumba Swampy Forests (LTSF) with the objective to gauge the effect of food type and availability on the distribution of the bonobos. Bonobos at the LTSF feed on at least 61 plant species and eat more Terrestrial Herbaceous Vegetation (THV) than at other sites (t = 0.676, df = 3, p = 0.548 > 0.05; in- significant). Fruits were available for most of the year at sites within the LTSF. At the Mbou-Mon-Tour (MMT), a site with higher bonobo density, the mean density of 1.42 fruits/m 2 per month (range 0.62 - 3.82 fruits/m 2 per month) was re- corded, higher than in other sites where bonobos occur (general univariate linear model � = 0.422, t = 1.543, df = 11, p = 0.151, non-significant). In-site differences between MMT and other sub-sites in the LTSF were significant (t = 2.793, df = 12, p = 0.016 < 0.05). Fruit abundance in the LTSF ( X =138 fruits/km, SD = 13.80) was higher than in the Salonga Na- tional Park (SNP) ( X =83 fruits/km, SD = 6.49). There were five species of THV in the LTSF, with the most abundant being Megaphrynium macrostachyum (41.18%), which was scarce in the Lomako Forests. Comparisons between sites in- dicated that sites in SNP consistently had lower stem densities than sites in LTSF (t = -7.528, df = 3, p =0.005, signifi- cant). These results, in agreement with previous studies, concluded that the distribution of THV in different sites signifi- cantly determined the bonobo distribution.

A comparison of two mountain gorilla habitats in Bwindi Impenetrable National Park, Uganda

AbstractBwindi Impenetrable National Park, Uganda, is a small protected area (331 km2) within which there is large climatic and altitudinal variation. Therefore we compared habitat types and forest composition between two locations to investigate differences that may influence ecological conditions for large mammals, including endangered mountain gorillas. We demonstrate that there is considerable intersite variation in habitat types and spatial and temporal availability of vegetation resources of which the most apparent are the differences in species composition of plants and fruit availability. Buhoma (the lower altitude site) has a greater diversity of plant species and higher tree and shrub densities, yet has a much lower density of herbaceous vegetation eaten by gorillas compared with Ruhija. Fruit availability is significantly higher throughout the year in Buhoma compared with Ruhija. Both sites exhibit seasonal variation in fruit availability although they do not follow the same seasonal pattern, perhaps because of inherent asynchronous phenological differences amongst individual tree species. The results of this study are important because distribution and abundance of both terrestrial herbaceous vegetation and fruit resources are believed to influence aspects of feeding ecology for large mammals.

FOOD SEASONALITY AND SOCIOECOLOGY IN PAN : ARE WEST AFRICAN CHIMPANZEES ANOTHER BONOBO?

Comparative feeding ecology of African apes has recently been intensively in- vestigated principally for testing the THV (terrestrial herbaceous vegetation) hypothesis. The hypothesis argues that peaceful behavioral nature observed in bonobo (Pan paniscus) com- pared to chimpanzee (P. troglodytes) is derived from presence of suffi cient THV as fallback foods during lean periods, resulting from habitat segregation from more herbivorous gorillas. There was some supportive evidence for the hypothesis such as presence of feeding competi- tion for fi brous foods between chimpanzees and gorillas in sympatry. However, many cast doubt on the function of THV to maintain female cohesiveness. Overall, the ecological and social causality theorized in the THV hypothesis appears sound, but THV itself unlikely plays a major role, although critical data, bonobo ecology in particular, are still missing. Observed behavioral variation among chimpanzee subspecies suggests that West African chimpanzees are behaviorally more peaceful than East African subspecies. Intensive comparison of some socio-ecological parameters between Bossou and Kibale chimpanzees supported this idea. Data suggested that, also in this case, THV consumption is unlikely a key factor. Because West African chimpanzees, like bonobos, have probably been segregated from gorilla habi- tat for considerable amount of time in their evolutionary history, collective infl uence from coexisting with gorillas, not a competition over a single food source, must be responsible for socio-ecological differentiation observed among bonobo, Western chimpanzees, and Eastern chimpanzees.

Behavioral seasonality in Mahale chimpanzees.

To analyze how the chimpanzees in the Mahale Mountains National Park, Tanzania, change their grouping pattern, activity budget, travel speed, and travel distance within an annual cycle, I divided 1-year data into four periods. The Mahale chimpanzees have the behavioral flexibility to adapt to various climates and exhibited at least three behavioral seasons. In the early wet season, chimpanzees formed a few, large parties, and spent much time feeding on insects and animal meat. In the early and late dry seasons, chimpanzees maintained party sizes as large as in the early wet season, and traveled distances similar to the early wet season, but spent the most time feeding and traveling within the year. By contrast, in the late wet season chimpanzee parties broke up into more numerous, small groups, and traveled slowly over shorter distances. Although time spent feeding and traveling were the same as that in the early wet season, time spent feeding on terrestrial herbaceous vegetation (THV) was the highest in the year. The results suggest that chimpanzees travel longer, faster, and farther in seasons when they form large parties.