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Golden monkey ranging in relation to spatial and temporal variation in food availability
Abstract
Understanding the determinants of a species’ range use aids in understanding their ecological requirements, which in turn facilitates designing effective conservation strategies. The ranging behaviour of golden monkeys (Cercopithecus mitis kandti) in Mgahinga Gorilla National Park, Uganda was studied from January 2003 to February 2004 to establish habitat preferences. In each 0.25 ha grid cell in the group’s home range we quantified the basal area of food trees (n = 12,133 trees), measured bamboo (Arundinaria alpina) stems (n = 103,548), and estimated vine and shrub coverage. The evaluation of habitat preferences was facilitated by the fact that only five plant species, plus invertebrates (7.5%) constituted 96.4% of the group’s foraging effort; this included bamboo (59.9%), Maesa lanceolata (18.7%), Hypericum revolutum (6.8%), Galiniera saxifraga (2.1%) and Ilex mitis (1.4%). Phenology data were collected for all five food tree species, three vines, and two shrubs. Range use generally followed food tree basal area distribution and not the distribution of bamboo, with the abundance of M. lanceolata being more closely associated with home range use than any other food plant. Bamboo was ubiquitous in distribution and a vital year-round resource for golden monkeys, which they combined with other food items to meet their nutritional requirements. Illegal bamboo or tree extraction both pose a serious threat to the conservation of the golden monkey, but activities that affect food tree abundance will likely have the most influence on monkey persistence.
... Bamboo zones in the Albertine Rift region of East Africa provide habitat to species such as Archer's robin-chat Cossypha archeri and Rwenzori apalis Apalis ruwenzorii, two birds particularly associated with the open understory found in bamboo forests 14 . In addition, bamboo is a food resource for various African vertebrates, especially the Endangered mountain gorilla Gorilla beringei beringei and the Endangered golden guenon Cercopithecus mitis kandti [15][16][17] , also known as golden monkey. Bamboo can make up a considerable portion of the diet of these primates in the Virunga massif (central Albertine Rift region)-up to 15% and 60% of the annual feeding time of mountain gorillas and golden guenons is spend consuming bamboo, respectively 15,[17][18][19][20] -and other large herbivores such as buffalo, elephant and antelopes feed opportunistically on bamboo shoots when available 21 . ...
... In addition, bamboo is a food resource for various African vertebrates, especially the Endangered mountain gorilla Gorilla beringei beringei and the Endangered golden guenon Cercopithecus mitis kandti [15][16][17] , also known as golden monkey. Bamboo can make up a considerable portion of the diet of these primates in the Virunga massif (central Albertine Rift region)-up to 15% and 60% of the annual feeding time of mountain gorillas and golden guenons is spend consuming bamboo, respectively 15,[17][18][19][20] -and other large herbivores such as buffalo, elephant and antelopes feed opportunistically on bamboo shoots when available 21 . ...
... A lack of bamboo shoot availability might also not directly affect the nutrient uptake by individual golden guenons, as a large portion of their diet is made up of parts of mature bamboo (especially leaves) in addition to the occasional intake of other food items (fruits, flowers, leaves of other plants, insects) 17,41 . However, a lack of bamboo shoot regeneration is likely to impact golden guenon behaviour and population dynamics. ...
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.
... %: Butynski 1990) to leaves (44.1-46.9 %: Fairgrieve and Muhumuza 2003;Plumptre 2006;Twinomugisha and Chapman 2008) depending on location. Given their wide distribution and flexibility for a forest primate, blue monkeys as a species are considered to be at low risk of extinction (Kingdon et al. 2008). ...
... In contrast, bamboo was very scarce (<0.01 % of stems) within the range of Forest Group, though they did consume it occasionally (0.8 % of their overall diet). The high level of bamboo consumption by Fragment Group at Jibat is not unprecedented among blue monkeys because Cercopithecus mitis kandti in Mgahinga, Uganda obtains 60 % of its diet from bamboo (Twinomugisha and Chapman 2008). Further, another more distant relation, sometimes classified as a guenon (Grubb et al. 2003), the Bale monkey (Cercopithecus djamdjamensis), was found to eat 77 % bamboo at Odobullu, Ethiopia (Mekonnen et al. 2010). ...
Comparisons of the behavior and ecology of primates living in intact and fragmented forest are critical to the development of conservation strategies for the many primate taxa threatened by habitat loss. From July 2009 to April 2010, we investigated the habitat use, ranging behavior, and diet of two groups of Boutourlini’s blue monkeys (Cercopithecus mitis boutourlinii), a subspecies endemic to western Ethiopia, whose habitats had experienced different levels of disturbance at Jibat Forest. Forest Group occupied primarily continuous tree-dominated forest with little human disturbance whereas Fragment Group inhabited a heavily degraded 2- to 3-km2 forest fragment nearly surrounded by farmland and connected tenuously to the continuous forest by a narrow corridor of riverine forest. Mean daily path lengths for both groups were nearly identical (Forest Group: 799 m; Fragment Group: 783 m) and exhibited little seasonal variability. The mean home range areas of Forest Group and Fragment Group were 72.0 and 61.2 ha, respectively. Forest Group (N = 2232 feeding records) fed mostly on fruits (52.5 %), though they also ate animal prey (14.7 %), young leaves (11.1 %), shoots (8.7 %), and flowers (7.3 %). In contrast, fruits accounted for only 17.0 % of Fragment Group’s diet (N = 2903 feeding records), with shoots (29.8 %), young leaves (17.1 %), animal prey (13.1 %), seeds (9.6 %), and flowers (6.8 %) also making substantial contributions to their diet. Only Fragment Group engaged in crop raiding, consuming seeds from barley and wheat extensively (33–41 % of diet) during 2 mo. Fragment Group (N = 33) ate more plant species than Forest Group (N = 24), though both groups exploited a small number of plant species relative to other subspecies of blue monkeys. Our study revealed that, like most other blue monkey subspecies, Boutourlini’s blue monkeys are quite flexible in the habitats they occupy as well as in their foraging habits. Despite this ecological flexibility, the long-term conservation of Boutourlini’s blue monkey is far from assured given its limited distribution, the rapidly growing human population, and the high rates of forest clearance in western Ethiopia.
... For Mountain gorillas, bamboo sprouts are a preferred food and can contribute 90% of their diet in some periods (Weber, 1981;Elgart-Berry, 2004). Bamboo sprouts also provide a favoured food for African golden monkeys representing around 60% of their foraging (Aveling, 1984;Twinomugisha and Chapman, 2008). ...
... This trade-off assumption is the primary justification of those who argue for complete protection of the bamboo in the name of conservation (e.g. Twinomugisha and Chapman, 2008). ...
There are conflicting demands on bamboo (Yushania alpina (K. Schum.) Lin.) in Mgahinga Gorilla National Park (Virunga Volcanoes), Uganda. Local people lost legal access to bamboo when the park was gazetted in 1991 – but still request harvesting rights. Bamboo sprouts provide a key food for conservation significant Mountain gorillas (Gorilla beringei beringei) and African golden monkeys (Cercopithecus mitis kandti). We examined the impact of a localised harvest of mature bamboo on the production of new stems. We used a grid of 540 variable area plots to record and assess 9420 stems (including 1268 cut stems) and 1981 sprouts. Mean densities were 3.96 stems m−2 and 0.68 sprouts m−2. Densities and diameters were lower in areas with tree shade compared to those without. Densities of new stems were positively related to densities of older stems. Diameters of young stems were positively correlated with the diameters of older stems but younger stems were, in general, significantly larger. Cutting of mature stems had no detectable impact on either the density or diameter of subsequent new stems. Statistical power analysis adapted from pharmaceutical assessments indicates that a minor positive or negative impact remains possible (a positive effect appears more probable). We conclude that the bamboo is in a “building phase”, that densities and sizes of young stems are determined by the extent of the underground rhizome, and that this plot–scale relationship is not detectably influenced by harvesting older stems. Nonetheless, negative impacts may arise with repeated harvesting. Guidelines for any future harvest are suggested.
... One of the most obvious behavioral adaptations of animals to their environment lies in the modification of their home range size and use as consequence of the temporal variations of their habitat, e.g., baboons (Papio cynocephalus: Bronikowski and Altmann 1996), macaques (Macaca fuscata: Hanya et al. 2006), woolly monkeys (Lagothrix lagotricha poeppigii: Di Fiore 2003), gorillas (Gorilla gorilla beringei : Vedder 1984), golden monkeys (Cercopithecus mitis kandti: Twinomugisha and Chapman 2007), capuchins (Cebus olivaceus: Robinson 1986), and tamarins (Saguinus mystax and Saguinus fuscicollis: Culot et al. 2010). The characteristics of a home range are defined by the species' requirements in terms of survival and reproduction. ...
... Thus the daily path length and the size of a home range may be influenced by body size (Milton and May 1976), group size (Clutton-Brock and Harvey 1977;Dunbar 1988;Fashing et al. 2007;Izumiyama et al. 2003;Makwana 1978;Olupot et al. 1994), reproductive efforts, sex, age, interactions among conspecific groups (Isbell 1983), habitat structure (Izumiyama et al. 2003), and weather conditions (Clutton-Brock and Harvey 1977;Isbell 1983). Ranging behavior may also be influenced by feeding behavior, including diet (Boonratana 2000;Clutton-Brock and Harvey 1977;Harvey and Clutton-Brock 1981;Milton and May 1976), foraging strategies, and, finally, the availability of food resources (Di Fiore 2003;Hanya et al. 2006;Isbell 1983;Kaplin 2001;McLoughlin and Ferguson 2000;Olupot et al. 1997;Porter et al. 2007;Robbins and McNeilage 2003;Twinomugisha and Chapman 2007). ...
Food availability may influence primates’ home range size and use. Un-
derstanding this relationship may facilitate the design of conservation strategies. We
aimed to determine how fruit availability influences the ranging patterns of a group of
northern pig-tailed macaques (Macaca leonina) living around the visitor center of
Khao Yai National Park, Thailand. We predicted that macaques would increase their
range during low fruit abundance periods to gather high-quality food and that they
would go where there are more fruits or more fruits of particular species. We also
predicted that human food, linked to human presence, would attract the macaques.
We followed the macaques and recorded their diet and movements within their home
range. We superimposed a grid on kernels defining the monthly home range surface
to compare spatially macaques’ travel and the availability of fruits measured on
botanical transects. Our results showed that the macaques increased their monthly
home range in March, probably to obtain newly available fruits. During high fruit
abundance seasons, they spent more time near particular fruit species. In August and
September, although fruits became rare again, macaques kept their home range large,
perhaps to find enough fruits as supplies dwindled. Finally, from October to February,
they decreased their monthly home range size while consuming human food, a high-
quality item. In conclusion, the macaques used several ranging strategies according to
fruit availability. However, we think that, without human food, macaques would tend
to increase their range during low fruit abundance periods, as predicted.
... We assessed each marked tree for the relative abundance score of potential food resources (mature leaves, young leaves, flowers, and fruits) by visual inspection and using binoculars, with a relative abundance score ranging from 0 to 8 at intervals of 1. A score of 0 corresponds to a complete absence of that plant part, and a score of 8 corresponds to the plant part comprising > 87.5% of the crown (Twinomugisha and Chapman 2008;Mekonnen et al. 2018). We calculated the proportion of monitored trees bearing each of the phenophases every month for each study species. ...
Studying the diet and feeding behavior of primates is essential to understanding their ecology and designing effective conservation plans. Despite decades of study on the hamadryas baboon (Papio hamadryas) in lowland habitats, little is known about the feeding ecology of this species in highland ecosystems. To address this empirical gap, we tracked temporal changes in vegetation abundance and their relation to the dietary choices of hamadryas baboons in highland habitat at Borena-Sayint National Park (BSNP) in northern Ethiopia. We performed behavioral scan sampling on a focal study band of 21–37 hamadryas baboons over a 12-month period. We found that mature and young leaves were the most abundant plant parts throughout the year, while fruits and flowers were the least abundant, with significant seasonal variation that followed the bimodal pattern of rainfall characteristic of the Ethiopian highlands ecosystem. The annual diet of hamadryas baboons at BSNP consisted mostly of fruits (32.0%) and graminoid blades (21.2%), and included 52 food species across 22 families of plants and three families of animals. Food raided from nearby farms accounted for 8.8% of their diet. The availability of fruits and flowers was positively correlated with their consumption, suggesting that these are preferred foods, whereas graminoid blades, and other leaves, appeared to be less preferred foods. The feeding ecology of hamadryas baboons at BSNP differs considerably from that of lowland populations. The well-studied lowland hamadryas baboons in Awash National Park obtain much of their diet from Acacia species and palm fruit, whereas those at BSNP, where Acacia trees are rare and palms are absent, relied on Olinia rochetiana and Rosa abyssinica for a combined 27% of their annual diet. The reliance of hamadryas baboons at BSNP on cultivated crops for nearly one-tenth of their diet leads to conflict with humans and warrants more detailed study so that this issue can be addressed in conservation plans for the area.
... Furthermore, primate food resources can vary dramatically in space and between seasons (Brockman and Van Schaik, 2005;Jones, 2006;Tang et al., 2016;Twinomugisha and Chapman, 2008). Especially during the dry season plant foods become scarcer, patchier, and primate diets exhibit lower species richness and diversity (Hemming & Bynum, 2005;Sekulic, 1982). ...
... Animals relying on poor-quality diet have to spend more time foraging in degraded habitat which may affect their welfare in the long run. These include species feeding on bamboo, such as the golden monkey Cercopithecus mitis kandti [73], mountain gorilla Gorilla beringei beringei [74], and eucalyptus, such as the koala [75]. ...
Background
Habitat specialists living in human-dominated landscapes are likely to be affected by habitat fragmentation and human disturbances more than generalists. But there is a paucity of information on their response to such factors. We examined the effect of these factors on movement patterns of red pandas Ailurus fulgens , a habitat and diet specialist that inhabits the eastern Himalaya.
Methods
We equipped 10 red pandas (six females, four males) with GPS collars and monitored them from September 2019 to March 2020 in Ilam, eastern Nepal. We collected habitat and disturbance data over four seasons. We considered geophysical covariates, anthropogenic factors and habitat fragmentation metrics, and employed linear -mixed models and logistic regression to evaluate the effect of those variables on movement patterns.
Results
The median daily distance travelled by red pandas was 756 m. Males travelled nearly 1.5 times further than females (605 m). Males and sub-adults travelled more in the mating season while females showed no seasonal variation for their daily distance coverage. Red pandas were relatively more active during dawn and morning than the rest of the day, and they exhibited seasonal variation in distance coverage on the diel cycle. Both males and females appeared to be more active in the cub-rearing season, yet males were more active in the dawn in the birthing season. Two sub-adult females dispersed an average of 21 km starting their dispersal with the onset of the new moon following the winter solstice. The single subadult male did not disperse. Red pandas avoided roads, small-habitat patches and large unsuitable areas between habitat patches. Where connected habitat with high forest cover was scarce the animals moved more directly than when habitat was abundant.
Conclusions
Our study indicates that this habitat specialist is vulnerable to human disturbances and habitat fragmentation. Habitat restoration through improving functional connectivity may be necessary to secure the long-term conservation of specialist species in a human-dominated landscape. Regulation of human activities should go in parallel to minimize disturbances during biologically crucial life phases. We recommend habitat zonation to limit human activities and avoid disturbances, especially livestock herding and road construction in core areas.
... Identifying how animals divide their activities throughout the day and year-round offers clear perception into their interaction with the environment and their strategies for maximizing energetic and reproductive success [24]. Activity budgets of primates are commonly associated with strategies of energy conservation [25,26] and are affected by a predator or human pressure, social structure, season, or availability, distribution, and quality of food resources [27][28][29][30][31][32][33][34]. Primates may respond quite differently to forest disturbance, fragmentation, and related edge effects, which make the long-term survival of a particular primate species in an altered habitat depending on its specific habitat requirements [8,35]. ...
Geladas are the most distinctive of Ethiopian endemic mammals, representing the last extant species of primate genus that have a very restricted distribution in the northern Ethiopian plateau. The activity budget and feeding ecology of geladas (Theropithecus gelada obscurus) were studied around Abogedam Church, Ethiopia, from May to October 2014, encompassing dry and wet seasons. The scan sampling method was applied to collect behavioural data on the identified band. Activity scans were collected at 15-minute intervals for up to five minutes duration from 0700 to 1730 h. The activity recorded for each individual was the first activity that lasts for five seconds. During each scan, individuals were recorded as performing activities: feeding, moving, resting, playing, aggression, grooming, sexual activity, and others. On average, geladas devoted 57.19% feeding, 14.82% resting, 14.92% moving, 4.83% playing, 2.53% aggression, 4.14% grooming, 1.23% sexual activity, and 0.34% other activities such as vocalization, defecation, and urination. Forty-one plant species were consumed by geladas that belonged to 18 families of which 53.66% were grasses. This study provides basic information on further studies and motivates conservationists to plan the management of unprotected areas at the vicinity of agricultural lands where such endemic animals dwell.
... Identifying how animals divide their activities throughout the day and year-round offers clear perception into their interaction with the environment and their strategies for maximizing energetic and reproductive success [24]. Activity budgets of primates are commonly associated with strategies of energy conservation [25,26] and are affected by a predator or human pressure, social structure, season, or availability, distribution, and quality of food resources [27][28][29][30][31][32][33][34]. Primates may respond quite differently to forest disturbance, fragmentation, and related edge effects, which make the long-term survival of a particular primate species in an altered habitat depending on its specific habitat requirements [8,35]. ...
Geladas are the most distinctive of Ethiopian endemic mammals, representing the last extant species of primate genus that have a very restricted distribution in the northern Ethiopian plateau. e activity budget and feeding ecology of geladas (eropithecus gelada obscurus) were studied around Abogedam Church, Ethiopia, from May to October 2014, encompassing dry and wet seasons. e scan sampling method was applied to collect behavioural data on the identified band. Activity scans were collected at 15-minute intervals for up to five minutes duration from 0700 to 1730 h. e activity recorded for each individual was the first activity that lasts for five seconds. During each scan, individuals were recorded as performing activities: feeding, moving, resting, playing, aggression, grooming, sexual activity, and others. On average, geladas devoted 57.19% feeding, 14.82% resting, 14.92% moving, 4.83% playing, 2.53% aggression, 4.14% grooming, 1.23% sexual activity, and 0.34% other activities such as vocalization, defecation, and urination. Forty-one plant species were consumed by geladas that belonged to 18 families of which 53.66% were grasses. is study provides basic information on further studies and motivates conservationists to plan the management of unprotected areas at the vicinity of agricultural lands where such endemic animals dwell.
... However, we need to further explore the complex effect of fragmented habitats on bonobos and include more comprehensive landscape metrics and patch metrics in future studies. The seasonal patterns we observed in habitat use, dietary composition and spatial dispersion may be due to spatiotemporal variation in food availability, as shown in chimpanzees and many other primates species (e.g., Albert et al. 2013;Fiore 2003;Hanya et al. 2006;Porter et al. 2007;Robbins and McNeilage 2003;Twinomugisha and Chapman 2008). However, we need to explore the potential influence of spatiotemporal variation in food availability on diet, habitat use, ranging pattern, and activity budget, for example, by testing for preferred foods, fallback foods, and their distribution in specific habitat types. ...
Understanding the ecological and behavioral variation of primates is central to improving conservation strategies. Studies of chimpanzees (Pan troglodytes) have shown marked behavioral variability across a wide range of habitats. By comparison, bonobos (Pan paniscus) occur mainly in continuous forest sites, and socioecological models explaining behavioral differences between the two species are based on the assumption that bonobo habitat is richer and more stable than chimpanzee habitats. The objective of this study was to assess bonobo ecology in a forest-savanna mosaic. We specifically explored 1) bonobo home range size, habitat use, and dietary composition; 2) forest fragmentation in a bonobo community's home range; and 3) seasonality of dietary diversity, habitat use, and spatial distribution. Using 2 years of observational data on location, habitat type, and dietary composition, we found that the bonobo community's home range size, density, and dietary diversity were similar to those observed in continuous forest sites. Bonobos used areas with lower forest fragmentation than the surrounding areas and preferentially spent time in forested habitats. During the dry season, bonobos consumed a lower diversity of fruit species, spent more time in sparse forest with Marantaceae understory, and were closer to the seasonal center of their home range than during the rainy season. Our results contribute to our understanding of behavioral variation in bonobos and suggest that forest-savanna mosaic is valuable to bonobo conservation.
... Studies exploring ranging patterns in small ranging species, such as primates, typically use ground-based phenology to determine the influence of resource availability (Di Bitetti 2001;Kaplin 2001;Twinomugisha & Chapman 2007;Albert et al. 2013;Gabriel 2013;Campera et al. 2014;Santhosh et al. 2015). Ground-based phenology provides detailed and accurate information on the availability of specific food items, yet often lacks spatial coverage (Studer et al. 2007). ...
Understanding the determinants of ranging patterns in species susceptible to habitat fragmentation is fundamental for assessing their long‐term adaptability to an increasingly human‐dominated landscape. The aim of this study was to determine and compare the influence of ground‐based food availability, remotely sensed plant productivity, and indigenous forest use on the ranging patterns of the endangered samango monkey (Cercopithecus albogularis schwarzi). We collected monthly ranging data on two habituated samango monkey groups, from February 2012 to December 2016, from our field site in the Soutpansberg Mountains, South Africa. We used linear mixed models to explore how food availability, plant productivity and indigenous forest use influenced monthly ranging patterns, whilst controlling for group size, number of sample days and daylength. We found that as more areas of high plant productivity (derived from remotely sensed EVI) were incorporated into the ranging area, both total and core monthly ranging areas decreased. In addition, both total ranging area and mean monthly daily path length decreased as more indigenous forest was incorporated into the ranging area. However, we found no effect of either ground‐based food availability or remotely sensed plant productivity on ranging patterns. Our findings demonstrate the behavioral flexibility in samango monkey ranging, as samangos can utilize matrix habitat during periods of low productivity but are ultimately dependent on access to indigenous forest patches. In addition, we highlight the potential of using remotely sensed areas of high plant productivity to predict ranging patterns in a small ranging, forest‐dwelling guenon, over ground‐based estimates of food availability.
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... Adaptation to bamboo-dominated forests and diets appears to have evolved at least six times among the mammals: giant pandas in China [34,94], red pandas in India, Nepal, Bhutan, Myanmar, and China [69], bamboo lemurs (Hapalemur/Prolemur spp.) in Madagascar [26,95], Assamese macaques (Macaca assamensis) in China [68,96], golden monkeys in Uganda and Rwanda [67,97], and Bale monkeys in Ethiopia (this study; Table 5). Most of the primate taxa are members of ecologically-flexible genera (Macaca: [98]; Chlorocebus: [63]) or species (Cercopithecus mitis: [64,99]), while giant and red pandas belong to different more specialized families in the order Carnivora [69].w ...
Background:
Understanding the effects of habitat modification on the feeding strategies of threatened species is essential to designing effective conservation management plans. Bale monkeys (Chlorocebus djamdjamensis) are endemic to the rapidly shrinking montane forests of the southern Ethiopian Highlands. Most populations inhabit continuous bamboo forest subsisting largely on the young leaves and shoots of a single species of bamboo. Because of habitat disturbance in recent decades, however, there are now also several dozen small populations inhabiting isolated forest fragments where bamboo has been degraded. During 12-months, we assessed Bale monkey responses to habitat degradation by comparing habitat composition, phenological patterns, and feeding ecology in a largely undisturbed continuous forest (Continuous groups A and B) and in two fragments (Patchy and Hilltop groups).
Results:
We found that habitat quality and food availability were much lower in fragments than in continuous forest. In response to the relative scarcity of bamboo in fragments, Bale monkeys spent significantly less time feeding on the young leaves and shoots of bamboo and significantly more time feeding on non-bamboo young leaves, fruits, seeds, stems, petioles, and insects in fragments than in continuous forest. Groups in fragments also broadened their diets to incorporate many more plant species (Patchy: ≥ 47 and Hilltop: ≥ 35 species)-including several forbs, graminoids and cultivated crops-than groups in continuous forest (Continuous A: 12 and Continuous B: 8 species). Nevertheless, bamboo was still the top food species for Patchy group (30% of diet) as well as for both continuous forest groups (mean = 81%). However, in Hilltop group, for which bamboo was especially scarce, Bothriochloa radicans (Poaceae), a grass, was the top dietary species (15% of diet) and bamboo ranked 10th (2%).
Conclusions:
We demonstrate that Bale monkeys are more dietarily flexible than previously thought and able to cope with some degradation of their primary bamboo forest habitat. However, crop raiding and other terrestrial foraging habits more common among fragment groups may place them at greater risk of hunting by humans. Thus, longitudinal monitoring is necessary to evaluate the long-term viability of Bale monkey populations in fragmented habitats.
... There are a few mammal species that are specialized in eating bamboo (shoots), including giant pandas (Ailuropoda melanoleuca- Schaller et al. 1985) and bamboo rats (Dactylornys dactylinus -Emmons 1981); among primates, bamboo shoots feature importantly on the menu of eastern gorillas (Gorilla beringei -Casimir 1975;Fossey and Harcourt 1977;Yamagiwa et al. 2005), bamboo lemurs (Hapalemur spp. -Glander et al. 1989), snub-nosed monkeys (Rhinopithecus bieti- Grueter et al. 2009), golden monkeys (golden guenons, Cercopithecus mitis kandti- Twinomugisha and Chapman 2008), Bale monkeys (Chlorocebus djamdjamensis- Mekonnen et al. 2010), a population of Assamese macaques (Macaca assamensis- Huang et al. 2015), and to a lesser degree, golden langurs (Trachypithecus geei- Chetry et al. 2010) and owl-faced monkeys (Cercopithecus hamlyni- Kaplin et al. 2014). How primates alleviate the potentially toxic effects of cyanide ingestion is unknown. ...
Eastern gorillas (Gorilla beringei) are among the few mammal species that seasonally consume large quantities of young bamboo shoots, which are a rich source of energy. Here, we document how the consumption of bamboo shoots coincides with changes in behavior of adult mountain gorillas (Gorilla beringei beringei) monitored by the Dian Fossey Gorilla Fund’s Karisoke Research Center in Volcanoes National Park, Rwanda. We offer a preliminary analysis of possible mechanisms underlying this behavioral change by measuring energy intake rates and the presence of cyanide and alcohol—ingredients potentially associated with increased activity levels—in fresh bamboo shoots. The percentage of bamboo shoots in the diet of gorillas was correlated positively with the rate of play behavior shown by adults in 2 of the 3 study groups. Play behavior was not the result of better weather conditions and also did not reflect the availability of spare time. Rather, there is some, but not consistent, evidence for a link between energy intake rates and play behavior of adults. Cyanide was not detected in young bamboo shoots, and the presence of alcohol remains inconclusive, albeit unlikely. In sum, our results show that consumption of a high-quality food can have a direct influence on the activity budget (and by extrapolation energy expenditure) of mountain gorillas through increased rates of play behavior. However, the physiological aspects underlying this elevated activity warrant further investigation.
... During the dry season, the animals in most Neotropical forests are exposed to more stressful conditions than during the rainy season, such as food shortages and high temperatures (Murphy & Lugo, 1995;Hemingway & Bynum, 2005). To cope with these conditions, primates may modify their use of habitats (Twinomugisha & Chapman, 2007), and increase the time spent foraging or resting (Chaves et al. 2012b). ...
Habitat loss represents the main threats to primate populations in the Neotropical region, due mainly to modifications in habitat spatial configuration and the availability of food resources. Here, two areas of Atlantic Forest in northeastern Brazil, Fazenda Trapsa (FT), a 14-ha fragment, and Mata do Junco Wildlife Refuge (MJ), covering 522 ha, were studied. Floristic composition and phytosociological parameters were analyzed, and a Callicebus coimbrai group was monitored at each site (FT: July 2009-February 2013; MJ: July 2011-December, 2012). The vegetation at FT appeared to be at an early stage of regeneration, with a high diversity of trees and density of lianas, whereas MJ had taller trees, a larger basal area, and lower liana density indicating a more mature habitat. The longitudinal monitoring of the FT group indicated significant behavioral and ecological modifications related to the inter-annual variation in the distribution of resources. Between-group comparisons showed behavioral contrasts, in particular in foraging and the distribution of resting time, which indicated a time minimizing foraging strategy within FT group. However, the MJ group was active for longer during the day for longer time periods, even though it foraged less and rested more. Diets were predominantly frugivorous in both groups, with marked variation in the food items exploited. Despite inhabiting a smaller fragment, the FT group occupied a slightly larger home range (10.8 ha) than the MJ group (9.1 ha), but travelled much distances each day (964±120 m vs. 1073±300 m). Both groups tended to follow relatively circular routes each day, although the FT group revisited feeding patches more frequently in the dry season, and MJ in the rainy season. The life-history traits of each group varied according to the characteristics of each habitat, with major differences in the inter-birth interval and weaning periods. Overall, the data indicate that C. coimbrai is well adapted to habitat loss, at least over the short- to medium term, but that more data will be necessary in order to plan habitat management strategies for the long-term conservation of the species.
... Intriguingly, there appears to be at least 1 additional guenon, the golden monkey (Cercopithecus mitis kandti), that shares Bale monkeys' specialization on bamboo as a food source though to a somewhat lesser degree. In particular, bamboo (Arundinaria alpina), primarily young leaves, accounted for 52.4–59.9% of the overall diet of golden monkeys at Mgahinga, Uganda (Twinomugisha et al. 2006; Twinomugisha and Chapman 2008). Like Bale monkeys at Odobullu, golden monkeys at Mgahinga also consumed an unusually species-poor diet (16 species) (Twinomugisha et al. 2006). ...
Bale monkeys (Chlorocebus djamdjamensis) are little-known primates endemic to the forests of the Bale Massif and Hagere Selam regions of Ethiopia. From August 2007
to May 2008, we conducted the first ever study of the species’ behavior and ecology, focusing in particular on its diet, activity
patterns, and ranging ecology in the Odobullu Forest. We studied 2 neighboring groups (group A: 55–60 members; group B: 46–50
members) and conducted behavioral scan samples on the first 2–5 individuals sighted at 15-min intervals. Feeding accounted
for 65.7% of the activity budget, followed by moving (14.4%), resting (10.7%), social (7.1%), and other behaviors (2.4%).
Overall diet during the study was dominated by young leaves (80.2%), though subjects also ate fruits (9.6%), flowers (3.1%),
animal prey (2.3%), shoots (1.5%), stems (1.4%), mature leaves (1.1%), and roots (0.9%). Bale monkeys consumed only 11 plant
species; of these, the top 5 species accounted for 94.3% of their diet. The top food item, bamboo (Arundinaria alpina), was responsible for a remarkable 76.7% of their diet, with most (95.2%) of the bamboo consumption consisting of young leaves.
Mean daily path length for the study groups was 928m and mean (100% minimum convex polygon) home range size was 15.2ha.
Though we are cautious in drawing conclusions from only 2 groups, the larger group traveled further per day and occupied a
larger home range, patterns suggesting scramble competition may be occurring in Bale monkey groups at Odobullu. The dietary
specialization of Bale monkeys on bamboo makes them unique among Chlorocebus spp. and suggests an intriguing ecological convergence with the golden monkeys (Cercopithecus mitis kandti) of Uganda and bamboo lemurs (Hapalemur spp.) of Madagascar. Their narrow ecological niche, limited geographic distribution, and bamboo harvesting by local people
for commercial purposes place Bale monkeys at risk of extinction. To ensure the long-term survival of Bale monkeys, appropriate
management action should be taken to conserve the species and the bamboo forests upon which it depends.
Keywordsactivity budget-bamboo-feeding ecology-home range-quantitative natural history-scramble competition
Human-wildlife conflict, in particular crop-foraging, challenges conservationists worldwide. Endangered golden monkeys (Cercopithecus mitis kandti) are frequent crop-foragers around Volcanoes National Park (VNP), Rwanda. To evaluate the impact of crop-foraging behaviour on monkeys and farmers, we interviewed 45 farmers near VNP using a structured questionnaire and organised a workshop for local and regional actors to discuss mitigation measures. To investigate differences in monkey behaviour when foraging inside versus outside VNP, and to inform mitigation strategies, we collected ad libitum behavioural data from one habituated golden monkey group for 11 weeks. We tested the feasibility of a taste aversion technique to deter monkeys, by placing chilli-laced potatoes in harvested potato fields adjacent to the study group’s home range but found that experimental aversion techniques were logistically challenging. Of 38 farmers, 95% experienced potato loss to monkeys and 36% of 44 farmers threw objects at/chased monkeys in the previous farming season. Farmers and workshop participants judged the most effective way to mitigate crop-foraging to be through improvement of existing crop-guarding. Behavioural observations indicated increased vigilance behaviour and decreased social behaviour when in farmland. Monkeys (N = 9) that visited the experimental area avoided chilli-laced potatoes but continued to forage on nearby crops. In conclusion, our results indicate that crop-foraging can negatively impact farmers' livelihoods and attitudes and can increase vigilance behaviour of monkeys. Our multi-faceted approach enabled the involvement of a wide range of stakeholders, highlighted the urgent need to improve existing management measures and explored alternatives to facilitate positive coexistence between monkeys and farmers.
Background
Connectivity is an important landscape attribute in ecological studies and conservation practices and is often expressed in terms of effective distance. If the cost of movement of an organism over a landscape is effectively represented by a raster surface, effective distances can be equated with the cost-weighted distance of least-cost paths. It is generally recognized that this measure is sensitive to the grid’s cell size, but little is known if it is always sensitive in the same way and to the same degree and if not, what makes it more (or less) sensitive. We conducted computational experiments with both synthetic and real landscape data, in which we generated and analyzed large samples of effective distances measured on cost surfaces of varying cell sizes derived from those data. The particular focus was on the statistical behavior of the ratio—referred to as ‘accuracy indicator’—of the effective distance measured on a lower-resolution cost surface to that measured on a higher-resolution cost surface.
Results
In the experiment with synthetic cost surfaces, the sample values of the accuracy indicator were generally clustered around 1, but slightly greater with the absence of linear sequences (or barriers) of high-cost or inadmissible cells and smaller with the presence of such sequences. The latter tendency was more dominant, and both tendencies became more pronounced as the difference between the spatial resolutions of the associated cost surfaces increased. When two real satellite images (of different resolutions with fairly large discrepancies) were used as the basis of cost estimation, the variation of the accuracy indicator was found to be substantially large in the vicinity (1500 m) of the source but decreases quickly with an increase in distance from it.
Conclusions
Effective distances measured on lower-resolution cost surfaces are generally highly correlated with—and useful predictors of—effective distances measured on higher-resolution cost surfaces. This relationship tends to be weakened when linear barriers to dispersal (e.g., roads and rivers) exist, but strengthened when moving away from sources of dispersal and/or when linear barriers (if any) are detected by other presumably more accessible and affordable sources such as vector line data. Thus, if benefits of high-resolution data are not likely to substantially outweigh their costs, the use of lower resolution data is worth considering as a cost-effective alternative in the application of least-cost path modeling to landscape connectivity analysis.
The field of primatology has reached the stage where there are sufficient long-term studies and many shorter investigations on the same species at many different locations, in which we are able to appreciate how variable the behaviour of primates can be and how predictable their environment is over space and time. For example, redtail monkeys (Cercopithecus ascanius) exhibit extreme flexibility in diet; i.e. within the same national park, the amount of time they spend eating fruit varies from 36 to 60% of their foraging time, and among populations, time spent eating fruit ranges from 13 to 61%. Similarly, long-term phenological data from the same area encompassing over two decades illustrate that fruit availability can vary among years by as much as eightfold. While data have steadily accumulated on how variable primate behaviour and proposed environmental predictors of behaviour can be, this information has not been used to effectively re-evaluate theory. For example, current primate socioecological theory has derived general frameworks using the average behavioural traits of species or genera, but these new data suggest it is inappropriate to use such averages. Similarly, environments have often been characterized by single studies of 2 years or less, which does not sufficiently account for environmental variation. Here, we present examples of behavioural and ecological variation and consider ways that our field could advance in the future by considering this variation.
Human modification of ecosystems is threatening biodiversity on a global scale. For example, it is estimated that, during the 1990s, 16 million ha of forest were lost globally each and every year, of which 15.2 million ha were tropical forest.
The polytypic Cercopithecus mitis Wolf, 1822, species is widely distributed in Africa, from southern Somalia in the north to the eastern Cape province of the Republic of South Africa in the south. The samango monkeys at Cape Vidal (Cercopithecus mitis erythrarchus) are found close to (within 500 km of) the southern limit of the range of the species group. We examine the proposition that, due to greater seasonality of climate and food availability at southern latitudes, samango activity patterns define the extent of the behavioural response capabilities of the C. mitis species group, both for the troop as a whole and for individual age-sex classes. Activity patterns are described. Although samangos appear to have activity patterns grossly similar to those of other C. mitis populations, the seasonal and diurnal timing of these activities is influenced by food abundance, temperature and day length. Activity patterns are compared across the C. mitis group, leading to the conclusion that samango activity is not indicative of the behavioural limits of the species group. Age-sex class differences in activity are briefly examined and discussed; age-sex class differences in activity seem to underlie differences in foraging strategy between the classes.
Assumptions behind optimal foraging theory are: 1) an individual's contribution to the next generation (its fitness) depends on behaviour during foraging; 2) there should be a heritable component of foraging behaviour (the actual innate foraging responses or the rules by which such responses are learned), and the proportion of individuals in a population foraging in ways that enhance fitness will tend to increase over time; 3) the relationship between foraging behaviour and fitness is known; 4) evolution of foraging behaviour is not prevented by genetic contraints; 5) such evolution is subject to 'functional' constraints (eg related to the animal's morphology); and 6) foraging behaviour evolves more rapidly than the rate at which relevant environmental conditions change. The review considers recent theoretical and empirical developments, dealing with behaviour of animals while they are foraging (but ignoring the timing of and the amount of time allocated to such behaviour). Ideas considered include risk aversion and risk proneness; optimal diet; optimal patch choice; optimal patch departure rules; optimal movements; and optimal central place foraging. Means of evaluating optimal foraging theory are discussed. -P.J.Jarvis
Central place foraging models assume that animals return to a single central place such as a nest, burrow, or sleeping site. Many animals, however choose between one of a limited number of central places. Such animals can be considered Multiple Central Place Foragers (MCPF), and such a strategy could reduce overall travel costs, if the forager selected a sleeping site close to current feeding areas. We examined the selection of sleeping sites (central places) by a community of spider monkeys (Ateles geoffroyi) in Santa Rosa National Park, Costa Rica in relation to the location of their feeding areas. Spider monkeys repeatedly used 11 sleeping trees, and they tended to choose the sleeping site closest to their current feeding area. A comparison of the observed travel distances with distances predicted for a MCPF strategy, a single central place strategy, and a strategy of randomly selecting sleeping sites demonstrated (1) that the MCPF strategy entailed the lowest travel costs, and (2) that the observed travel distance was best predicted by the MCPF strategy. Deviations between the observed distance travelled and the values predicted by the MCPF model increased after a feeding site had been used for several days. This appears to result from animals sampling their home range to locate new feeding sites.
For nearly three decades, the academic community has clearly recognized that many primate populations are severely threatened by human activities.1-3 In 1983, Wolfheim4 estimated that more than 50% of all primate species faced some form of threat. Over a decade later, the Primate Specialist Group of the Species Survival Commission of the World Conservation Union5 estimated that half of the world's 250 species of primates were of serious conservation concern. In a recent review of the current status of primate communities, Wright and Jernvall6 commented that it was an achievement for primate conservationists that we had not lost any species in the last millennium. It is ironic that the first documented extinction of a widely recognized primate taxon occurred just as we entered the new millennium.7 Based on surveys in Ghana and Cote d'lvoire, Oates and colleagues7 have failed to find any surviving populations of Miss Waldron's red colobus (Procolobus badius waldroni), a primate taxon endemic to this region and one that some authorities consider worthy of species status. Because 96 primate species are now considered to be critically endangered or endangered,6,8,9 much must be done in the near future to ensure that extinction curves do not lag behind tropical deforestation and high levels of commercial and subsistence hunting.10.
Optimization models help us to test our insight into the biological constraints that influence the outcome of evolution. They serve to improve our understanding about adaptations, rather than to demonstrate that natural selection produces optimal solutions.
The author summarizes 20 years of research in the Kibale forest in Uganda. The main body of the book demonstrates the adverse effects of logging on community structure and other aspects of forest ecology. The author provides evidence that future logging must be done at far lower intensities than is currently the norm, if intact ecosystems are to be maintained. Detailed recommendations for harvest plans compatible with the conservation of biodiversity and ecological integrity are outlined. Struhsaker addresses the underlying causes of tropical deforestation and concludes that although there are numerous proximate factors, the ultimate causes are rapidly increasing human populations and rates of consumption per capita. Comparisons with relevant studies elsewhere in the tropics are drawn and specific recommendations to address the problems are offered.
The colobus monkeys and gorillas of African forests share a strong tendency to depend on foliage during lean seasons. In many areas, both kinds of primate are threatened by habitat destruction. But while the total removal of natural habitat is clearly a major threat to the survival of many African forest primates, an analysis of survey data suggests that human predation tends to have a greater negative impact on primate populations than does selective logging or low-intensity bush-fallow agriculture. In the absence of hunting, the population density of colobus monkeys correlates with the protein: fibre ratio of mature tree foliage in their habitat, and the density of gorillas appears to be correlated with the abundance of terrestrial herbaceous vegetation. Because moderately disturbed forest can be relatively rich in high-quality lean-season folivore foods, such forest sometimes supports a higher density of folivorous primates than forest that has not been recently disturbed but that has been subject to hunting. Conservation plans for African forests should place more emphasis on the control of hunting and less on rural development, and long-range plans should also allow for the strong possibility of political instability.
A recensus of the Amboseli vervets in 1975 revealed a significant decline of about 43 percent in their numbers since 1964. The young juvenile age class showed the greatest decrease; the juvenile age class had declined less. Numbers of adults and subadults seemed unaffected, although there was a suggestion of an incipient decline in the males of these two age classes. This decrease in vervets is attributed to a natural reduction in their food resources. Natality remained high, and the birth season had not changed.
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/km^2, including 682-889 kg/km^2 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.
This study quantifies the effects of low-intensity logging (affecting <10% of the forest surface) on leaf chemistry, leaf and fruit production, and their effects on lemurs in a dry deciduous forest in western Madagascar. Logging exposed the remaining trees to more sunlight. Within a single tree and among trees, this resulted in higher protein concentrations in sun-exposed leaves, while fiber content remained constant. Concentrations of condensed tannins were also higher at higher sun exposure, but they leveled off at lower light intensities before protein and sugar concentrations. Within the 2-yr study period, crown extension due to higher availability of sunlight could compensate only for parts of the crown area lost due to logging. Thus, the biomass of leaves available was reduced, while average leaf quality (measured as the ratio of protein to fiber) increased. Fruit production was also positively correlated with sun exposure of the tree crown. Since fruits of the main timber trees (Commiphora spp.) are rarely consumed by frugivorous lemurs, removal of these trees increases sun exposure of other potential food trees for frugivores. At the described level of logging intensity, sightings of all lemur species increased (significantly in three out of seven species at P less than or equal to 0.05) compared to the pre-logging state and two control plots. This increase was attributed to increased fruit production and higher protein concentration in sun-exposed leaves. In natural forests, treefall gaps may have effects similar to those of logging in the present study. Low level disturbances, in general, may be important for the carrying capacity for folivorous and frugivorous lemurs and possibly for most primates.
An estimate of the above-ground biomass of leaf and wood in the shrubs and trees of Eucalyptus populnea woodland near Cobar, N.S.W., was made, by regression of leaf and wood weight on height or trunk diameter of the most common species. A new double regression technique was used for E. populnea to avoid destructively sampling whole trees. The mass of branches was regressed on primary branch diameter and these equations were used to estimate the total mass of crowns of trees. The estimated crown mass was then regressed on trunk diameters. Regression equations for estimation of mass of wood and leaf are provided for Geijera parvifora, Cassia nemophila, Dodonaea viscosa, Eremophila mitchellii, E. sturtii, E. bowmanii, Myoporum deserti and young Acacia aneura. The error of the estimates varied between 3 and 18% for different species. Log transformation of the data usually improved the correlation coefficients obtained but sometimes increased the standard error of the estimate. Estimates based on canopy measurements were rarely more accurate than those from height or trunk diameter. The overall estimate of biomass was 3.4 t of leaf and 51.4 t of wood per ha with a standard error of < 15%.
Transect surveys were carried out in seven western Amazonian upland forest sites and compared with four additional sites to examine effects of hunting by humans on the structure of species-rich primate communities. Primate body mass was a strong positive correlate of its crude and metabolic population biomass in non-hunted but not in hunted sites. Primate body mass was a good negative correlate of population density in hunted but not in non-hunted sites. Group density was not clearly affected by hunting activity. Large primates had significantly lower group densities than small primates in both hunted and non-hunted sites. These trends are largely a consequence of differences in abundance of large-bodied genera (i.e.Alouatta, Ateles and Lagothrix), accounting for the bulk of the primate biomass in non-hunted sites, but being over-harvested or becoming extinct in sites hunted by man.
Many types of biological studies require the estimation of food abundance in tropical forests, and a variety of methods have been used to estimate this parameter. Here we compare the accuracy and precision of three methods for estimating the fruit abundance (biomass and number) of tropical tree species: tree diameter, crown volume, and visual estimation. Diameter at breast height (DBH) was the most consistently accurate method and exhibited low levels of interobserver variability. Generally, crown volume was neither precise nor accurate. The visual estimation method was accurate for trees with very large fruit, but exhibited high interobserver variability.
If logging is to be compatible with primate conservation, primate populations must be expected to recover from the disturbance and eventually return to their former densities. Surveys conducted over 28 years were used to quantify the long-term effects of both low- and high-intensity selective logging on the density of the five common primates in Kibale National Park, Uganda. The most dramatic exception to the expectation that primate populations will recover following logging was that group densities of Cercopithecus mitis and C. ascanius in the heavily logged area continued to decline decades after logging. Procolobus tephrosceles populations were recovering in the heavily logged areas, but the rate of increase appeared to be slow (0.005 groups/km(2) per year). Colobus guereza appeared to do well in some disturbed habitats and were found at higher group densities in the logged areas than in the unlogged area. There was no evidence of an increase in Lophocebus albigena group density in the heavily logged area since the time of the logging, and there was a tendency for its population to be lower in heavily logged areas that in lightly logged areas. In contrast to the findings from the heavily logged area, none of the species were found at a lower group density in the lightly logged area than in the unlogged area, and group densities in this area were not changing at a statistically significant rate. The results of our study suggest that, in this region, low-intensity selective logging could be one component of conservation plans for primates; high-intensity logging, however, which is typical of most logging operations throughout Africa, is incompatible with primate conservation.
1. The Budongo Forest Reserve has been logged selectively for over 60 years. Most compartments in the Reserve have records of the volume of timber removed, the date of harvesting, and of treatments carried out to encourage regeneration of valuable timber species. 2. Line transect surveys of the five diurnal primates resident in this forest were carried out in eight of these compartments; two of which had never been logged and six of which had been harvested at approximately 10-year intervals since 1940. 3. Densities were calculated using the computer package DISTANCE. It was found that the 'Hazard Rate Model' fitted the observer-primate distance data better than other models. Densities over the whole forest were as follows: Cercopithecus mitis sthuhlmannii 43.9 km(-2); C. ascanius schmidti 33.3 km(-2); Colobus guereza occidentalis 39.3 km(-2); Papio anubis 11.7 km(-2); Pan troglodytes schweinfurthii 1.3 km(-2). 4. Only C. guereza showed any significant correlation between logging date and animal density, and none of the primates showed any correlation with the volume of timber removed. For three of the primates (C. guereza, C. mitis and C. ascanius) there were significantly higher numbers in the logged compartments when compared with those that were not logged. 5. Cercopithecus mitis and C. ascanius showed significant correlations between the percentage of different forest types and the densities of the primates in each compartment. In particular there was a positive correlation with the 'mixed' forest type that foresters have been encouraging through their management practices. It is concluded that these two primates and C. guereza have benefited from logging in Budongo and that logging has had little effect on the other two primates.
Abstract The colobus monkeys and gorillas of African forests share a strong tendency to depend on foliage during lean seasons. In many areas, both kinds of primate are threatened by habitat destruction. But while the total removal of natural habitat is clearly a major threat to the survival of many African forest primates, an analysis of survey data suggests that human predation tends to have a greater negative impact on primate populations than does selective logging or low-intensity bush-fallow agriculture. In the absence of hunting, the population density of colobus monkeys correlates with the protein: fibre ratio of mature tree foliage in their habitat, and the density of gorillas appears to be correlated with the abundance of terrestrial herbaceous vegetation. Because moderately disturbed forest can be relatively rich in high-quality lean-season folivore foods, such forest sometimes supports a higher density of folivorous primates than forest that has not been recently disturbed but that has been subject to hunting. Conservation plans for African forests should place more emphasis on the control of hunting and less on rural development, and long-range plans should also allow for the strong possibility of political instability.
This study examines the regeneration of indigenous tree species in the formerly encroached area in Mgahinga Gorilla National Park (MGNP), south‐western Uganda. Before gazetting in 1992, MGNP had basically been agricultural land for well over 50 years. The distribution of exotic vegetation was established using a Geographical Positioning System receiver and indigenous vegetation was sampled by establishment of quadrats along transect lines.
Observations indicated that approximately 2% of the old cropland was covered by exotic woodlots. Black wattle ( Acacia mearnsii ) and Eucalyptus trees were found to be the most widely distributed and Pinus patula the least distributed species in the park. Species numbers of indigenous trees ( n = 26) were high in the old cropland, compared with twelve species observed in exotic woodlots. The natural forest supported the highest (75%) stem density and the lowest (4%) stem density was recorded in exotic woodlots. Seedling class (< 2 cm, d.b.h.) accounted for the majority of juveniles, with the lowest stem density (1350 seedlings ha ⁻¹ ) recorded in exotic woodlots compared with 6609 seedlings ha ⁻¹ in the old cropland and 24,625 seedlings ha ⁻¹ in the natural forest. The levels of tree diversity and stocking characteristics recorded under the exotic species suggest that a low diverse community of native species may exploit this environment.
Abstract Many different techniques have been used to estimate biomass for ecological, agricultural and forestry research. The most suitable technique depends on available budget, accuracy required, structure and composition of the vegetation, and whether species and component biomass are required. A survey of the methods that have been used to estimate biomass is given, and the advantages and disadvantages of direct sampling, calibrated visual estimation and double sampling techniques are discussed. The relative cost and accuracy of each technique are summarized and recommendations are made for the use of the techniques in different vegetation complexes, such as discrete shrubs or trees, patchy vegetation, homogeneous vegetation, and species-rich inhomogeneous heathland.
We investigated the relation between temporally varying resources, diet composition, and seed-handling behaviors in a group of blue monkeys (Cercopithecus mitis doggetti) in a tropical montane forest of Rwanda. Changes in diet composition were related to concurrent phenological studies of fruit-producing trees, and density and abundance of tree resources within the monkey's home range. Fruit composed nearly 50 percent of the diet. Over 50 percent of the fruits eaten had juicy fleshy pulp. Observations of seed handling behavior provided insights into the role of these animals as potential seed dispersal agents. The monkeys moved the seeds of 29 species out of parent canopies by defecating seeds intact and by potentially carrying seeds in cheek pouches and dropping them later. Seeds of 18 species were found intact in fecal piles. Our study showed community-level phenology patterns did not indicate a decrease in fruit availability during the study period, but an analysis of the preferred fruits consumed by the monkeys showed distinct periods of low fruit availability The study period included two dry seasons; only one of these produced a period of fruit scarcity for the animals. The animals employed different strategies during times of preferred fruit scarcity They increased consumption of leaves and other fleshy fruits, and diet diversity increased, or became mainly seed predators and diet diversity decreased. The variable responses of these monkeys to changes in food availability highlights their dietary plasticity and imposes significant variations in their role as potential seed dispersers.
The sudden appearance of diseases like SARS (severe acute respiratory syndrome1), the devastating impacts of diseases like Ebola on both human and wildlife communities,2, 3 and the immense social and economic costs created by viruses like HIV4 underscore our need to understand the ecology of infectious diseases. Given that monkeys and apes often share parasites with humans, understanding the ecology of infectious diseases in nonhuman primates is of paramount importance. This is well illustrated by the HIV viruses, the causative agents of human AIDS, which evolved recently from related viruses of chimpanzees (Pan troglodytes) and sooty mangabeys (Cercocebus atys5), as well as by the outbreaks of Ebola virus, which trace their origins to zoonotic transmissions from local apes.6 A consideration of how environmental change may promote contact between humans and nonhuman primates and thus increase the possibility of sharing infectious diseases detrimental to humans or nonhuman primates is now paramount in conservation and human health planning.
Food resources are arguably the most common limiting factor for most species, yet little is known about how food quantity and quality interact to determine the size and distribution of wildlife populations. Frugivores may be limited by food quality since fruits, unlike leaves, are typically low in protein and minerals. Understanding the factors influencing frugivore population dynamics is particularly important due to rapid habitat loss and the need to construct informed management plans. Therefore, this study used redtail monkeys in Kibale National Park, Uganda as a model frugivore to (1) compare nutrient intake, reproduction, and habitat use patterns for three redtail groups in an unlogged and heavily logged area; and (2) examine relationships between nutrient intake and redtail population densities across five habitats. Feeding time and intake of crude protein, lipids, and minerals were higher in diets consumed by groups in unlogged areas than heavily logged areas. Intake of both copper and sodium intake was below NRC requirement levels suggested for macaques. Food availability in the unlogged areas was 3.5 times higher than the heavily logged area. Across five study sites, absorbable copper and the ratio of copper to caloric intake in redtail diets were significantly related to redtail population density. These results suggest that food quality is an important factor determining frugivore population density in anthropogenically disturbed frugivore habitats. Copper deficiency, which has been associated with population declines of wild herbivores, has the potential to be a key factor limiting densities of frugivores in tropical habitats.
The behavior of spider monkeys (Ateles geoffroyi) at sleeping sites and the characteristics of these sites were studied in Santa Rosa National Park, Costa Rica. The spider monkeys tended to congregate just prior to dusk at a number of sleeping sites which were repeatedly used (81.6%), but occasionally they slept in trees which were only used once (18.4%). All of the regularly used sleeping trees were not used concurrently, but rather, there was a rotation between sites. In general, males were not encountered at regularly used sleeping sites as often as other age/sex classes, and when they were in all male subgroups, they did not sleep in repeatedly used sites. The trees used as regular sleeping sites tended to be large, but such trees were common in the group's home range. The size of the subgroups attending repeatedly used sleeping trees was large when food was abundant and small when food was scarce. It is suggested that this relationship reflects that the costs of travelling to the sleeping site would be more easily recovered when food was abundant than when food was scarce.
Given the degree to which tropical ecosystems are currently being disturbed by human activities, it is essential to set priorities for conservation and thus it becomes important to consider how best to set these priorities. From this perspective, this study provides the first detailed investigations of Cercopithecus mitis kandt i, the golden monkey, focusing on the population in Mgahinga Gorilla National Park (MGNP), Uganda. Specifically, we (1) establish the current status of the golden monkey in terms of population size and distribution within the park in relation to vegetation types and altitude, and (2) investigate the golden monkey's feeding ecology. A total of 67 censuses of 4+ km transects were conducted along a cumulative distance of 299 km and 132 social groups were encountered. Densities were estimated to have increased by 1.6 times since a census 8 years ago, and the total population in the park is estimated to be between 3164 and 5059 individuals. The average size of golden monkey groups in MGNP is 30 individuals (range 3-62). This is similar to that of other subspecies in neighbouring forests. In contrast, the census conducted 8 years before estimated average group size to be eight individuals. Golden monkeys were observed to eat 21 plant species and they were inferred to eat an additional eleven from signs left behind and reports. Both study groups relied upon leaves (primarily young leaves), fruits and invertebrates for food, but the amount of time they fed on these different types of foods varied between the groups. Given the apparent increase in density since the census 8 years ago, the golden monkeys of MGNP appear to be doing well. However, given the number of snares and the extent of illegal extraction of bamboo found during the census, conservation efforts should be increased.
Studies of foraging behaviour have proliferated over the past 30 years. Two schools of thought have emerged, one focusing on theoretical aspects (so-called 'optimal foraging theory'), the other on empirical studies. We summarize both, showing how they have evolved and begun to coalesce during the past decade. The emerging new framework is more complex than previous models, combining theory with observation. Modern phylogenetic methods promise new insights into how animal foraging has evolved.
Two opposing hypotheses concerning determinants of mangabey (Cercocebus albigena) ranging patterns have been advocated. One hypothesis suggests that ranging patterns of mangabeys are largely a response to fruit availability, while the other hypothesis advocates that concerns of fruit availability are supplemented or overridden by concerns of fecal contamination and that the risk of parasite infection, especially during dry weather, determines their pattern of range use. In this 9 month study of mangabeys in the Kanyawara study area of Kibale National Park, mangabeys moved longer distances during the wet season than during the dry season. There were no seasonal differences in group spread, number of 50 by 50 m quadrats used, or in quadrat overlap between sequential sample periods. Intensity of quadrat use was closely related to the number of fruiting trees/lianas in the quadrats, irrespective of season. These findings are consistent with the hypothesis that fruit availability is a main factor influencing mangabey ranging patterns. The results are not consistent with the hypothesis that mangabey ranging patterns largely reflect differential seasonal risk of parasite infection.
Conservation efforts to protect chimpanzees in their natural habitat are of the highest priority. Unfortunately, chimpanzee density is notoriously difficult to determine, making it difficult to assess potential chimpanzee conservation areas. The objective of this study was to determine whether chimpanzee density could be predicted from the density of trees that produce large, fleshy fruits. Using chimpanzee nest counts from six sites within Kibale National Park, Uganda, collected during a year-long study, a predictive trend was found between chimpanzee nest density and large, fleshy-fruit tree density. This relationship may offer a quick, reasonably reliable method of estimating potential chimpanzee densities in previously unsurveyed habitats and may be used to evaluate the suitability of possible re-introduction sites. Thus, in conjunction with other survey techniques, such as forest reconnaissance, it may provide an effective and efficient means of determining appropriate chimpanzee habitat in which to allocate conservation efforts.
Understanding the determinants of animal abundance has become more vital as ecologists are increasingly asked to apply their knowledge to the construction of informed management plans. However, there are few general models are available to explain variation in abundance. Some notable exceptions are studies of folivorous primates, in which the protein-to-fiber ratio of foods has been shown to predict biomass. Here we examine the generality of Milton's [American Naturalist 114:363-378, 1979] protein/fiber model by providing a detailed analysis of diet selection in black-and-white colobus monkeys (Colobus guereza), and applying the model to populations shown to be stable; an assumption not previously examined. Based on observations of two groups of black-and-white colobus in Kibale National Park, Uganda, and one group in a forest fragment, we documented that the animals selected young leaves that had more protein, were more digestible, and had a higher protein-to-fiber ratio than mature leaves. The mature leaves did not differ from young leaves with respect to secondary compounds or mineral content (with the exceptions of copper and zinc). All of the colobus groups selected foods with a high protein-to-fiber ratios. However, one group also selected more digestible foods, and in another group, foraging efforts were positively related to zinc and negatively related to potassium. Previous studies that examined Milton's protein/fiber model did not demonstrate that the study populations were stable. If some populations were not at carrying capacity, then the correlations drawn between food availability and/or quality and folivore biomass may have been spurious. To address this issue, we censused a series of forest fragments in 1995 and again in 2000. We found that the populations in these fragments had declined from 165 in 1995 to 119 animals in 2000. However, based on evidence of population stability and lack of forest disturbance, we concluded that five of the original populations were stable. The biomass of these populations was related to the protein-to-fiber ratio of the fragment's trees. Combining our data with published data, we demonstrate that the protein-to-fiber ratios of mature leaves available to these folivorous primates accounted for 87% of the variance in their biomass.
Lion tamarins (Callitrichidae: Leontopithecus) are small frugi-faunivores that defend large home ranges. We describe results from the first long-term investigation of wild golden-headed lion tamarins (L. chrysomelas; GHLTs). We present data about activity budgets, daily activity cycles, diet, daily path length, home range size, home range overlap, and territorial encounters for three groups of GHLTs that were studied for 1.5-2.5 years in Una Biological Reserve, Bahia State, Brazil, an area characterized by aseasonal rainfall. We compare our results to those from other studies of lion tamarins to identify factors that may influence foraging and ranging patterns in this genus. Ripe fruit, nectar, insects, and small vertebrates were the primary components of the GHLT diet, and gums were rarely eaten. Fruit comprised the majority of plant feeding bouts, and the GHLTs ate at least 79 different species of plants from 32 families. The most common foraging sites for animal prey were epiphytic bromeliads. The GHLTs defended large home ranges averaging 123 ha, but showed strong affinities for core areas, spending 50% of their time in approximately 11% of their home range. Encounters with neighboring groups averaged two encounters every 9 days, and they were always aggressive. Data about time budgets and daily activity cycles reveal that the GHLTs spent most of their time foraging for resources or traveling between foraging sites distributed throughout their home ranges. The GHLTs spent much less time consuming exudates compared to lion tamarins in more seasonal environments. Additionally, the GHLTs had much larger home ranges than golden lion tamarins (L. rosalia), and did not engage in territorial encounters as frequently as L. rosalia. GHLT ranging patterns appear to be strongly influenced by resource acquisition and, to a lesser extent, by resource defense.
The ecology of information use
- L A Giraldeau
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Habitat selection: patterns of spatial distribution from behavioural decisions
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Techniques for the Study of Pri-mate Population Ecology Conserving Biodiversity: A Re-search Agenda for Development Agencies Habitat alteration, hunting, and the conservation of folivorous primates in African forests
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Bamboo: Potential for Utilisation by the Commu-nities Surrounding Mt. Elgon National Park. Technical report. IUCN Country Office and Ministry of Natural Resources, Kampala. 592 Dennis Twinomugisha and Colin A. Chapman Ó 2007 The Authors
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- Dennis Twinomugisha
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Mgahinga Gorilla National Park Management Plan
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Bamboo: Potential for Utilisation by the Communities Surrounding Mt. Elgon National Park
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IUCN Country Office and Ministry of Natural Resources,
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