Ranging behavior of the mountain gorillas (Gorilla beringei beringei) in Bwindi Impenetrable National Park, Uganda: a test of the ecological constraints model

Ganas, Jessica; Robbins, Martha M.

doi:10.1007/s00265-005-0920-z

Cited by 141 publications

(113 citation statements)

References 95 publications

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“…Although we have not compared levels of feeding competition across species (as in Janson and Goldsmith 1995), this research nevertheless suggests that at least some folivores may be food-limited and experience potentially group size limiting within-group scramble competition in ways similar to that of frugivores. Recent studies have come to similar conclusions, but for less folivorous primates, or those with larger group sizes (Ganas and Robbins 2005;Snaith and Chapman 2005;Borries et al 2008;Snaith and Chapman 2008;Teichroeb and Sicotte 2008). Furthermore, this study improves on previous research by investigating the physiological costs that may accompany reduced food availability and/or increased feeding competition.…”

supporting

confidence: 63%

Small folivorous primate groups exhibit behavioral and physiological effects of food scarcity

Harris¹,

Chapman²,

Monfort³

2009

Behavioral Ecology

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The influence of diet and food distribution on the socioecology of group-living species has long been debated, particularly for primates. It has typically been assumed that folivorous primates experience relatively little feeding competition due to the abundant, widespread nature of their food, freeing them to form large groups in response to predation, to disperse with relative ease, and to have egalitarian female social relationships. Recent studies, however, have come to different conclusions about the extent to which folivorous primates are limited by food and experience food competition and how these factors affect folivore socioecology. To better understand the selective pressures that diet places on folivores, we investigated how 2 small highly folivorous groups of colobus monkeys (Colobus guereza) in Kibale National Park, Uganda, responded behaviorally and physiologically to a steep reduction in availability of their most important foods. The monkeys decreased their reliance on their 2 most frequently eaten food species and increased their daily path length, number of feeding patches visited/day, size of individual feeding areas, percentage of time spent feeding, and dietary diversity. They also showed evidence of physiological costs, in that lactating females' urinary C-peptide levels (i.e., insulin production) declined as top foods became scarce, and parasite loads slightly, but significantly, increased in 2 of 3 adult females examined. These results suggest that highly folivorous primates, even in very small groups, may experience behavioral and physiological effects of food limitation, within-group scramble competition for food, and possibly substantial selective pressures during periods of food scarcity.

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supporting

confidence: 63%

Small folivorous primate groups exhibit behavioral and physiological effects of food scarcity

Harris¹,

Chapman²,

Monfort³

2009

Behavioral Ecology

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“…Further evidence for scramble competition in Bwindi gorillas is that daily travel distance increased as both group size and frugivory increased (Ganas and Robbins 2005). In contrast, Karisoke mountain gorillas, which feed upon abundant, evenly distributed herbaceous vegetation, show little or no evidence of the costs of scramble competition because mean day journey length (DJL) was relatively constant over a wide range of group sizes (Watts 1998) and group size had no effect on female reproductive success ).…”

Section: Discussionmentioning

confidence: 99%

“…However, the observations were only in a bai (a large swampy clearing) where the gorillas feed solely on highly abundant, evenly distributed herbaceous vegetation. Researchers have reported no dominance hierarchy for the Bwindi mountain gorillas, but Ganas and Robbins (2005) found that they traveled further on days when they ate fruit than on days when they did not. In addition, they found a positive relationship between group size and both daily travel distance and home range size, suggesting that food distribution and availability, in particular that of fruit, may lead to increased levels of intragroup scramble competition at Bwindi.…”

Section: Introductionmentioning

confidence: 99%

Feeding Competition and Agonistic Relationships Among Bwindi Gorilla beringei

Robbins

2008

Int J Primatol

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Testing predictions of socioecological models, specifically that the types of feeding competition and social relationships female primates exhibit are strongly influenced by the distribution, density, and quality of food resources, requires studies of closely related populations of subjects living under different ecological conditions. I examined feeding competition and the resulting female social relationships in mountain gorillas (Gorilla beringei beringei) of Bwindi Impenetrable National Park, Uganda, which has ecological conditions distinctive from those where other gorilla populations live. I observed 1 group of gorillas for 29 mo to examine the proportion of time spent foraging on fruit, the relationship between patch size and occupancy patterns of fruit trees, and agonistic interactions. Patch occupancy time while foraging in fruit trees decreased with increasing number of gorillas in a tree and decreasing tree size, suggesting that fruit trees represent limiting patches and can lead to intragroup scramble competition. Gorillas exhibited higher levels of aggression while feeding on fruit versus other food resources, which indicates intragroup contest competition. I observed a linear dominance hierarchy with no bidirectionality via displacements, and a similar hierarchy via aggression, though a notable proportion of the dyads contained 2-way interactions. However, most aggression was of low intensity (vocalizations) and the recipient typically ignored it. Despite differences in ecological conditions and diet between the Virunga Volcanoes and Bwindi, agonistic relationships among females are largely similar in the 2 populations and are best characterized as dispersal individualistic.

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“…Other studies reported were merely on the comparison of the home range size of two or more groups in the same habitat (Ahsan 2004). While among the other gibbon species of Southeast Asia, Lar Gibbon is the most studied (Raemaekers 1979;Bartlett 1999Bartlett , 2009) followed by Kloss's Gibbon (e.g., Whitten 1982) and others (e.g., Ganas & Robbins 2005;Zhou et al 2007;Kim et al 2011). A few studies were carried out on the genus Hoolock to document its ranging pattern in Bangladesh, China and India Ahsan 2001;Kakati 1997Kakati , 2004Das 2002;Fan et al 2013), although the range use pattern of H. leuconedys has not been studied in India earlier.…”

Section: Introductionmentioning

confidence: 99%

The day range and home range of the Eastern Hoolock Gibbon Hoolock leuconedys (Mammalia: Primates: Hylobatidae) in Lower Dibang Valley District in Arunachal Pradesh, India

Sarma

Kumar

2016

J. Threat. Taxa

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This paper presents the findings of a study conducted on the Eastern Hoolock Gibbon Hoolock leuconedys in Mehao Wildlife Sanctuary and outside to the south of the park, Arunachal Pradesh, India investigating the daily path length (DPL) and home range used by the species in two forest areas with different disturbance gradients. The four habituated groups of H. leuconedys in fragmented and contiguous forest areas, two groups in each of the forest types, showed considerable variation in their DPL ranging from 6.59m to 1019.01m with a mean distance of 192.75m (SE = ±26.48) in 73 full day observations. Although the mean DPL was recorded with very little variation across the seasons in both the forest types, it was significantly different from fragmented forest. Similarly, the home range size also varied among the groups and was estimated as the maximum for Group D (24.62ha) followed by Group E (16.28ha) in contiguous forest and Group B (2.49ha) and Group A (1.09ha) in fragmented forest. Also, there was a distinct seasonal pattern of home range used by all the study groups with largest seasonal home range in monsoon and pre-monsoon season in fragmented and contiguous forest respectively. The DPL and home range of H. leuconedys in Arunachal Pradesh has been highly affected by forest fragmentation and/or canopy discontinuity which makes the species vulnerable to hunting, predation by feral dogs and hawks and ultimately local extinction. Thus, the findings of the present research evoke the question of long term survival of the species in fragmented forests.

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Ranging behavior of the mountain gorillas (Gorilla beringei beringei) in Bwindi Impenetrable National Park, Uganda: a test of the ecological constraints model

Cited by 141 publications

References 95 publications

Small folivorous primate groups exhibit behavioral and physiological effects of food scarcity

Small folivorous primate groups exhibit behavioral and physiological effects of food scarcity

Feeding Competition and Agonistic Relationships Among Bwindi Gorilla beringei

The day range and home range of the Eastern Hoolock Gibbon Hoolock leuconedys (Mammalia: Primates: Hylobatidae) in Lower Dibang Valley District in Arunachal Pradesh, India

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