Western lowland gorillas (Gorilla gorilla gorilla) change their activity patterns in response to frugivory

Abstract

The most important environmental factor explaining interspecies variation in ecology and sociality of the great apes is likely to be variation in resource availability. Relatively little is known about the activity patterns of western lowland gorillas (Gorilla gorilla gorilla), which inhabit a dramatically different environment from the well-studied mountain gorillas (G. beringei beringei). This study aims to provide a detailed quantification of western lowland gorillas' activity budgets using direct observations on one habituated group in Bai Hokou, Central African Republic. We examined how activity patterns of both sexes are shaped by seasonal frugivory. Activity was recorded with 5-min instantaneous sampling between December 2004 and December 2005. During the high-frugivory period the gorillas spent less time feeding and more time traveling than during the low-frugivory period. The silverback spent less time feeding but more time resting than both females and immatures, which likely results from a combination of social and physiological factors. When compared with mountain gorillas, western lowland gorillas spend more time feeding (67 vs. 55%) and traveling (12 vs. 6.5%), but less time resting (21 vs. 34%) and engaging in social/other activities (0.5 vs. 3.6%). This disparity in activity budgets of western lowland gorillas and mountain gorillas may be explained by the more frugivorous diet and the greater dispersion of food resources experienced by western lowland gorillas. Like other apes, western lowland gorillas change their activity patterns in response to changes in the diet.

Differences in the Activity Budgets of Yunnan Snub-Nosed Monkeys (Rhinopithecus bieti) by Age-Sex Class at Xiangguqing in Baimaxueshan Nature Reserve, China

“…As observed in several other primate species [Clutton-Brock, 1977;Masi et al, 2009], the activity budgets of R. bieti varied among age-sex classes at Xiangguqing. In this study, adult females spent more time feeding and resting than either males or juveniles.…”

Temporal variation selects for diet–microbe co-metabolic traits in the gut of Gorilla spp

“…Lowland gorillas experience important dietary limitations when ripe fruit is not immediately available. That is, seasonal shifts in their habitat forces them to rely mainly on fibrous fruits, leaves and herbaceous vegetation during the low ripe fruit season (Masi et al, 2009). These fibrous foods are low in readily digestible energy, higher in hemicellulose, cellulose and lignin than ripe fruit (Remis, 1997a,b,c Remis et al, 2001Rogers et al, 2004Rogers et al, ,1990Rothman et al, 2014), although in times of fruit scarcity fruits eaten are high in fiber and similar to vegetation (Remis et al, 2001).…”

“…(Remis, 1997a;Doran and McNeilage, 1998). In contrast, the fragmented distribution of fruit and the higher nutritional diversity of fruit substrates expand foraging options in gorilla groups, causing individuals within groups to consume more diverse diets when fruit is available (Masi et al, 2009;Rogers et al, 2004). This is an interesting example of how macroecological patterns may be also reflected at microecological scales.…”

“…G. g. gorilla experience marked shifts in the availability of preferred resources yearlong (Rogers et al, 2004); they spend about 80% of their time consuming readily digestible fruit when seasonally available, but shift to a similar percent of time feeding on vegetation (terrestrial herbs and leaves) in drier periods of the year (Masi, 2007;Masi et al, 2009), while also incorporating fibrous fruit and bark (Remis, 1997b).…”

Les gorilles du Parc National de Lobéké (Cameroun): interactions avec les populations locales et implications pour la conservation

“…En effet, pendant la période de fructification (entre les mois de mai et août), les gorilles sont retranchés en forêt pour s'en approvisionner. Les gorilles de plaine de l'ouest étant essentiellement frugivores (Hockings et Humle, 2009), il existe une relation entre les attaques de gorille et la présence des fruits en forêt (Masi et al, 2009). Les villageois quant à eux s'installent aussi en forêt pour le ramassage des fruits dont le plus sollicité est Irvingia gabonensis.…”