Effect of repeated exposures and sociality on novel food acceptance and consumption by orangutans

Abstract

Hundreds of rehabilitant great apes have been released into the wild, and thousands await release. However, survival rates after release can be as low as 20%. Several factors influence individuals' survival rates, one of which is the capacity to obtain an adequate diet once released. Released individuals are faced with a mixture of familiar and novel foods in an unfamiliar forest; therefore, it is important to understand how they increase acceptance and consumption of novel foods. This is especially vital for omnivorous species, such as wild great apes, which consume several hundred species of different foods. We assessed the effects of repeated exposures and sociality (i.e. co-feeding in the presence of one or more other individuals) on the acceptance and consumption of novel foods by captive orangutans (Pongo sp). Repeated exposures of food (novel, at first) did not cause an increase of acceptance of food; in other words, the orangutans did not start to eat a food item after being exposed to that food more often, but repeated exposures of food increased consumption (i.e. quantity). After repeated exposures, the orangutans also became gradually more familiar with the food, decreasing their explorative behaviour. The presence of co-feeding conspecifics resulted in an increased acceptance of the novel food by orangutans, and they ate a larger amount of said foods than when alone. Repeated exposure and sociality may benefit rehabilitant great apes in augmenting and diversifying diet and, once practiced before release, may accelerate an individuals' adaptation to their new habitat, improving survival chances. Great ape rescue, rehabilitation and reintroduction require large financial and logistic investments; however, their effectiveness may be improved at low cost and low effort through the suggested measures.

The reluctant innovator: orangutans and the phylogeny of creativity

“…Similar observations are reported for other mammals [72] and birds [73,74], as well as for captive primates [75]. Second, experiments show that naive individuals lose their neophobia when accompanied or provisioned by others, who may or may not be more knowledgeable [76][77][78], a finding replicated among orangutans [62,79].…”

Captive chimpanzee foraging in a social setting: a test of problem solving, flexibility, and spatial discounting

“…Many primates live in social groups and so an individual’s foraging strategy and food choices may also be influenced by the decisions and preferences of its group mates as well as the effort required to obtain that food ( Finestone et al, 2014 ; Hardus et al, 2015 ; Marshall et al, 2015 ). Indeed, an advantage of social living for gregarious primate species is that they can use social information to learn where to find food ( Rapaport & Brown, 2008 ), which foods to eat ( Visalberghi & Addessi, 2000 ; van de Waal, Borgeaud & Whiten, 2013 ), and how to process those foods ( Boinski & Timm, 1985 ; van de Waal, Bshary & Whiten, 2014 ).…”

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“…We did not find that individuals reversed their food preferences in the presence of higher-ranking group members, nor that the presence of other conspecifics affected individuals' preference for familiar over novel food (model M1, full-null not significant, Table 2). This result seems to be in contrast with other studies showing that the presence of a conspecific facilitates the acceptance of novel food in primates Addessi, 2000, 2001;Addessi and Visalberghi, 2001;Addessi et al, 2007;Hardus et al, 2015;Englerova et al, 2019). In these studies, however, conspecifics were not directly in contact with the focal subject (i.e., they had only visual but not physical contact).…”

“…Moreover, it would be interesting to use a larger variety of novel stimuli, to systematically address how primates generalize previous experience and novelty depending on the specific characteristics of the stimuli they are exposed to. A better understanding of how animals respond to novelty will provide us with crucial information about their ability to respond to novel socioecological challenges and, importantly, it will have ethical implications, by contributing to improve the welfare of captive animals (Buchanan-Smith, 2011), to increase the effectiveness of reintroduction programs (Hardus et al, 2015), and to carry out more effective conservation programs in habitats where rapid environmental changes arise (e.g., in deforested or urbanized environments; McLennan et al, 2017) resulting in animals facing more frequently the necessity to switch over novel food sources for their survival.…”

“…Therefore, higher-ranking or more socially-integrated individuals may receive a lower potential payoff from novel stimuli, and may be more neophobic than lower-ranking or less socially-integrated individuals (Hegner, 1985;Greenberg-Cohen et al, 1994;Lahti, 1998;Wolf et al, 2007;An et al, 2011). Furthermore, in some species the presence of a conspecific may facilitate the acceptance of novel food or objects (birds: Coleman and Mellgren, 1994;Huber et al, 2001;rodents: Forkman, 1991;canids: Moretti et al, 2015;primates: Visalberghi and Addessi, 2000;Voelkl et al, 2006;Hardus et al, 2015). The latter findings may result from very different processes.…”