<p>Dots of each color show responses in each trial. The lowest observed proportion of visit... more <p>Dots of each color show responses in each trial. The lowest observed proportion of visiting young males was higher than the highest observed proportion of visiting bats that were female or adult male. Novel objects were always visited by more than five of the eight young males, whereas the other bats never visited a novel object.</p
Although a large body of primate cognition research is done in captive institutions, little is kn... more Although a large body of primate cognition research is done in captive institutions, little is known about how much individuals from different facilities vary in their experiences and cognitive skills. Here we present the results of an experimental study investigating how physical cognitive skills vary between chimpanzees in relation to captive settings and their time in captivity. We tested 59 chimpanzees housed at two different captive facilities (a rehabilitation center (sanctuary) and a zoo) in three problem-solving tasks. Our results showed that chimpanzees at the two housing facilities significantly differed in overall task performance. On average, the sanctuary chimpanzees outperformed the chimpanzees housed at the zoo in the detour reaching task and the honey trap task. However, the zoo chimpanzees performed slightly better on average in the learning task. We propose that, for this particular sample, the documented differences result from a combination of factors, such as pr...
Overview of the data used for the different analyses. Study site, focal individual, sex and date ... more Overview of the data used for the different analyses. Study site, focal individual, sex and date of birth of the focal individual, mother of the focal individual, as well as the years in which the different types of data (diet data, feeding rates, ramble ratios and laser measurements) were taken. Table S2. GLMM with absolute feeding rate of the adult females as dependent variable. To see if the if there is a difference between feeding rates obtained by video coding as opposed to direct observation this was included as as a binary variable ("Video"). Shown are effects, estimates, standard errors and p-values as well as number of levels for the categorical variables. The number in parentheses represents the total number of individual feeding rates included in the analyses: Only rates of fruits on which we had data from the same individual obtained via video coding as well as via direct observation were included. Table S3. GLMM with feeding rate in percentage of the mothers f...
Diet repertoire size in relation to follow effort: The number of recorded food items versus the n... more Diet repertoire size in relation to follow effort: The number of recorded food items versus the number of hours of follow data collected for the three adult females with the most data available at Tuanan. 500 follow hours correspond to roughly 1 year ( X ¯ $$ \overline{\mathrm{X}} $$ = 13.1 months), the overall observation time was 9.5 years. The total number of plant species recorded for each of these females was 109 – 113 ( X ¯ $$ \overline{\mathrm{X}} $$ =110.3). For insects we only counted termites, ants, bees (honey) and caterpillars as food items and did not distinguish between the different species. Thus, the number of non-plant food items was 4 for each adult female. Figure S2. Development of ramble ratios over age: Average daily ramble ratios versus age for immatures at Suaq and Tuanan. Figure S3. Body size comparisons: Estimated growth trajectories bases on forearm measurements for immatures at Suaq and Tuanan. The solid lines were attained via smoothing functions in R (s...
How animals react to novel situations, foods or objects reflects a balance between neophobia (nov... more How animals react to novel situations, foods or objects reflects a balance between neophobia (novelty avoidance) and neophilia — the drive to approach and explore, in other words components of curiosity. As such, animals behave according to the costs and benefits of exploring something new, potentially dangerous. In a new study in this issue of Current Biology, Ammie Kalan, Hjalmar Kühl and colleagues [1] report the behavioral responses of wild chimpanzees, bonobos and gorillas to camera traps. It is difficult to study reactions to novelty in the wild — usually this was thought to demand field experiments where one must be careful not to habituate wild populations, e.g. through food provisioning or through association with humans. Consequently, studies aiming to address curiosity should best avoid direct human observation. The use of video camera traps, applied by Kalan and colleagues [1], is a relatively non-invasive, yet effective approach to obtain genuine reactions to novel item...
The cognitive mechanisms causing intraspecific behavioural differences between wild and captive a... more The cognitive mechanisms causing intraspecific behavioural differences between wild and captive animals remain poorly understood. Although diminished neophobia, resulting from a safer environment and more “free” time, has been proposed to underlie these differences among settings, less is known about how captivity influences exploration tendency. Here, we refer to the combination of reduced neophobia and increased interest in exploring novelty as “curiosity”, which we systematically compared across seven groups of captive and wild vervet monkeys (Chlorocebus pygerythrus) by exposing them to a test battery of eight novel stimuli. In the wild sample, we included both monkeys habituated to human presence and unhabituated individuals filmed using motion-triggered cameras. Results revealed clear differences in number of approaches to novel stimuli among captive, wild-habituated and wild-unhabituated monkeys. As foraging pressure and predation risks are assumed to be equal for all wild mo...
The effects of age on neophobia and exploration are best described in birds and primates, and bro... more The effects of age on neophobia and exploration are best described in birds and primates, and broader comparisons require reports from other taxa. Here we present data showing age-dependent exploration in a long-lived social species, the common vampire bat (Desmodus rotundus). A previous study found that vampire bats regurgitated food to partners trapped in a cage. Interestingly, while only a few adult bats visited the trapped bat, in every trial all or most of the eight young males in the colony would visit the trapped bat without feeding it. To test whether this behavioral difference resulted from age class differences in exploration, we compared responses of the bats to a trapped conspecific versus an inanimate novel object. Some adults and young showed interest in trapped conspecifics, but only the young males explored the novel objects. Additional novel object tests in a second captive colony showed that higher rates of novel object exploration were shown by young of both sexes...
It has been hypothesized that opportunities for social learning affect the size and complexity of... more It has been hypothesized that opportunities for social learning affect the size and complexity of the adult skill set of birds and mammals, their learning ability, and thus ultimately also their innovation frequency. To test these predictions we compared rates of social learning, rates of independent exploration (independent learning) and innovation repertoires between individuals of a highly sociable population of Pongo abelii at Suaq Balimbing and a less sociable population of Pongo pygmaeus wurmbii at Tuanan. Suaq immatures showed significantly higher rates of peering, even after controlling for differences in association time and diet complexity, implying that they make disproportionally greater use of their increased opportunities for social learning. As predicted, we found that immatures and adults at Suaq also showed significantly higher rates of exploratory behaviour. The difference between the individuals of the two popuations remained when controlling for association time,...
Non-human animals sometimes show marked intraspecific variation in their cognitive abilities that... more Non-human animals sometimes show marked intraspecific variation in their cognitive abilities that may reflect variation in external inputs and experience during the developmental period. We examined variation in exploration and cognitive performance on a problem-solving task in a large sample of captive orang-utans (Pongo abelii & P. pygmaeus, N = 103) that had experienced different rearing and housing conditions during ontogeny, including human exposure. In addition to measuring exploration and cognitive performance, we also conducted a set of assays of the subjects’ psychological orientation, including reactions towards an unfamiliar human, summarized in the human orientation index (HOI), and towards novel food and objects. Using generalized linear mixed models we found that the HOI, rather than rearing background, best predicted both exploration and problem-solving success. Our results suggest a cascade of processes: human orientation was accompanied by a change in motivation tow...
<p>Dots of each color show responses in each trial. The lowest observed proportion of visit... more <p>Dots of each color show responses in each trial. The lowest observed proportion of visiting young males was higher than the highest observed proportion of visiting bats that were female or adult male. Novel objects were always visited by more than five of the eight young males, whereas the other bats never visited a novel object.</p
Although a large body of primate cognition research is done in captive institutions, little is kn... more Although a large body of primate cognition research is done in captive institutions, little is known about how much individuals from different facilities vary in their experiences and cognitive skills. Here we present the results of an experimental study investigating how physical cognitive skills vary between chimpanzees in relation to captive settings and their time in captivity. We tested 59 chimpanzees housed at two different captive facilities (a rehabilitation center (sanctuary) and a zoo) in three problem-solving tasks. Our results showed that chimpanzees at the two housing facilities significantly differed in overall task performance. On average, the sanctuary chimpanzees outperformed the chimpanzees housed at the zoo in the detour reaching task and the honey trap task. However, the zoo chimpanzees performed slightly better on average in the learning task. We propose that, for this particular sample, the documented differences result from a combination of factors, such as pr...
Overview of the data used for the different analyses. Study site, focal individual, sex and date ... more Overview of the data used for the different analyses. Study site, focal individual, sex and date of birth of the focal individual, mother of the focal individual, as well as the years in which the different types of data (diet data, feeding rates, ramble ratios and laser measurements) were taken. Table S2. GLMM with absolute feeding rate of the adult females as dependent variable. To see if the if there is a difference between feeding rates obtained by video coding as opposed to direct observation this was included as as a binary variable ("Video"). Shown are effects, estimates, standard errors and p-values as well as number of levels for the categorical variables. The number in parentheses represents the total number of individual feeding rates included in the analyses: Only rates of fruits on which we had data from the same individual obtained via video coding as well as via direct observation were included. Table S3. GLMM with feeding rate in percentage of the mothers f...
Diet repertoire size in relation to follow effort: The number of recorded food items versus the n... more Diet repertoire size in relation to follow effort: The number of recorded food items versus the number of hours of follow data collected for the three adult females with the most data available at Tuanan. 500 follow hours correspond to roughly 1 year ( X ¯ $$ \overline{\mathrm{X}} $$ = 13.1 months), the overall observation time was 9.5 years. The total number of plant species recorded for each of these females was 109 – 113 ( X ¯ $$ \overline{\mathrm{X}} $$ =110.3). For insects we only counted termites, ants, bees (honey) and caterpillars as food items and did not distinguish between the different species. Thus, the number of non-plant food items was 4 for each adult female. Figure S2. Development of ramble ratios over age: Average daily ramble ratios versus age for immatures at Suaq and Tuanan. Figure S3. Body size comparisons: Estimated growth trajectories bases on forearm measurements for immatures at Suaq and Tuanan. The solid lines were attained via smoothing functions in R (s...
How animals react to novel situations, foods or objects reflects a balance between neophobia (nov... more How animals react to novel situations, foods or objects reflects a balance between neophobia (novelty avoidance) and neophilia — the drive to approach and explore, in other words components of curiosity. As such, animals behave according to the costs and benefits of exploring something new, potentially dangerous. In a new study in this issue of Current Biology, Ammie Kalan, Hjalmar Kühl and colleagues [1] report the behavioral responses of wild chimpanzees, bonobos and gorillas to camera traps. It is difficult to study reactions to novelty in the wild — usually this was thought to demand field experiments where one must be careful not to habituate wild populations, e.g. through food provisioning or through association with humans. Consequently, studies aiming to address curiosity should best avoid direct human observation. The use of video camera traps, applied by Kalan and colleagues [1], is a relatively non-invasive, yet effective approach to obtain genuine reactions to novel item...
The cognitive mechanisms causing intraspecific behavioural differences between wild and captive a... more The cognitive mechanisms causing intraspecific behavioural differences between wild and captive animals remain poorly understood. Although diminished neophobia, resulting from a safer environment and more “free” time, has been proposed to underlie these differences among settings, less is known about how captivity influences exploration tendency. Here, we refer to the combination of reduced neophobia and increased interest in exploring novelty as “curiosity”, which we systematically compared across seven groups of captive and wild vervet monkeys (Chlorocebus pygerythrus) by exposing them to a test battery of eight novel stimuli. In the wild sample, we included both monkeys habituated to human presence and unhabituated individuals filmed using motion-triggered cameras. Results revealed clear differences in number of approaches to novel stimuli among captive, wild-habituated and wild-unhabituated monkeys. As foraging pressure and predation risks are assumed to be equal for all wild mo...
The effects of age on neophobia and exploration are best described in birds and primates, and bro... more The effects of age on neophobia and exploration are best described in birds and primates, and broader comparisons require reports from other taxa. Here we present data showing age-dependent exploration in a long-lived social species, the common vampire bat (Desmodus rotundus). A previous study found that vampire bats regurgitated food to partners trapped in a cage. Interestingly, while only a few adult bats visited the trapped bat, in every trial all or most of the eight young males in the colony would visit the trapped bat without feeding it. To test whether this behavioral difference resulted from age class differences in exploration, we compared responses of the bats to a trapped conspecific versus an inanimate novel object. Some adults and young showed interest in trapped conspecifics, but only the young males explored the novel objects. Additional novel object tests in a second captive colony showed that higher rates of novel object exploration were shown by young of both sexes...
It has been hypothesized that opportunities for social learning affect the size and complexity of... more It has been hypothesized that opportunities for social learning affect the size and complexity of the adult skill set of birds and mammals, their learning ability, and thus ultimately also their innovation frequency. To test these predictions we compared rates of social learning, rates of independent exploration (independent learning) and innovation repertoires between individuals of a highly sociable population of Pongo abelii at Suaq Balimbing and a less sociable population of Pongo pygmaeus wurmbii at Tuanan. Suaq immatures showed significantly higher rates of peering, even after controlling for differences in association time and diet complexity, implying that they make disproportionally greater use of their increased opportunities for social learning. As predicted, we found that immatures and adults at Suaq also showed significantly higher rates of exploratory behaviour. The difference between the individuals of the two popuations remained when controlling for association time,...
Non-human animals sometimes show marked intraspecific variation in their cognitive abilities that... more Non-human animals sometimes show marked intraspecific variation in their cognitive abilities that may reflect variation in external inputs and experience during the developmental period. We examined variation in exploration and cognitive performance on a problem-solving task in a large sample of captive orang-utans (Pongo abelii & P. pygmaeus, N = 103) that had experienced different rearing and housing conditions during ontogeny, including human exposure. In addition to measuring exploration and cognitive performance, we also conducted a set of assays of the subjects’ psychological orientation, including reactions towards an unfamiliar human, summarized in the human orientation index (HOI), and towards novel food and objects. Using generalized linear mixed models we found that the HOI, rather than rearing background, best predicted both exploration and problem-solving success. Our results suggest a cascade of processes: human orientation was accompanied by a change in motivation tow...
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