Abstract: Abstract  Both in captivity and the wild, primates are found to travel mostly to the nearest available resource, but they may skip over the closest resource and travel to more distant resources, which are often found to be more productive. This study examines the tradeoff between distance and reward in the foraging choices of one group of wild capuchin monkeys (Cebus apella nigritus) using feeding platforms in large-scale foraging experiments conducted over four years. Three feeding sites were arrayed in an oblique triangle, such that once the monkey group had chosen one site to feed, they had a choice between two remaining sites, a close one with less food and the other up to 2.3 times as far away but with more food. Sites were provisioned once per day. The capuchins generally chose the closer feeding site, even when the more distant site offered up to 12 times as much food. The distances to, rewards of, or various profitability measures applied to each alternative site individually did not explain the groups choices in ways consistent with foraging theory or principles of operant psychology. The groups site choices were predicted only by comparing efficiency measures of entire foraging pathways: (1) direct travel to the more rewarding distant site, versus (2) the longer “detour” through the closer site on the way to the more distant one. The group chose the detour more often when the reward was larger and the added detour distance shorter. They appeared to be more sensitive to the absolute increase in detour distance than to the relative increase compared to the straight route. The qualitative and quantitative results agree with a simple rule: do not use the detour unless the energy gain from extra food outweighs the energy cost of extra travel. These results suggest that members of this group integrate information on spatial location, reward, and perhaps potential food competition in their choice of multi-site foraging routes, with important implications for social foraging.

Abstract: Although it is well known that frugivorous spider monkeys (Ateles geoffroyi yucatanensis) occupy large home ranges, travelling long distances to reach highly productive resources, little is known of how they move between feeding sites. A 11 month study of spider monkey ranging patterns was carried out at the Otochma’ax Yetel Kooh reserve, Yucatán, Mexico. We followed single individuals for as long as possible each day and recorded the routes travelled with the help of a GPS (Global Positioning System) device; the 11 independently moving individuals of a group were targeted as focal subjects. Travel paths were composed of highly linear segments, each typically ending at a place where some resource was exploited. Linearity of segments did not differ between individuals, and most of the highly linear paths that led to food resources were much longer than the estimate visibility in the woodland canopy. Monkeys do not generally continue in the same ranging direction after exploiting a resource: travel paths are likely to deviate at the site of resource exploitation rather than between such sites. However, during the harshest months of the year consecutive route segments were more likely to retain the same direction of overall movement. Together, these findings suggest that while moving between feeding sites, spider monkeys use spatial memory to guide travel, and even plan more than one resource site in advance.

Abstract: Abstract  Most studies of spatial memory in primates focus on species that inhabit large home ranges and have dispersed, patchy resources. Researchers assume that primates use memory to minimize distances traveled between resources. We investigated the use of spatial memory in a group of six white-faced sakis (Pithecia pithecia) on 12.8-ha Round Island, Guri Lake, Venezuela during a period of fruit abundance. The sakis movements were analyzed with logistic regressions, a predictive computer model and a computer model that simulates movements. We considered all the resources available to the sakis and compared observed distances to predicted distances from a computer model for foragers who know nothing about the location of resources. Surprisingly, the observed distances were four times greater than the predicted distances, suggesting that the sakis passed by a majority of the available fruit trees without feeding. The odds of visiting a food tree, however, were significantly increased if the tree had been visited in the previous 3 days and had more than 100 fruit. The sakis preferred resources were highly productive fruit trees, Capparis trees, and trees with water holes. They traveled efficiently to these sites. The sakis choice of feeding sites indicate that they combined knowledge acquired by repeatedly traveling through their home range with “what” and “where” information gained from individual visits to resources. Although the sakis foraging choices increased the distance they traveled overall, choosing more valued sites allowed the group to minimize intragroup feeding competition, maintain intergroup dominance over important resources, and monitor the state of resources throughout their home range. The sakis foraging decisions appear to have used spatial memory, elements of episodic-like memory and social and nutritional considerations.

Abstract: At the beginning of the twentieth century, behaviourists like John B. Watson (1878-1958) changed the focus of attention from the inside of the brain (mentalism and introspection then being the main trend in psychology at the time) to the outside (Watson, 1913). They believed that we could learn nearly everything about animals and humans by studying their performance in learning experiments, and this was both measurable and verifiable. Today in the first decade of the twenty-first century, there has been a return to the inside. The neurosciences seek physiological explanations and connections between external behaviour and the neural mechanisms within the nervous system. With the revolution in magnetic resonance imaging (MRI) technology researchers are now able to visually represent neural activity. Other researchers have developed mathematical models and programs to visualise the patterns created in the periphery prior to central integration The author in this paper would like to distinguish these descriptive forms of representation from actual representations, i.e., those of which the animal is actually aware or conscious. Why does an animal sometimes make perceptual mistakes? (Case Study I “The Turtle and the Plastic Bag”). Is there more to dispositions? (Case Study II: “Taking Representation for a Walk. Argos and the Fake Daniel Dennett”). How is prey represented to an animal? (Case Study III “Representation of Prey in the Jellyfish/Herring Predator-Prey Dyad”). Does a simple animal feel pain or suffer? (Case Study IV: A Can of Worms. The Earthworm as Bait) It will be argued on the basis of contemporary biosemiotic research that animals (including both vertebrates and invertebrates) represent environmental information internally, and these representations can be subdivided into i.) primary or peripheral representation and ii.) central representation which are quantitative and qualitative respectively. Sensory information is conveyed via signals, these are received as stimuli then transduced into internal signals (see Theoretical Framework). At this stage the animal is not aware of the quality of the information as it has not yet been integrated or processed in a ganglionic complex. One can describe the properties of this pre-integrated information as quantitative and syntactical i.e., spatial and temporal ordering of incoming signals and their relations. The sign which is the smallest unit of qualitative representation arises only after integration of information from two or more discrete sensory modalities. These findings have repercussions for current models of animal learning and behaviour, especially in lower invertebrates (the principal subject of this paper); they also challenge the development of robots based on so-called simple systems