No abstract

Problem solving often relies on generating new responses while inhibiting others, particularly prepotent ones. A paradigm to study inhibitory abilities is the reverse contingency task (Boysen and Berntson in J Exp Psychol Anim Behav Process 21:82-86, 1995), in which two different quantities of food are offered to an individual who receives the array he did not choose. Therefore, mastery of the task demands selecting the smaller quantity to obtain the larger one. Several non-human primates have been tested in the reverse contingency task. To date, only great apes and rhesus monkeys (Macaca mulatta) have succeeded in the original task, with no need of procedural modifications as the large-or-none contingency, correction trials or symbolic stimuli substituting for actual food quantities. Here, four mangabeys were presented with two stimulus arrays of one and four raisins in the context of the reverse contingency task. Three of them learned to perform the task well above chance without a modified procedure. They also reached above-chance performance when presented with two stimulus arrays of zero and four raisins, despite the initial difficulty of choosing a null quantity. After a period of 7-10 months, in which the animals were not tested on any task, all three subjects continued to perform well, even when presented with novel quantity pairs.

Zoo visitors perceive naturalistic enclosures (i.e. those attempting to replicate identifiable parts of the landscape of the species' habitat) as those that best satisfy the biological needs of the animals, and ensure therefore their welfare. However, the provision of a suitable environment with the resources that will allow the animals to satisfy their main biological needs in naturalistic enclosures has never been systematically explored; instead, it has been assumed. In this study we provide evidence that supports the general idea that naturalistic designs provide suitable environments for the animals. For that purpose, we analyzed 1,381 naturalistic and non-naturalistic enclosures in 63 Spanish zoological parks. In order to assess the suitability of the environment provided within each enclosure, a number of aspects related to the animals' main biological requirements were analyzed. We found a relationship between naturalistic designs and the suitability of the environment for the species housed. Most naturalistic enclosures (77.8%) provided suitable environments for their inhabitants. Non-naturalistic ones also had suitable environments, but in a lower percentage (39.7%). These results should be taken into account during zoo inspection and accreditation appointments, where enclosure suitability must be assessed in an accurate and fast manner. In this regard, a naturalistic design can be used as an adjunct indicator of enclosure suitability, but not exclusively, as not every naturalistic enclosure was suitable for the animals, neither as an indispensable one, given that near 40% of non-naturalistic ones were appropriate for the species housed.

The authors examine the relative roles of vision and chemoreception and the influence of previous experience with prey on the predatory behavior of Iberian wall lizards (Podarcis hispanica). Experiment 1 compared the responses to visual, chemical, and a combination of visual and chemical cues of a familiar prey by 2 groups of lizards that had been kept in captivity for either 3 months or 21 days. Experiment 2 assessed the responses of lizards kept in the laboratory for more than 3 months to a novel prey species. The results reveal that feeding on a prey species affects the lizards' responses to chemical stimuli from that prey. The response to chemical cues of a novel prey requires a 1st-feeding experience with that prey. Lizards that have been fed the same prey species for several months cease responding to the chemical stimuli of that particular prey.

Although play fighting has been studied for over a century in both human and non‐human animals, quantitative data on marine mammals are still scarce. Here, we investigated play fighting in South American sea lions (Otaria flavescens), one of the most sexually dimorphic species with an extreme polygynous mating system, high levels of both intra‐ and inter‐sexual competition. All these features make South American sea lions a good model species to test some predictions on play fighting. Our results indicate play is restricted to juveniles, being inhibited among adults, and as to be expected in a species that shows a high degree of sexual dimorphism, it is mainly expressed in males. Even though playful interactions were punctuated by competitive behaviours, animals played in a highly symmetric way and were able to adjust their competitive playful interactions in a flexible manner and so reduce the risk of escalation to a minimum level. They were highly selective in their choice of playmates by limiting the number of players per session and playing more with age‐matched companions and friends. All these factors taken together are probably at the basis of the low risk of escalation recorded during the study. This result is predictive of a high ability and motivation of these animals to engage in play behaviour which can have a possible role not only in the acquisition of dominance status, but also in establishing and maintaining social relationships, an unexpected role in a so highly competitive species.