Analogical reasoning is vital to advanced cognition and behavioral adaptation. Many theorists deem analogical thinking to be uniquely human and to be foundational to categorization, creative problem solving, and scientific discovery. Comparative psychologists have long been interested in the species generality of analogical reasoning, but they initially found it difficult to obtain empirical support for such thinking in nonhuman animals (for pioneering efforts, see [2, 3]). Researchers have since mustered considerable evidence and argument that relational matching-to-sample (RMTS) effectively captures the essence of analogy, in which the relevant logical arguments are presented visually. In RMTS, choice of test pair BB would be correct if the sample pair were AA, whereas choice of test pair EF would be correct if the sample pair were CD. Critically, no items in the correct test pair physically match items in the sample pair, thus demanding that only relational sameness or differentness is available to support accurate choice responding. Initial evidence suggested that only humans and apes can successfully learn RMTS with pairs of sample and test items; however, monkeys have subsequently done so. Here, we report that crows too exhibit relational matching behavior. Even more importantly, crows spontaneously display relational responding without ever having been trained on RMTS; they had only been trained on identity matching-to-sample (IMTS). Such robust and uninstructed relational matching behavior represents the most convincing evidence yet of analogical reasoning in a nonprimate species, as apes alone have spontaneously exhibited RMTS behavior after only IMTS training.

Two juvenile orange-winged amazons (Amazona amazonica) were initially trained to match visual stimuli by color, shape, and number of items, but not by size. After learning these three identity matching-to-sample tasks, the parrots transferred discriminative responding to new stimuli from the same categories that had been used in training (other colors, shapes, and numbers of items) as well as to stimuli from a different category (stimuli varying in size). In the critical testing phase, both parrots exhibited reliable relational matching-to-sample (RMTS) behavior, suggesting that they perceived and compared the relationship between objects in the sample stimulus pair to the relationship between objects in the comparison stimulus pairs, even though no physical matches were possible between items in the sample and comparison pairs. The parrots spontaneously exhibited this higher-order relational responding without having ever before been trained on RMTS tasks, therefore joining apes and crows in displaying this abstract cognitive behavior.

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A set of string pulling tasks was used to compare the cognitive abilities of birds with different levels of brain complexity, which was judged using Portmann's index for the hemispheres. Varying the number and relative position of strings and bait, we investigated whether birds of different species (hooded crows (Corvus cornix), red crossbills (Loxia curvirostra), Eurasian blue tits (Parus caeruleus), and great gray owls (Strix neb ulosa)) are capable of comprehending the logical structure of such tasks based on cause-effect relationships. Among the observed representatives of Passeriformes, only hooded crows, which possess the most complex and highly differentiated brain, were shown to be able to solve correctly the most difficult versions of the string pulling tasks and, therefore, to understand their logical structure. Small passerine birds and owls, which are characterized by a similarly high value of Portmann's index, proved to be incapable of compre hending the cause-effect relationship between the components of the tasks.

Cognitive abilities of the Great Grey Owl (Strix nebulosa) were tested with a means–end problem. Owls were presented the single baited string task and the string discrimination task. Our results suggest that owls failed to comprehend the physics underlying the object relationships involved in the tasks presented

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The ability of the Glaucous-winged Gull (Larus glaucescens) to observationally learn has been investigated in their natural habitat, in a gull's colony located on Toporkov Island (Comandorsky State Nature Reserve, Far East, Russia). The experiment was carried out in the gull's breeding period, when each bird's pair in the colony occupies and protects vigilantly their small nesting sites surrounded by those of neighboring pairs. The gulls chosen to be demonstrators were trained to solve two different tasks both of which were not part of the species' behavioral repertoire. The first task was obtaining a bait placed by an experimenter into an opaque box within the bird's visual field; the second one was choosing a red box from a set of four identically-looking boxes differing only in color. In contrast to the demonstrator gulls, which needed considerably training, most observers (the gulls nesting side-by-side with the demonstrators) performed the same tasks correctly in the first trial. Thus, gulls have proven to be capable of successful learning to solve simple choice tasks by observing what their conspecifics are doing. Observational learning can be a way to distribute individual experience among the gulls in a colony. The ability to observationally learn quickly may be one of the factors underlying a higher adaptive potential of these birds.