Neurobiological and Ecological Correlates of Avian Innovation

Songbird species that display more-complex vocal learning are better problem-solvers and have larger brains

Complex vocal learning, a critical component of human spoken language, has been assumed to be associated with more-advanced cognitive abilities. Tests of this hypothesis between individuals within a species have been inconclusive and have not been done across species. In this work, we measured an array of cognitive skills-namely, problem-solving, associative and reversal learning, and self-control-across 214 individuals of 23 bird species, including 19 wild-caught songbird species, two domesticated songbird species, and two wild-caught vocal nonlearning species. We found that the greater the vocal learning abilities of a species, the better their problem-solving skills and the relatively larger their brains. These conclusions held when controlling for noncognitive variables and phylogeny. Our results support a hypothesis of shared genetic and cognitive mechanisms between vocal learning, problem-solving, and bigger brains in songbirds.

Foraging on anthropogenic food predicts problem-solving skills in a seabird

Species and populations with greater cognitive performance are more successful at adapting to changing habitats. Accordingly, urban species and populations often outperform their rural counterparts on problem-solving tests. Paradoxically, urban foraging also might be detrimental to the development and integrity of animals' brains because anthropogenic foods often lack essential nutrients such as the long-chain omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are important for cognitive performance in mammals and possibly birds. We tested whether urbanization or consumption of EPA and DHA are associated with problem-solving abilities in ring-billed gulls, a seabird that historically exploited marine environments rich in omega-3 fatty acids but now also thrives in urban centres. Using incubating adults nesting across a range of rural to urban colonies with equal access to the ocean, we tested whether urban gulls preferentially consumed anthropogenic food while rural nesters relied on marine organisms. As we expected individual variation in foraging habits within nesting location, we characterized each captured gulls' diet using stable isotope and fatty acid analyses of their red blood cells. To test their problem-solving abilities, we presented the sampled birds with a horizontal rendition of the string-pull test, a foraging puzzle often used in animal cognitive studies. The isotopic and fatty acid profiles of urban nesters indicated a diet comprising primarily anthropogenic food, whereas the profiles of rural nesters indicated a high reliance on marine organisms. Despite the gulls' degree of access to urban foraging habitat not predicting solving success, birds with biochemical profiles reflecting anthropogenic food (less DHA and a higher carbon-13 ratio in their red blood cells) had a greater probability of solving the string-pull test. These results suggest that experience foraging on anthropogenic food is the main explanatory factor leading to successful problem-solving, while regular consumption of omega-3s during incubation appears inconsequential.

Integrative Comparative Cognition: Can Neurobiology and Neurogenomics Inform Comparative Analyses of Cognitive Phenotype?

A long-standing question in animal behavior is what are the patterns and processes that shape the evolution of cognition? One effective way to address this question is to study cognitive abilities in a broad spectrum of animals. While comparative psychologists have traditionally focused on a narrow range of organisms, today they may work with any number of species, from frogs to birds or bees. This broader range of study species has greatly enriched our understanding of the diversity of cognitive processes among animals. Yet, this diversity has highlighted the fundamental challenge of comparing cognitive processes across animals. An analysis of the neural and molecular mechanisms of cognition may be necessary to solve this problem. The goal of our symposium was to bring together speakers studying a range of species to gain a broadly integrative perspective on cognition while at the same time considering the potentially important role of neurobiology and genomics in addressing the difficult problem of comparing cognition across species. For example, work by MaBouDi et al. indicates that neural constraints on computing power may impact the cognitive processes underlying numerical discrimination in bees. A presentation by Lara LaDage demonstrated how neurobiology can be used to better understand cognition and its evolution in reptiles while Edwards et al. identify the cerebellum as potentially important in the performance of the complex process of nest building. We see that molecular approaches highlight the contributions of the prefrontal cortex and hippocampus to cognitive phenotype across vertebrates while, at the same time, identifying the genes and cellular processes that may contribute to evolution of cognition. The potentially important role of neurogenesis and synaptic plasticity emerge clearly from such studies. Still unanswered is the question of whether molecular tools will contribute to our ability to discriminate convergent/parallel evolution from homology in the evolution of cognitive phenotype.