Thought for food; brain activity and task performance of American crows (Corvus brachyrhynchos) in pursuit of food

Abstract

The last common ancestor shared by modern birds and mammals died out over 300 million years ago, yet both groups have convergently evolved more advanced intelligence than any other taxonomic class. With their enlarged forebrains, behavioral flexibility, and ability to navigate novel challenges in their environment, members of the Corvidae family are often compared to primates, yet we know considerably less about corvid intelligence than we do primate intelligence. In this dissertation, I explore the intelligence and brain activity of American crows (Corvus brachyrhynchos) as they pursue a food reward. First, I examine the individual and social factors which influence crows’ ability to solve and master a string-pulling task. Although not statistically significant, I find that crows with large brain volumes and without a conspecific model consistently mastered the task in the minimum number of days, whereas those with conspecific models and smaller brain volumes required varying and sometimes a substantial number of days to master the task. Second, I work with the UW Department of Radiology to examine crow neural activity as they view a piece of food, listen to conspecifics vocalizing at a food source, or both stimuli presented simultaneously. I find two regions, the nucleus taenia of the amygdala (TnA) and a medial portion of the caudal nidopallium, that show increased activity in response to the multimodal combination of stimuli but not in response to either stimulus when presented unimodally, and significantly increased activity in the lateral septum and medially within the nidopallium in response to both the audio-only and the combined audio/visual stimuli. Finally, I merge the previous studies’ methodologies and examine the individual factors and neurological activity as crows learn and master a task requiring the use of tools. I find that naïve crows predominantly use brain circuits associated with higher order thinking (the mesopallium, nidopallium, and nidopallium caudale) when first confronted with the task, yet their brain activity shifts to circuits associated with memory and motor control (hippocampus, tegmentum, nucleus basorostralis, and cerebellum) as they become proficient tool users. I additionally find that all crows that learned to use tools to solve the task were exclusively adults and predominantly females. This work showcases the capabilities, and limits, of the charismatic birds that live all around us.