It is well known that humans are able to represent the mental states of others. This ability is commonly thought to be unique to humans. However, recent studies on the food caching, gift giving, and cooperative behaviours of Corvids and Parrots provide evidence for this ability in birds. Upon examining the empirical evidence, I argue that the best explanation for these behaviours is that birds are able to represent conspecifics as having particular mental states. I further argue that birds are able to do this by simulating the minds of conspecifics.

It is well known that humans are able to represent the mental states of others. This ability is commonly thought to be unique to humans. However, recent studies on the food caching, gift giving, and cooperative behaviours of Corvids and Parrots provide evidence for this ability in birds. Upon examining the empirical evidence, I argue that the best explanation for these behaviours is that birds are able to represent conspecifics as having particular mental states. I further argue that birds are able to do this by simulating the minds of conspecifics.

Rule governance is critical to human society. However, could rule governance be found in non-human animals? A six year old, female, African white-necked raven (Covrus albicollis) named Shade correctly followed informal verbal commands to retrieve specified objects in the past. This ability was tested using two different methods. Both methods involved the researcher verbally asking the bird to retrieve one object out of two either from the same room or an adjacent room. While initial results were not significantly different than chance, review of trial recordings revealed that it is possible to predict when the bird will retrieve an incorrect object based solely on specific behaviors, termed inattentive or uninterested. Trials marked as inattentive by observers were significantly more likely to be incorrect than correct. This indicates that the bird was capable of retrieving the correct object, but that she also occasionally, intentionally retrieved the incorrect object.

This dissertation explored the social cognitive abilities of the Clark’s nutcracker (Nucifraga columbiana), a relatively non-social, food-caching corvid. Corvids are a family of large-brained birds, which are capable of remarkable cognitive feats (e.g., future planning, tool use). These cognitive abilities have been revealed predominantly by testing social species, supporting popular theories that living in social groups drove the evolution of complex cognition. However, few studies have investigated the social cognitive abilities of corvid species that do not live in large groups. Here, I developed novel procedures using the food-caching behaviour of Clark’s nutcrackers as a tool to explore two cognitive abilities predicted to be limited to social species: mirror self-recognition (Chapter 2) and cooperation (Chapter 4). In Chapter 2, birds cached food when alone, with a conspecific present, and with a regular or blurry mirror. The nutcrackers suppressed caching with a regular mirror (as done with a conspecific), but not with the blurry mirror. When integrated with the traditional ‘mark test’, the birds also showed evidence of self-recognition with the blurry mirror by attempting to remove a coloured mark placed on their body with the blurry mirror, but not with an opaque barrier. In Chapter 3, I discuss the importance of self-recognition as a precursor for complex and flexible social cognitive abilities such as cooperation. To investigate cooperation, in Chapter 4 the birds experienced having their caches exchanged with another bird over multiple trials. This procedure assessed whether the normal response of cache suppression with a conspecific could be over-ridden if the experimental contingencies made cache sharing beneficial. The nutcrackers continued to cache in this context, and male birds increased caching when cooperation from the conspecific was exaggerated artificially by the experimenter. Combined, the results indicate the non- social Clark’s nutcracker is capable of mirror self-recognition, and the ability to distinguish one’s ‘self’ from others may facilitate flexible caching decisions, contrary to the predictions of the social living hypotheses. The findings indicate social living alone does not strongly predict complex cognitive abilities and, instead, that multiple evolutionary paths exist for the development of complex cognition. / October 2016

Although early reproduction within a breeding season often leads to higher reproductive success in seasonal environments, it is still not well understood how reproductive success can be influenced by climate both indirectly through the timing of breeding or by directly altering parental behaviour. In this thesis, I investigate the role of ambient temperature in reproductive success through its effects on the timing of reproduction and brooding in a population of gray jays, Perisoreus canadensis. In chapter 2, I test whether (i) female gray jays adjust laying date in response to temperature, (ii) individual or environmental characteristics constrain this plasticity, and (iii) laying date influences reproductive success. Females laid earlier in warmer years than in colder years; females partnered with older males laid earlier than females partnered with younger males at colder temperatures, but not at warmer temperatures. Early layers were more likely to rear at least one nestling and have a dominant juvenile survive the summer. These findings suggest that male experience could advance female laying date at cold temperatures and subsequently increase the probability of a positive nesting outcome. Though cold temperatures appear to limit timing of reproduction in gray jays, previous work in this system suggests that cold temperatures could better preserve perishable winter food stores. Thus, in chapter 3, I test whether temperatures during early offspring development interact with timing of reproduction to influence reproductive performance. Colder ambient temperatures during incubation were associated with larger brood sizes than warmer temperatures among late breeders, but temperature did not influence brood size among early layers, indicating that costs of late breeding may be amplified by temperatures that are unfavourable for food storage. This thesis contributes to our understanding of the environmental factors that determine reproductive performance, both through effects on timing of reproduction and after eggs are laid.

Social intelligence is thought to have evolved as an adaptation to the complex situations group-living animals encounter in their daily lives. High levels of sociality provide individuals with opportunities to learn from one another. Social learning provides individuals with a relatively cheap and quick alternative to individual learning. This thesis investigated social learning in three corvid species: gregarious rooks (Corvus frugilegus) and jackdaws (Corvus monedula) and nongregarious, territorial Eurasian jays (Garrulus glandarius). In addition to that, the species' social structure was analysed and individual differences between members of each species were determined. Introducing the field of social learning research, I presented a new framework for investigating social learning, combining ecology, ethology and evolution. Experiments were conducted within that framework. I found that rooks and jackdaws develop social bonds and dominance hierarchies, whereas Eurasian jays do not. This is most likely related to their territoriality. In two experiments using two-action tasks, jackdaws learned socially. The underlying social learning mechanism was enhancement, which fits in with their feeding ecology. Rooks did not show social learning when presented with videos of conspecifics opening an apparatus. This might have been due to the difficulty of transferring information from videos or due to an ingrained 'affinity' to innovation and/or rapid trial-and-error learning overriding social learning processes. Individual differences along the bold/shy axis existed in all three species, but they were not stable across contexts. Thus, it seemed that the individuals perceived the two seemingly similar contexts that were designed to investigate neophobia and exploration (novel object in familiar environment; novel environment) as two different situations. The information may therefore have been processed by two distinct underlying mechanisms, which elicited different responses in each of the contexts. The implications of the findings of this thesis are discussed with regard to the new framework, integrating sociality, social learning and individual differences with the species' ecology.