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Urbanization is viewed as a major threat to global biodiversity because of its role in the loss and fragmentation of low-lying, productive habitats associated with coastal plains and river valleys. My study examines the effects of urbanization on the movements and distribution of songbirds in Calgary, Alberta, Canada. I conducted playback and translocation experiments to assess the permeability of small-scale (e.g. transportation corridors, rivers) and large-scale (e.g. multi-lane expressways, areas of urban development) features of the urban landscape, respectively. I then used these empirical data to parameterize spatially explicit models and determine functional landscape connectivity across the study area. Finally, using point surveys conducted at 183 sites across the urban matrix, I examined the role of land cover type, local vegetation characteristics, landscape-level forest cover, and isolation from natural features on the distribution of songbirds. In 563 playback trials involving the responses of 2241 birds, I found that the size of the gap in vegetation was the most important determinant of movement across linear features; the likelihood of movement sharply decreasing as the gap in vegetation exceeded 30 m. The results of 176 translocation trials provided further evidence of the barrier effect of gaps. Multiple gaps, in particular, constrained the movements of both yellow warblers (Dendroica petechia) and black-capped chickadees (Poecile atricapillus). The bird surveys revealed that natural forest stands played a critical role in sustaining regional avian diversity in the study area. Moreover, functional distance to the nearest forested natural area or water body often explained more variation in the probability of occurrence of focal species than straight-line distance, suggesting that barriers identified from the permeability experiments may have affected not only the movements of songbirds but their settlement patterns as well. Taken together, my results suggest that preserving a functionally connected network of natural areas is vital to conserving avian biodiversity in cities. My research describes novel methodologies for characterizing the composition and configuration of highly heterogeneous and fragmented landscapes. It also provides a unique examination of the link between the movement behaviour of individual birds and population-level distribution patterns within this context. / Ecology

Animals exhibit a wide variety of social behaviours that are shaped by the external group social structure. Thus, understanding social behaviours and processes requires examining the individual social associations that form the basis of a group’s social network. The first objective of this thesis was to assess the consistency of social position within wild networks of black-capped chickadees (Poecile atricapillus) and to evaluate the effects of individual behavioural traits (exploratory personality and social dominance) on network position. Intra-annual social position was found to be repeatable and centrality increased with dominance rank, suggesting that dominant individuals occupy more central positions. The second objective of this thesis was to evaluate how network position and individual traits influence the transmission of social information through groups; the use of information acquired by other group members is expected to be an important benefit to group living. Social information regarding the location of novel foraging patches was observed to be transmitted through all eight chickadee groups. The rate of information transmission was found to be positively associated with dominance rank, but was not influenced by exploratory personality, indicating that dominant individuals may have greater access to social information than more subordinate individuals. The final aim of this thesis was to assess if social information transmission varied between urban and rural environments, as increased resource variability in more rural sites was expected to lead to higher reliance on social foraging cues. However, no effect of level of urbanisation was detected on the transmission of social information regarding novel food sources, which may indicate a habitat-independent strategy of social information use in chickadees. In general the results from this thesis indicate the importance of dominance status on individuals’ position within a social group, which can lead to differential exposure to social processes, such as social information transmission.

Food-caching birds like black-capped chickadees offer unique advantages for studying neural processes underlying episodic memory. Chickadees exhibit prodigious memories—they can cache thousands of food items throughout their environment and use memory to navigate back to these hidden food stores. Additionally, their hippocampal circuit is simplified relative to that of mammals, containing far fewer inputs and outputs. However, little work had been done to understand the neural processes underlying these animal’s memory abilities. This thesis details several projects that aimed to better establish food-caching birds as an animal model of memory for systems neuroscience. In Chapter 2, we described the creation of behavioral tasks to utilize the chickadees’ natural memory behavior. Here, we monitored chickadees’ behavior while they cached food into a grid of sites covered by rubber flaps. We then applied probabilistic modeling to examine how different strategies guided birds’ choices during caching and retrieval. Chickadees used memories of the contents of individual cache sites in a context-dependent manner, avoiding sites that contained food during caching and returning to those same sites during retrieval. These results demonstrate memory flexibility in an animal in a tractable spatial paradigm. In Chapter 3, we asked whether the bird brain had a region that was similar to the entorhinal cortex. We found that the dorsal lateral hippocampal formation (DL/CDL), one of the main inputs to the chickadee hippocampus, sharded marked anatomical and physiological similarities to the mammalian entorhinal cortex. We first used retrograde and anterograde tracing to examine the connectivity between DL/CDL and the hippocampus, as well as DL and the rest of the pallium. We found that the topographic patterns of DL/CDL input were similar to those of the mammalian entorhinal cortex. We next examined the physiology of DL, using 1-photon calcium imaging to monitor neural activity while birds performed a random foraging task. Like the entorhinal cortex, DL contained multi-field ‘grid-like’ spatial neurons, as well as border cells, head direction cells and speed-tuned cells. Collectively, these results establish DL/CDL as an entorhinal cortex analog. In Chapter 4, we expanded the anatomical analysis to examine all of the inputs to the hippocampal formation. We varied our injections of retrograde tracers along the hippocampal long and transverse axes to examine if, like in mammals, there were topographic input patterns along these major axes. We found many patterns in input that were highly reminiscent of mammalian connectivity: like in rodents, visual pallial input preferentially innervated the septal portion of the hippocampus, while amygdala input preferentially targeted the temporal portion. These results further solidify the homology between the mammalian and avian hippocampal formations. Collectively, through these sets of experiments, we have laid the groundwork for studying the black-capped chickadee in a modern neuroscience context.

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