The number of species varies greatly among taxa. In birds, for example, the parvorder Passerida contains 3556 species while the Odontophorida (New World Quails) contains only six species. This uneven distribution of species among avian taxa is not random and therefore warrants an explanation. The behavioral drive hypothesis stipulates that the capacity for innovation, coupled with the rapid transmission of the behavioral novelty to conspecifics, may expose individuals to new selective pressures and help fix mutations that would otherwise not be expressed. This should lead to accelerated rates of evolution. I test this hypothesis by examining the link between behavioral flexibility and the number of species per taxon. I adopt a comparative approach and seek a general explanation of richness, thereby removing the traditional focus placed on the success of the songbirds and on their complex singing apparatus. I use two measures of flexibility, feeding innovation rate and relative brain size. (Abstract shortened by UMI.)

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Over fifty percent of humans live in cities. The environmental cost of this is massive, as is the potential for utilizing privately held yards as an integral part of conservation in urban areas. The Backyard Habitat Certification Program (BHCP) in Portland, Oregon, was established to reduce invasive plants, support wildlife, and promote conservation. The program involves > 3000 yards certified at three tiers. While onsite inspections are required to verify compliance, there has never been an assessment of the value of these yards to wildlife. Chapter 1 examined the relationships between the urban landscape and bird distributions outside of yards. Chapter 2 evaluated the ability of the program to separate yards by assessing differences in vegetation structure and composition. Chapter 3 tested if avian abundance, richness and diversity in yards are a product of responses to yard or landscape vegetation structure. Avian data was collected at 146 yards and 73 random locations in 2013 and 2014. Public landscape data was used to collect yard data in the field. Avian abundance, richness, and diversity were affected negatively by urbanization (especially impervious surface) and population density, but positively by tree cover. The BHCP was effective at distinguishing platinum yards from others, but overlap was relatively high among gold, silver and uncertified yards. Avian abundance, richness and diversity within yards was less affected by yard vegetation than the structure of habitat in the surrounding landscape. Species responded individualistically to yard vegetation and the urban landscape, and response was a continuum of tolerance to urbanization. Ultimately, the ability of yards to support wildlife will depend on wide scale neighborhood participation.

Urbanization is known to have a negative impact on biodiversity. However, it is possible to increase bird species richness in cities through local actions such as increasing vegetation density and diversity. My first objective was to compare bird density and diversity on the island of Montreal among four urban habitat types: low-density and medium-density residential sectors, and residential and natural parks. A second objective was to determine the presence of bird species assemblages within these four urban habitats and a third was to explore associative relationships among six mainly shrub-nesting bird species and the vegetation they use. Point counts were conducted in each of 103 locations. Environmental variables measured consisted of the type (coniferous versus deciduous), density and height of vegetation within each 1 ha sector. Results revealed a decrease in bird abundance from medium-density residential habitats, residential park, low density residential habitats to natural parks and an increase in diversity from medium density residential habitats, low density residential habitats, residential parks to natural parks. Bird assemblages were determined through correspondence analysis. Most bird species were associated with at least one type of urban habitat. Associations between bird species and vegetation were measured through canonical correspondence analysis. The six focal species associated with shrubs demonstrated different levels of association with different habitat variables.

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