Background and Rationale
Urbanization and biodiversity
In general, increasing urbanization results in a loss of biodiversity (Kondratyeva et al. 2020; Simkin et al. 2022). Urban development often creates isolated pockets of habitat, which are separated from each other by buildings and impervious surfaces (Figure 1). Increased noise levels, artificial light, anthropogenic food, and pollution further reduces the quality of remaining habitat and alters wildlife behaviour in human-modified landscapes (Isaksson 2018). Cities strive to retain biodiversity, as biodiversity supports many ecological processes such as seed dispersal, nutrient cycling, and pollination (Cox et al. 2017). Urban wildlife further supports human well-being and aids in mental health (Fuller et al. 2007). However, conflict with wildlife in the form of vehicle collisions, infrastructure damage, and disease spread is also common in urban centers (Schell et al. 2020). Retaining urban biodiversity while minimizing human-wildlife conflict requires the protection of the natural areas that accommodate the needs of rare, as well as abundant, species in urban landscapes.
Figure 1. Species can be characterized along an urban-rural gradient based on their tolerance of urbanized landscapes. Urban avoiders reach their highest densities in natural habitats and are most sensitive to human disturbance. Urban adapters are able to use human-modified landscapes to some degree but still have a reliance on natural landscapes features. Urban exploiters reach their highest densities in the most urbanized areas and thrive in highly modified environments. Image adapted from Schmidt et al. (2020).
Urban avoiders, adapters, and exploiters
Urban areas tend to support an increasing abundance of species that can adapt to or exploit urban landscapes, while other species decline (Figure 1; McKinney 2002; McIntyre 2014; Beninde, Veith, and Hochkirch 2015). Urban avoider species are species which reach their highest densities at the most natural sites (Fischer et al. 2015). Urban avoider species often have specific habitat requirements, such as large tracts of undisturbed forest or open grasslands, and are most sensitive to habitat disturbances that are associated with urbanization (Fischer et al. 2015). Examples of urban avoider species include many large mammals, such as wolves and ungulates. Urban adapters are commonly considered “edge” species in their natural habitats (McKinney 2002). These species take advantage of spaces where two distinct habitat types meet, or where environmental disruption has resulted in habitat alteration. Urban adapters still have a reliance on natural resources, but are also capable of utilizing resources generated by human activities. Rabbits, porcupines, and opossums are often considered to be urban adapters. Urban exploiters are species that have a high tolerance for urbanization and thrive in highly modified environments. These species are often generalists that can exploit a wide range of resources and are more tolerable of urban stressors, such as pollution, noise, and artificial light (Palacio 2020). Examples of species commonly thought to act as urban exploiters include raccoons, rats, and coyotes. The relative adaptability to urbanization is well known for some species groups, like rodents, but there is little information about the landscape features that drive species distributions in urban areas (McKinney 2002). Additionally, species’ responses to urbanization may be highly unique to individual cities (Fidino et al. 2020). Research conducted at the city-level can identify how species respond to local patterns of urban development.
The City of Edmonton
Edmonton's unique ecological network of large green spaces and natural corridors within a dense urban population makes it an ideal city for testing how species respond to landscape features associated with urbanization. The City of Edmonton has the largest urban park in Canada due to its bisection with the North Saskatchewan River (Figure 2), supporting an estimated 47 mammal species (City of Edmonton, 2008). This extensive river valley and ravine system preserves a high degree of natural area and connectivity for wildlife. However, urban sprawl and increasing population growth poses challenges for preserving remaining suitable habitat and species diversity (City of Edmonton, 2008). Understanding how mammal species select landscape features can help predict how species communities may shift in response to further urbanization as well as inform human-wildlife conflict management. In the City of Edmonton, understanding landscape-scale attractants is especially relevant for coyotes, who are commonly thought to act as urban exploiters and have a particularly high density in Edmonton’s urban core, where there is an increased risk of human-wildlife conflict (Raymond and St. Clair 2023). Determining how urban-exploitative coyotes actually are requires investigation into how coyotes and their prey species select landscape features in urban environments.
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Figure 2. The City of Edmonton's river valley and ravine system.
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Research Objectives
The purpose of this study is to delineate patterns of mammal species assemblages across an urbanization gradient in Edmonton, Alberta to determine the relative tolerance of species to urbanization.
My specific research questions are as follows:
1) Which mammal species have similar responses to urbanization in Edmonton?
2) How do the mammal species in Edmonton fit within an urban avoider, urban exploiter, and urban adapter framework?
3) Do coyotes act as urban exploiters in Edmonton?
My specific research questions are as follows:
1) Which mammal species have similar responses to urbanization in Edmonton?
2) How do the mammal species in Edmonton fit within an urban avoider, urban exploiter, and urban adapter framework?
3) Do coyotes act as urban exploiters in Edmonton?