BradleyL20

Impacts on Wildlife

Urban forests in the built environment affect urban wildlife in several ways. An urban habitat can impact wildlife behavior significantly and can alter the ecology of urban wildlife, influencing these organisms’ behavior. The interactions between humans and wildlife and the impacts of urbanization on these wildlife populations influence cities across the world.

Disturbances

Disturbances in urban forests are known for occurring more frequently and with higher intensities than in nature. Changes in the urban landscape can lead to greater competition for resources among species on fragmented areas of land, leading to more stress for urban wildlife^[1]. Urban wildlife is also exposed to warmer temperatures as well as higher levels of pollution as cities alter the natural environment significantly^[1].

The construction of urban infrastructure requires deforestation, leveling, and other activities that lead to habitat fragmentation, reduced genetic diversity, and changes in behavior^[2]. Urban wildlife is also exposed to higher amounts of toxic substances, including heavy metals, road treatments, or pesticides from lawns that can lead to abnormal reproduction or development^[1]. Consumption of prey species by domesticated pets, such as dogs and cats, also leads to an increased mortality rate in urban habitats^[2]. Urban forests are essential to creating habitats for wildlife within cities, and many species have adapted to living in the disturbed conditions of the built environment by utilizing urban green-spaces^[3]. Research has shown diverse green-spaces to be better suited for wildlife. For example, in Krakow, Poland, the species richness of owls was higher in parts of the city with varied land uses than more homogeneous areas^[4]. Additional support for land-use diversity in urban areas is provided in a study showing the importance of leaving dead and decaying trees on the landscape for wildlife habitat^[3].

Urban forests can alter natural diets by providing dietary supplements to wildlife in the form of fruit or nut-producing ornamental plants, trash, or even domestic pets like cats^[5]. By examining coyote scat and using stable isotope analysis, it was estimated that about 22% of the scat or 38% of the urban coyote diet was from human-created sources^[5]. Wildlife is also attracted to urban forests for their increased surface waters due to reduced runoff in these areas^[5]. Having wildlife interacting around humans in urban areas can create conflicts between humans and animals. A case study in Aspen, Colorado observed the foraging habits of bears, tracking their movements using GPS collars, and found that bears visited forested areas in the city with fruit-bearing trees for food^[6]. Alternatively, in a study on the behavioral ecology of urban deer populations, the authors discussed the difficulty of managing this species due to its positive public perception as an aesthetically pleasing animal^[7]. Proper species selection, placement of trees, and other urban forest management strategies can be utilized to mitigate human-wildlife conflicts in cities^[7].