Wildlife Types Vary According to Urban Density

Cities tend to have similar wildlife types and habitats, no matter where you may live in the world. That’s why Norway rats, cockroaches, and pigeons are everywhere—they follow in our footsteps. But research has shown that native plants and wildlife are plentiful at the city edges but decrease as they get closer to downtown. Michael McKinney from the University of Tennessee sums this up nicely in his 2006 article in the journal of Biological Conservation. Entitled Urbanization as a major cause of biotic homogenization, McKinney collects a wealth of data from around the world, as well as mining existing data sets, on how wildlife and plants respond to urban density. He observes that cities tend to share similar wildlife types and habitat structures and thus are very homogenized (similar) and homeostatic (unchanging). Whereas city edges that abut natural conditions tend to be more varied and dynamic thus providing more habitat types and food for urbanophobes (wildlife that do not like being around humans and their environments). Based on the information and references McKinney provides in his article, I observed that there are three primary and distinct urban habitat zones—periurban, suburban, and urban. Or, in other words, the farther that one gets from the wildland interface and the denser the development, that wildlife and habitats change. This may be useful information to landscape architects or planners that seek to provide green spaces for wildlife habitat in densely urban areas.  The types of wildlife that you hope to attract probably depends upon the scale of habitat that you are designing and how they will arrive from native populations. The following graphic that I developed summarizes the general wildlife and habitat characteristics as provided by McKinney (2006):

It’s been noted that urban areas may exhibit a high diversity of plants and animals, sometimes more than the adjoining countryside. But while the numbers may be high due to more planted exotic vegetation species; the quality of the habitats, food, and ecosystem services may actually be more impoverished as compared to a native landscape. This is mostly due to the use of plants (native or exotic) with a reduced gene pool and a lack of resilience. McKinney notes that using local native plant species in urban areas enriches not only the urban genepool, but creates a much richer environment for people.