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Urbanization and biodiversity

The transformation of King County's landscape resulting from development, agriculture, and forestry has affected all native wildlife species in King County in some way. Vertebrate and invertebrate wildlife species have experienced habitat alteration, interrupted migration patterns, displacement, reduced reproductive success, and exposure to invasive species.

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Urbanization threatens biodiversity

Through pollution, fragmenting of habitat, and the introduction of threats like automobiles and pet cats, urbanization can have drastic effects on a region's biodiversity.

Overview: how urbanization affects biodiversity

If you could step back in time about 175 years, almost all of the developed areas in King County would have been covered with forest or wetland or grassy meadows. Much of downtown Seattle was a big estuary. The landscape of this area prior to European colonization would have been rich in wildlife habitat.

Fragmented habitat

Wildlife habitat today is highly fragmented by roads and other human infrastructure. When forest patches become too fragmented, many of the animals that use this habitat become more susceptible to predators, including nest predators, and parasites. Non-native invasive animal species continue to be a growing threat in King County, as more are introduced over time.

Pollution

Development also brings pollution, which is another threat to biodiversity. Fishes and marine mammals seem to be particularly susceptible to pollution. Toxic contaminants include chemicals used for industrial, consumer, and agricultural purposes, transportation-related chemicals, and byproducts from manufacturing and combustion of fossil fuels.

Harbor seals and killer whales carry large concentrations of polychlorinated biphenyl (PCBs) compounds and increasingly greater concentrations of flame retardant chemicals in their fatty tissue. The effects of these chemical loads are not well known, but in the case of killer whales, the contaminants can weaken immune systems, cause reproductive failure, and lower the survival rate of calves through maternal transfer of contaminants.

Shoreline armoring

Shoreline armoring is another aspect of development that leads to a loss of marine habitat. It also interferes with sediment transport. Throughout Puget Sound, armoring has led to a decline in forage fish spawning habitat, feeding habitat for marine birds, and total area and abundance of marine plants.

Species you may encounter—and not necessarily want to

Urbanization can lead to an increase in the number of human-wildlife interactions. It's not unusual to encounter wildlife in urban and urbanizing areas. For example, black bears frequently show up at trash cans in semi-rural areas to see what food scraps are there.

You may encounter wildlife in your yard or neighborhood that you were not necessarily expecting or don't know how to handle. WDFW's Living with Wildlife web site offers information on just about any species you might see in your yard or other spaces frequented by humans.

Coyotes

Coyotes can be found in urban, suburban, and rural areas. Coyote activity is regularly reported in neighborhoods across the city of Seattle:

The Washington Department of Fish and Wildlife provides a dedicated coyote page on their Living with Wildlife site to address frequently asked coyote questions.

A coyote sitting in the corner of a room by a bookcase. View of the coyote is partly obscured by a large houseplant and a brightly colored fabric decoration.
Coyotes can turn up anywhere!  This one wandered into an open back door of a house north of Novelty Hill Road.

Beavers

Beavers are incredibly industrious creatures that live in streams and wetlands even in our urban areas. They are a natural part of these aquatic ecosystems, and in fact they create much-needed ecosystems. They are often perceived as a problem because of their ability to back up water in places it is not always welcome. However, more often than not, beaver dams do not cause problems and instead provide a large suite of benefits.

Learn more about beavers on our Beavers in King County page.

Wildlife and pet cats

One of the biggest threats to birds in our urban and urbanizing areas is our pet cats. Most cat owners have no idea how much damage their pets do to wildlife. According to the American Bird Conservancy, "In the United States alone, outdoor cats kill approximately 2.4 billion birds every year. Although this number may seem unbelievable, it represents the combined impact of tens of millions of outdoor cats."

The American Bird Conservancy launched their Cats Indoors campaign in 1997, and their website includes valuable information for cat owners and wildlife conservationists. All cat owners should educate themselves about the impacts their pet may be having on the native biodiversity outside their doors.

Your yard may provide valuable wildlife habitat

Believe it or not, animals use your yard. You can make the most of your little patch of potential habitat by learning about gardening for wildlife and possibly even getting your yard certified as wildlife habitat.

  • The Washington Department of Fish and Wildlife's Habitat at Home page will helps you understand and appreciate the wildlife around your home. You can make your property a better place for songbirds and other wildlife species that have lived in your area since long before people began to settle.
  • You can certify your backyard via National Wildlife Federation's Certified Wildlife Habitat™ program.
  • National Wildlife Federation's great web site on Gardening for Wildlife - NWF's Certified Wildlife Habitat™ program shows people the benefits of gardening for wildlife. From backyards and apartment balconies to schools, businesses and farms, no garden is too big or small to turn into a wildlife-friendly habitat.

 

Wildlife and roads

Road Ecology is a growing field. To reduce vehicle-wildlife collisions, many transportation agencies are now taking wildlife crossings into consideration during their planning. Some places with successful wildlife crossing projects include British Columbia, Montana, California, Florida, New England, all over Europe—and Washington State.

The Washington State Department of Transportation has undertaken a number of wildlife habitat connectivity projects, including the Snoqualmie Pass East overcrossing. Here in King County, you can find a wildlife crossing over Redmond's busy Novelty Hill Road. It was built in 2013/2014 and has seen regular use ever since it was completed.

Black-and-white trailcam photo of a coyote, facing the camera, in tall grass and shrubs on a wildlife overpass.
Black-and-white trailcam photo of a buck deer, angled away from the camera, in tall grass on a wildlife overpass.

Defenders of Wildlife's Habitat and Highways campaign has two objectives that sum up the best approach to roads and wildlife:

  • Reduce the impact of roads and highways on wildlife and habitat. Modify existing roads where necessary to allow wildlife to cross, and minimize impact on the surrounding environment.
  • Reduce future impacts by incorporating wildlife conservation into transportation planning. Avoid wildlife habitats and environmentally sensitive places with future road development.

See more of Defenders of Wildlife's Road Ecology work in their publication Getting up to Speed: A Conservationist’s Guide To Wildlife and Highways.

Related Topics

Biodiversity

Biological diversity, or biodiversity, is life in all its forms.

Climate change

In the face of climate change, biodiversity conservation may be of critical importance.

Invasive species

Non-native plants and animals can threaten King County's biodiversity.

Biodiversity regulations

State, local, and federal regulations protecting biodiversity in King County.
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