May 15th, 2012 by

Every year from mid-March to early November, up to 1.5 million Mexican free-tailed bats hang out and make roost under the Congress Avenue Bridge in downtown Austin, Texas. As the largest urban bat colony in North America, these bats have created a very unique tourist attraction in the city, as more than 100,000 visitors come each year to check them out, generating millions of dollars in tourism revenue annually. Not to mention that these bats will eat 10,000 to 20,000 pounds of insects each night during their flights around the city. Thank goodness for bats!

As many of us have likely witnessed, urban environments can offer an array of habitats for exciting wildlife. Growing up, my family saw gorgeous red-tailed hawks looming around our neighborhood, red foxes that would scurry across the streets and coyotes that would sometimes briefly appear in backyards. Living in the D.C. area now, I appreciate that I can visit one of our local urban parks and see a slightly different variety of wildlife.

Urban forests provide critical habitat to wildlife in cities, especially those reliant on corridors for their species’ survival. Corridors are areas that wildlife, such as migratory birds and mammals, use to move from one location to another. They can come in the form of natural urban rivers or streams or in the form of man-made right-of-ways and greenways that connect nature preserves and parks. And, as a 2010 study shows, even small patches of urban forests are often key for migrating birds, such as the Swainson’s thrush, a species that is declining throughout much of its range.

Black-crowned night heron

Black-crowned night heron. Credit: Rennett Stowe/Flickr

Other studies further confirm urban forests as crucial habitat for birds. For example, Baltimore, Maryland, houses a least a third of the bird species that inhabit the entire region, including black-crowned night herons, indigo buntings, scarlet tanagers, white breasted nuthatches and a variety of warblers. In urban areas in Minnesota, approximately 35 bird species nest in or are permanent residents of urban forests, three of which are species of state conservation concern: the northern flicker, chimney swift and brown thrasher.

Just as we manage for our urban forests, we must also manage for the wildlife in those forests. And, different wildlife species require different types of habitats. That is why it is important for urban forests to contain multiple layers of vegetation, including ground cover, understory and canopy, and a variety of tree species. Some species can be selected to encourage specific types of wildlife, such as species with different flowering and fruiting seasons.

Although wildlife can create unique challenges in urban environment (stay tuned for a future blog post), the value of urban wildlife cannot be understated. Not only does urban wildlife provide enjoyment for people and direct economic benefits to cities (think of the bat tourism in Austin), but according to the National Wildlife Federation article “Wild Life in the Concrete Jungle,” national polls have shown that 40 percent of U.S. households do something to attract wildlife to their homes, from installing birdfeeders or ponds to planting certain shrubs and flowers. And, according to the same article, William Shaw, chair of the wildlife fisheries science department at the University of Arizona, says that “promoting urban wildlife is not purely a matter of providing entertainment for people. It is a crucial component for maintaining biodiversity.” Whether we are talking about birds, coyotes, squirrels, insects or bats, urban wildlife is key in helping to maintain stable healthy ecosystems.