It's a struggle many communities across the country have encountered: A Starbucks moves in and a year or two later the local coffeeshop closes down. Or a local bookseller loses business to a Barnes and Noble and eventually disappears.
Researchers are now realizing the same thing may be happening among wildlife.
Native varieties of wildlife have been facing off with their own version of national chains -- the so-called "exotic" species that often spread quickly in new areas -- pushing them out or reducing their numbers.
The result, scientists say, is just as city blocks across the United States are starting to look more and more the same, so are wildlife populations. In place of big businesses like T.G.I. Friday's, McDonald's and Dunkin' Donuts, the "chain" species among wildlife are creatures like the European starling, goldfish and pigeons. Researchers call the effect "biotic homogenization."
Same Fish, Different Rivers
"We're only starting to get a handle on how much and what ways animal communities are being homogenized," said Julian Olden of the University of Wisconsin in Madison. "Our evidence now is strongest for fish, birds and plants."
One glaring example, Olden says, is the Colorado River Basin in the American Southwest. Its waters were once teaming with native pupfish, Colorado pipe minnows and native sucker species. Now, as Olden says, "It's a real hodgepodge."
Over half the fish in the rivers are exotic breeds introduced over the years either by people dumping their unwanted aquarium pets or by state agency officials stocking the waters with species like European brown trout to promote sport fishing. As this happens in more and more rivers, the fish populations are starting to grow more similar.
"On average, pairs of states have 15.4 more species in common now than before European settlement of North America," said the University of Wyoming's Frank Rahel, in a study published in the journal Science.
Scientists have shown a similar phenomenon is happening among birds. As human development converts more and more countryside to pavement-covered landscapes, certain varieties of exotic birds have been finding their niche in urban environments.
Just about every city in the United States, even the world, hosts high numbers of pigeons, starlings and sparrows -- as Olden says, "the kinds of birds that you almost step on." These aggressive, exotic birds have learned to use such urban jungles to their advantage. Meanwhile, native species, like the bluebird, are being pushed out.
"It is not serendipitous circumstance that house sparrows can be found begging for French fries outside McDonald's restaurants anywhere in the world," ecologist Robert Blair of the University of Minnesota warns in a June edition of the journal Ecology and Society.
Having Our Land and Sharing It Too
But Michael L. Rosenzweig of the University of Arizona says the picture isn't all doom and gloom. In his book, "Win-Win Ecology: How the Earth's Species Can Survive In The Midst of Human Enterprise," Rosenzweig points out there are ways to develop land so it accommodates both wildlife and people -- even business.
"We can have our land and share it, too," he writes. "I call this 'reconciliation ecology.' Reconciliation ecology means remodeling our habitats so that they continue to serve us but also support wild species."
The surprise success of red-tailed hawks, like the famous Pale Male in New York City's Central Park, is an example of how a city park can push the odds in favor of rare animal species, even in the most urban of urban environments.
Similarly, the lesser kestrel is on the brink of extinction worldwide. But in the city of Jerusalem, the bird has discovered the city's roof tiles are perfect for nest-making and is thriving there. Just south of Miami, meanwhile, the Turkey Point power plant has 80 miles of cooling tubes that turn out to be perfect habitat for crocodiles.
By recognizing what man-made features can be helpful to native and threatened wildlife, Rosenzweig argues people can cater their development to make both humans and native animals comfortable.
If we don't start approaching development this way, Olden says, wildlife could become as homogenous as many of our cities. That could discourage interest in wildlife and, consequently, their preservation. As he points out, if every place is the same, why go anywhere?
"When you have big box retailers coming in and replacing mom and pop shops -- people can understand that, because they see it," he said. "Now I think people also have to grasp this is happening biologically."