SciTech

Wild in the streets: Are animals invading urban areas?

Urban deer: Such phenomena have “more to do with human activity than changes in animal behavior,” according to Nils Peterson of N.C. State. His area of expertise: intersections between human and natural systems.
Urban deer: Such phenomena have “more to do with human activity than changes in animal behavior,” according to Nils Peterson of N.C. State. His area of expertise: intersections between human and natural systems. mschultz@newsobserver.com

A half-dozen deer in the back yard, a pair of foxes on the cul-de-sac, a black bear beside the strip mall’s Dumpster. Sometimes it seems that wild animals are everywhere, including urban and suburban neighborhoods.

Nils Peterson, who teaches a course at N.C. State called Human Dimensions of Wildlife Management, says increased sighting of forest animals in urban places may seem surprising, but there are good reasons for it – at least from the animals’ point of view.

“North Carolina is among the states with the highest levels of urban sprawl,” he said. “The area we occupy has grown so rapidly in a low-density way, that there’s a lot of overlap with wildlife – a lot more so than in the past. But the phenomenon has more to do with human activity than changes in animal behavior.”

Building a house on an empty lot doesn’t just disturb animals living on that quarter acre; it also starts a chain reaction of development, causing another 2.5-acre loss due to road construction, addition of schools, shops and other businesses, he added.

“Some species do great under those conditions, but some do poorly,” Peterson said.

Those that do best are typically generalists, such as coyotes, wolves, raccoons, house sparrows and cardinals. They are capable of changing their habits when development alters their previous lifestyle.

Tristan Donovan, author of “Feral Cities: Adventures with Animals in the Urban Jungle,” concludes that sneaky, adaptable, fast breeders do best in cities – especially animals that that aren’t too picky about what they eat. Donovan says coyotes even live longer in cities than in rural areas, probably due to fewer predators.

Somewhat less adaptable are “transition” animals such as bobcats, Peterson said.

“They in some ways are more of a specialist because they only eat living prey,” he explained. “They won’t eat out of trash cans like coyotes, but they can eat lots of different kinds of animals and can hide under porches.”

Then there are the specialists – birds that can nest in only one type of tree cavity, for example, or have a very limited diet.

Salamanders are known to not do well in urban areas. They need both a grassy habitat and a pond for breeding – and the pond must be without fish, because fish will eat all their eggs. Salamanders also absorb many pollutants through their skin, Peterson added.

Preserving land through parks and other natural spaces is a useful way to help support urban and suburban wildlife, many of whom take advantage of this “edge habitat” to live and breed. Deer are a great example.

Sharing space

But other species need more protection. They require a buffer of green space, and avoid the edges of urban environments.

“Many kinds of birds are interior species; they need large pieces of unbroken habitat,” Peterson said.

Greenways are great, but a wide path down the middle breaks up the tree canopy, which is an important factor for some types of birds and other animals, he said. Ambient noise in cities is another issue. Birds that vocalize for breeding, to establish territory or for other purposes have been known to change their song, raising it to a higher pitch that is easier to hear than the low rumbling of urban ambient noise.

In a few cases, sharing space with wildlife causes severe consequences. A string of shark bites along the Carolinas’ coast this summer is one example.

“Sharks are just doing what they do, but when you have 50,000 people in the water, it’s more likely to happen,” Peterson said.

As people and animals live more closely together, animals aren’t the only ones who are having to adapt. Keeping small dogs in sight when there’s a coyote in the area or dispatching cleaning crews to mop up after flocks of urban geese are some examples.

Peterson also has noted some adaptive behavior by human residents of new subdivisions.

“At first, they become upset when deer eat their ornamental plants. But 20 years down the road, they either have fences or plants that deer won’t eat.”

Finding better ways to protect animal habitat and include more swaths of nature in our environment won’t just be good for wildlife. Studies have shown that it improves the quality of life for humans, too, Peterson said.

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