Foxes take in rounds of golf on Hains Point. They stalk rats near the Lincoln Memorial. And just about everywhere in the Washington area, they slip gracefully through back yards, giving people the chance to spot the small, sly canines from their living room windows.

Wildlife experts have grown accustomed to the fox as a relatively benign mainstay of urban and suburban life. So it came as a surprise to many when investigators concluded that it was probably a red fox, and not a bobcat as was initially thought, that felled a bald eagle at the National Zoo in early July.

The fox, they say, should have known better than to attack a full-grown bald eagle, with its razor-like talons.

Yet when Robert Colona, a fox expert for the Maryland Department of Natural Resources, investigated the scene for the zoo, he spotted all the telltale signs: fox prints, fox fur and bite marks on the bird.

"Foxes are opportunistic predators," Colona said. And for whatever reason, this particular fox decided that in the eagle's cage that night, opportunity awaited.

Wildlife biologists have speculated that the fox was going after some half-eaten fish on the ground of the cage, not realizing it was taken.

Others have wondered whether, in the midst of that night's violent thunderstorm, the eagle became disoriented or injured. In any case, the fox left the eagle mortally wounded but didn't stick around to eat it, indicating the eagle had fought back.

"I would guess [the fox] was probably trying to get a free meal," said Randy Farrar, Colona's counterpart in Virginia, "and it ended up getting more than it bargained for."

Foxes, which typically weigh no more than 15 pounds but possess large mouths and sharp teeth, have a well-earned reputation as fierce predators. But they're also not above the free meal, which is why Washington and its suburbs have become such popular stomping grounds for the canines. Although scientists keep no statistics on local fox populations, wildlife experts say the number of urban and suburban foxes has risen in the past few decades.

In part, that's because development continues to encroach on the animals' natural homes in the country. But it's also because foxes have adapted well to city living. With bountiful trash bins and the promise of cat food left out on back porches, the Washington area has become a draw for country foxes. They have even established dens in the heart of the city, with one family making its home near the Lincoln Memorial, another at Hains Point and numerous others in Rock Creek Park and in smaller parks across the region.

Earl Hodnett, Fairfax County's wildlife biologist, said that growing up in the county, he never saw foxes. Now he gets residents reporting sightings to him every day. What's changed is that rather than fleeing at the first whiff of a human, foxes have learned how to exploit people, while keeping their distance.

The foxes build dens under porches. They hunt in back alleys, sometimes in the middle of the day. They scarf up the rodents that come with the trash. In keeping with their reputation for craftiness, foxes study human behavior and react accordingly.

"They'll map out a neighborhood so that they know when a dog is going to be in the back yard, which day is garbage day and who has a bird feeder," Hodnett said. "It's a good example of evolution, but it's accelerated. We tend to think of animals adapting over time, with time being thousands or millions of years. But here we've got an animal doing a 180-degree turn in a matter of decades."

Gopaul Noojibail, who manages natural resources along the Mall and in surrounding areas, said three thriving fox families live under his watch. "The foxes we have are robust," he said. "They're large and healthy."

They're also an asset for people.

"They provide an environmentally beneficial and free form of rodent control," Noojibail said.

Notwithstanding the fatal attack on the bald eagle, wildlife experts say foxes prefer to go after the safe kill -- such as a rodent -- rather than risk injury by attacking something bigger or more powerful than they are. Although foxes have been known to go after animals as large as sheep, humans are generally safe, provided the fox isn't diseased and doesn't feel threatened. "The fox has a reputation that exceeds its size," said Bob Ford, natural resources manager for Rock Creek Park. "When you see them, you say, 'My gosh! What a tiny critter.' Generally, they're going to run from you."

It's not unusual anymore for a fox to stop and watch a human. But it is unusual if a fox approaches, and it might mean the animal is rabid. Every year, a handful of rabid foxes are found in the region.

Also, although it happens relatively rarely, foxes are capable of preying on pets, such as kittens or small cats and dogs, if the pets are left outside unattended.

In general, however, experts said foxes should be seen as a positive feature of the urban and suburban landscape. Humans shouldn't try to feed or pet a fox in the back yard, but they shouldn't live in fear of the creature, either.

"It's better that people treat it as an opportunity to observe wildlife," Hodnett said. "Instead of running from it or acting like a hostage in your own home, go get a camera."

Officials said it was probably a fox that killed a National Zoo eagle.