A third eagles nest in Phila.

And now there are three.

The region buzzed with excitement two years ago when a pair of eagles was discovered nesting at the Navy Yard.

The first eagles to nest in the city in more than 200 years, they were hailed as dramatic evidence that the species, once headed for extinction, had begun to recover.

This year, the city has three eagles' nests.

Officials expect the Navy Yard eagles to return to their nest near the Delaware River, perhaps within days.

Another pair has built a five-foot nest in a remote area of Pennypack Park in the Northeast.

And over the last few weeks, birders have seen a pair of young adults taking sticks to a large oak tree on an island at the John Heinz National Wildlife Refuge at Tinicum.

"I think they've become a bit cosmopolitan," said refuge spokesman Bill Buchanan.

For one of the largest cities in the country to be hosting three nests is a development that officials find both encouraging and worrying.

"Here in this urban city, we have habitat that provides nesting areas for eagles," marveled Debby Carr, director of environmental education for Fairmount Park. "It really makes you feel like you're doing something right."

But how will the eagles manage with people so keen to see the birds that they might wind up disturbing them?

"It's one of those things where, too much love and you lose it," said Pete Kurtz, environmental educator at the Pennypack Environmental Center. "You've got to be very careful."

Fortunately - for the birds, if not for eager onlookers - all three nests are in remote areas. And the Navy Yard has restricted access.

But at the Heinz refuge, the birds are easily visible with binoculars or a spotting scope from both a walking trail around the impoundment and a lookout by the water's edge.

Officials welcome onlookers who stick to the paths, but plan to step up enforcement patrols to make sure the birds aren't disturbed.

At Pennypack, signs will be posted advising anyone who strays near the nest that it is a restricted area.

But there, too, the nest is visible from a long way away, said Tom Witmer, director of natural resources for Fairmount Park. So people shouldn't have to get close enough to disturb the birds.

Although eagles were removed from the federal endangered-species list two years ago, they are still on the state list, and it remains a violation of federal law - with potentially hefty fines - to disturb one of the birds.

In 2003, a father and son from Pennsburg who scared away a pair of eagles by entering a restricted area at Green Lane Park in Montgomery County on all-terrain vehicles were fined $1,000 each and sentenced to community service.

The national symbols declined after widespread use of the insecticide DDT, which caused many birds' eggshells to thin. By 1983, just three nests remained in Pennsylvania. That year, the state began a reintroduction program, releasing 88 Canadian birds over the next seven years.

As of last summer, said Pennsylvania Game Commission spokesman Jerry Feaser, the state had more than 150 nests - a modern record - and eagles were nesting in 47 of the state's 67 counties.

In 2008, New Jersey had 69 nesting pairs, also an all-time high since the birds' decline, according to a report released last month. Most are in South Jersey.

Eagles have been seen fishing all along the Delaware River - as well as at Tinicum - in recent years. But this is the first time the birds have nested at the refuge near the airport since its founding in 1972.

The Tinicum nest seems a bit tenuous. The birds are young adults, and have carried just about a dozen sticks out to the tree.

"It's a pretty shabby-looking nesting attempt," said Buchanan.

Whether the female actually lays eggs this winter - February is typical - and whether the eggs will hatch are questions that have prompted much speculation.

"It's still a neat thing to see," Buchanan said. "We're keeping our fingers crossed."

Refuge manager Gary Stolz has seen eagles engaged in their dramatic courtship display, during which they fly high, lock talons, and tumble through the air. But he's not sure if they were the nesting pair or visiting birds.

Two years ago, the Navy Yard eagles hatched at least one egg, but a few days later the eagles flew off, and when they failed to return, a wildlife official climbed the tree and found only eggshell pieces.

They suspect a raccoon or other large bird ate the young.

Last year, however, another eaglet hatched, grew from fluff to feathers, and learned to shred a fish before leaving in late June to explore the wider world.

Feaser attributed some of the eagles' success to habitat restoration and water-quality improvements that benefit the fish-eating species.

At Pennypack, for instance, a large chunk of filled-in wetlands was recently restored. And two years ago, two dams were removed from the Pennypack Creek, opening up more of the waterway to fish passage.

Likewise, Tinicum over the last decade has completed several major wetlands restorations.

The refuge, which encompasses a Superfund site, still has contamination problems.

"It's an urban area. And, yes, there are things in the water," said Stolz. "But compared to where we were, 40, 50 years ago, it's turning into a Garden of Eden."

Here are tips from Pennsylvania Game Commission ornithologist Doug Gross:

Stay quiet. Converse in hushed voices. Avoid slamming car doors and honking horns. Avoid sudden movements and movements directly toward the eagles or the nest.

The farther away you can stay, the better. Observe eagles from behind an object, such as a blind or a tree or even a vehicle. Stay in the vehicle if possible.

Avoid attempting to make the birds fly. Not only is it a federal offense defined as harassment, it also causes the bird to waste energy or potentially leave behind a valuable meal - or even abandon the nest.

Respect the eagles' reactions to your actions. If they start to act agitated or start moving away, that means you should back away and give them some space.

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