Lately, a lot of them.
Then the calls started.
Pedestrians complained of the stench. There were so many droppings that the sidewalk was slick with them. Some people even abandoned the safer walkway and ventured onto the road shoulder.
Then there were the drivers. A traffic signal is just down the road, and cars wound up stopping under the bridge. Or, more precisely, under the pigeons. Woe betide anyone in a convertible.
In sum, "it was messy and slippery and filthy and disgusting," said commission spokesman Carl De Febo.
The situation was deemed a health hazard. And, however slightly, a bridge hazard. The birds' droppings are so acidic, they can eat away paint and, after many years, start to degrade the structural integrity of the steel and concrete.
There are ways to deal with this, and People for the Ethical Treatment of Animals, tipped to the case by a concerned citizen, praised the commission for its efforts. Partly, for not resorting to poison, which could have been a pointless effort anyway.
"The turnpike did the right thing," said Stephanie Bell, who is based in Washington state and is a casework manager for PETA's cruelty investigations department.
Officials tried a solution that was not only humane but, presumably, reliable and permanent.
The turnpike's contractor called in a subcontractor, Al Zimmerman, owner of Bird Control Inc., which is in Wernersville, west of Reading. Zimmerman travels from Connecticut to North Carolina to take on the toughest birds. This case, he finally concluded, was "complicated."
Last October, workers installed mesh netting to keep birds away from some parts of the bridge. In other parts, they installed plastic "poly spikes" and polished metal "slippery slopes" to keep the birds from landing.
This cost $150,000.
The devices kept some birds out. But others got in, and then couldn't escape. They began dying.
Rick Shearer of Trevose was outraged.
"It's not fair that they're getting stuck somewhere they had the freedom to go before," he said.
The ensuing events that have played out over a period of months involved meetings among engineers, the bird expert, and a PETA person. Investigations were conducted to determine where the breaches might be.
In March, when two young hawks became enmeshed, the fire department came and cut them out.
Twice, repairs were made. But alas, that's not as simple as just trotting over with a ladder. Officials had to close lanes on heavily traveled Street Road. It cost $12,000 over two days for the workers and safety devices, such as cones and flashing arrows.
What makes things more irksome is that pigeons are a problem of our own devising.
Courtney Humphries, in her recent book, Superdove: How the Pigeon Took Manhattan . . . and the World, explains that the classic urban pigeon is relatively new to this country. Humans imported it - for food, and more.
The New World proved more hospitable than anyone expected. Cities' older buildings, with a vast supply of ledges and hollows, make excellent nesting places. As do bridges, apparently.
Once a pigeon decides it likes a place, it keeps coming back. Its homing abilities are legendary.
Bird-proofing is an "uphill battle," Humphries said. She lives in Boston, where poly spikes are popular. But "pigeons just put their nests behind the spikes," she said. "Actually, it kind of helps. The spikes shore up the nests."
Pigeons also stay where there's food.
Sure enough, along the way in Bensalem, officials discovered that someone was feeding the bridge pigeons.
Feeding pigeons is so effective at keeping them around that many cities, including Philadelphia, have laws against it, with fines.
Clearly, pigeons are survivors.
"They're very adaptable," Zimmerman said. "When you try to build them out of their house, they're going to try to get back in. They'll keep trying. They don't go to work or watch TV. They have just a couple things in mind: That's nesting, feeding, and shelter."
This was all new to the Turnpike Commission. "We coexist with flora and fauna all over Pennsylvania," De Febo said. "We've had issues with bats in tunnels, challenges with frogs and snails. But not, that I know of, with pigeons."
PETA officials are trying to be reasonable.
"I want to make it very clear I do think they have done a lot," Bell said. "They certainly have not turned a blind eye to this problem."
PETA does not oppose wildlife-control efforts, she said. "Our emphasis is, the efforts need to be humane. If they're not working correctly and, as a result, are inhumane, we have a problem with that."
PETA's Desiree Acholla of Yardley visited the site yesterday and found about 10 dead birds and half a dozen trapped but still alive.
"You can see dead bodies caught between the mesh and the ledge," she said. "They either died of exposure or starvation. Their wings are stretched upward."
Further, she said, this hardly solves the sanitation issue. If feces alone were bad, "you now have feces and dead bodies." She and Bell want workers to try again.
But turnpike officials, already out $162,000, want to move on.
"I don't want people to think we're a bunch of meanies," De Febo said. "But we're a public entity, we spend public money, and we have to focus on motorist safety and safety of the highway."
He contended the mesh works, "from a public-health standpoint. The droppings are gone. People are keeping to the sidewalk, not stepping into the travel lanes."
He said the agency was all for minimizing entrapments. "But there comes a point when you have to say we've invested sufficient time and money. And I guess we've reached that point."
PETA, meanwhile, called the governor's office.
Friday, that office all but punted.
"Clearly, the turnpike did what it could to deal with the issue in the most humane way possible," said spokesman Chuck Ardo. "We are not in a position to guarantee the quality of life for any given bird."
Contact staff writer Sandy Bauers at 215-854-5147 or email@example.com.