Where have all the pigeons gone? Philly numbers are down as predators thrive. Could it be a trend?

Pigeons once so ruled the roost in Philadelphia that the city resorted to broadcasting tapes of pigeons in distress and having police fire blanks into the air in an effort to scare them off City Hall.

But Robert Tunick says that these days he has noticed a significant decline in the pigeon population in the city and wondered if he could believe what he hasn’t been seeing.

“What happened to all the pigeons in Center City?” asked Tunick, an Inquirer reader who contacted Curious Philly, our Q&A forum that allows readers to send us queries about topics piquing their interest. Has their population actually decreased?

For decades the city has waged a sometimes costly battle against these rainbow-necked urban nemeses. No truce has been declared, but could the fight be ending peacefully?

Pigeon-counting isn’t quite as detailed or politically charged as the nation’s decennial human census, but the available data suggest that Tunick might well be onto something.

The number of pigeons counted in the Mid-Winter Philadelphia Bird Census has dropped dramatically, according to Keith Russell, the ornithologist in charge of the bird count, which occurs every year in January.

In 1993, 57 participants observed 2,437 rock pigeons, the species of pigeon that’s most commonly found in cities. That was 43 per observer. In 2017, 92 participants observed just 288 rock pigeons, or 3 per observer.

As scientists are wont to do, Russell, who lives in Germantown and is the Urban Conservation Project manager at Audubon Pennsylvania, cautions against reading too much into the data. He points out that the citywide surveys were conducted with fluctuating numbers of observers and under diverse weather conditions.

For example, during the Jan. 7, 2017, survey, 3 inches of snow fell on the city between 9 a.m. and 3 p.m., according to the National Weather Service. But the 92 participants that day were the most in the history of the surveys, which began in 1987.

So why would the number of pigeons in Philadelphia be dwindling?

Russell speculated that the decrease might be related to an increase in raptors; raptors feast on pigeons. Separate data indicate greater numbers of peregrine falcons, Cooper’s hawks, and especially red-tailed hawks -- which in annual censuses jumped from 20 in 2017 to 68 in 2019.

While the decline of the pigeon population is hardly a cause for mourning for most city residents, pigeons have real value to urbanites, Russell mentioned. Pigeons are scavengers, which means that they eat leftovers that might otherwise be consumed by animals like rats, he said.

And they are smarter than they look. According to Charles Walcott, professor emeritus at Cornell University, pigeons originally inhabited environments full of cliffs but have adapted nicely to city life, using skyscrapers as “a pretty good substitute” for cliff life.

During World War I, the United States and Britain used homing pigeons — a specially bred and domesticated kind of rock pigeon — to carry secret messages to other Allied troops, since homing pigeons are able to fly back to their home lofts from hundreds of miles away. Scientists have hypothesized that the birds accomplish such a feat by sensing Earth’s magnetic field and using it for guidance.

But Philadelphians should feel no pressure to swell the ranks of rock pigeons.

They are non-native, originally coming from Europe and Asia, and according to Walcott, were originally brought here for food.

In fact, a city ordinance prohibits the feeding of pigeons “in any public street, square, park, or place of public resort.”

What’s more, pigeon manure can transmit diseases to humans.

And their droppings can be costly. In the 1970s, the city used to pay the equivalent of nearly $200,000 annually in today’s dollars to keep pigeons away from City Hall. At one time several years ago, the city paid to remove 100,000 pounds of pigeon droppings from City Hall.

Philadelphia and the rock pigeon have a long and acrimonious history. In the late 1950s, the city tried the equivalent of knockout drops. It placed bird seed coated with a chemical on City Hall grounds in attempt to tranquilize the birds, after which they would be relocated. But the program was halted after only a month, after it was discovered that pigeons were actually passing out in midflight and crashing onto the street, where they were run over.

Another attempt literally shot blanks.

Police officers fired blanks to scare away pigeons, but that was axed after officials realized that the blanks were scaring pigeons into flying up, where they “blessed the crowd with their droppings,” according to a June 1987 Inquirer article.

City officials also abandoned plans to play tapes of pigeons in distress and apply sticky goo to the ledges of City Hall after realizing they didn’t work.

Philadelphia isn’t the only city to wage war on pigeons. In 2013, the government of the Spanish city of Cádiz relocated 5,000 pigeons hundreds of miles away after the birds were seen as a menace to tourists. In 2017, the City Council of San Clemente, Calif., proposed spending $375,000 to keep the city’s pier pigeon-free.

But despite pigeons’ ability to irritate almost everyone, Russell hopes that Philadelphians can come to respect their avian cohabitants.

“They’re here to stay, so we need to understand them and appreciate them.”