Feral Pigeon - Population Control

Population Control

Feral pigeons often only have small populations within cities. For example, the breeding population of feral pigeons in Sheffield, England, has been estimated at only 12,130 individuals. Despite this, feral pigeons usually reach their highest densities in the central portions of cities, so they are frequently encountered by people, which leads to conflict.

Feral pigeons are often considered a pest or even vermin, owing to concerns that they spread disease and are much maligned in the media for transmitting bird flu, but it has been shown pigeons do not carry the deadly H5N1 strain. Much of the media attention about pigeons carrying disease or causing property damage is attributed to the pest control companies working to drum up business. It is rare that a pigeon will transmit a disease to humans due to their immune system. Three studies have been done since the late 1990s by the US Agriculture Department's Southeast Poultry Research Laboratory in Athens, Georgia, according to the center's director, David Swayne. The lab has been working on bird flu since the 1970s.

In one experiment, researchers squirted into pigeons' mouths liquid drops that contained the highly pathogenic H5N1 virus from a Hong Kong sample. The birds got 100 to 1,000 times the concentration that wild birds would encounter in nature. "We couldn't infect the pigeons," Swayne said. "So that's good news."

The bacteria Chlamydophila psittaci is endemic among pigeons and causes Psittacosis in humans. It is transmitted both from handling pigeons but mostly from their droppings. Psittacosis is a serious disease but rarely fatal (less than 1%). Pigeons are also important vectors for different species of the bacteria Salmonella which causes diseases as Salmonellosis and Paratyphoid fever.

There is ample reason for the concerns of pigeons damaging property, due to their size and proximity to people and their dwellings. Pigeons often cause significant pollution with their droppings, though there is little evidence of them driving out other bird species. Pigeons are labeled an invasive species in North America by the USDA.

While pest exterminators use poison, hawks and nets have also been employed at ground level to control urban pigeon populations, though this generally achieves only a limited, temporary effect.

Long-term reduction of feral pigeon populations can be achieved by restricting food supply, which in turn involves legislation and litter (garbage) control. Some cities have deliberately established favorable nesting places for pigeons—nesting places that can easily be reached by city workers who regularly remove eggs, thereby limiting their reproductive success. In addition, pigeon populations may be reduced by bird control systems that successfully reduce nesting sites.