Feral pigeons (Columba livia domestica), also called city dove, city pigeon, or street pigeon, are all derived from domestic pigeons that have returned to the wild. The domestic pigeon was originally bred from the wild rock dove, which naturally inhabits sea-cliffs and mountains. Rock, domestic, and feral pigeons are all the same species and will nearly always interbreed. Feral pigeons find the ledges of commercial and Industrial buildings and domestic houses as a substitute for sea cliffs and have become adapted to urban life, and are aplenty in towns and cities throughout much of Australia and the World.
With domesticated populations, feral pigeons mate for life. Their courtship rituals can be observed in suburban parks through the year. The male on the ground or rooftops puffs up the feathers on the neck to appear larger and thereby impress or attract attention to the female. He approaches the hen at a rapid walking pace while emitting repetitive quiet notes, often bowing and turning as he comes closer. At first the female invariably walks or flies a short distance away and the male follows her until she stops. At this point he will continue the bowing motion and very often make full- or half-pirouettes in front of the female. The male will then proceed to feed the female by regurgitating food, as they do when feeding the young. The male then mounts the female, rearing backwards to be able to join their cloacas. The mating is very brief with the male flapping his wings to maintain balance on top of the female.
Abandoned buildings are favorite nesting areas. Mass nesting is common as pigeons are a community flocking bird; often dozens of birds will share a building. Loose tiles and broken windows provide access, and pigeons are adept at spotting new access points, for example following property damage caused by strong winds. Nests and droppings tend to stay clustered and remain dry when out of the weather. Pigeons are particularly fond of roof spaces. These often contain water tanks. Any water tank or cistern on a roof must therefore be secured and sealed off to keep the pigeons out of them. The popularity of a nesting area does not seem to be affected by the pigeons’ population density. Pigeon squab in nest On undamaged property, the gutters, window air conditioners and empty air conditioner containers, chimney pots and external ledges are used as nesting sites. Many building owners try to limit roosting by using bird control spikes and netting to cover ledges and potential nesting places on buildings. This has little effect on the size of the pigeon population, but it can reduce the accumulation of droppings on and around a particular building location.
Pigeons breed when the food supply is abundant enough to support embryonic egg development, which in cities can be any time of the year. Laying of eggs can take place up to six times per year. Pigeons mate for life, and are often found in pairs during the breeding season, but usually the pigeons are gregarious preferring to exist in flocks of from 50 to 500 birds .Feral pigeons can be seen eating grass seeds and berries in parks and gardens in the spring, but there are plentiful sources throughout the year from scavenging (e.g., remnants left inside of dropped fast-food cartons) and they will also take insects and spiders. Additional food is also usually available from the disposing of stale bread in parks by restaurants and supermarkets and from tourists buying and distributing birdseed, etc. Pigeons tend to congregate in large, often thick flocks when feeding on discarded food, and have been observed flying skillfully around trees, buildings, telephone poles and cables, and even through moving traffic just to reach a food source.
Feral pigeons usually reach their highest densities in the central portions of cities, so they are frequently encountered by people, which leads to conflict. Large pigeon trap/coop/loft at Batman Park, Melbourne. Designed specifically to encourage nesting and allow removal of fertilised eggs to prevent population growth, it is a landmark in its own right. One of the difficulties of controlling pigeon populations is the common practice of feeding them, as here in New York 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. 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
A more effective tactic to reduce the number of feral pigeons is deprivation. Cities around the world have discovered that not feeding their local birds results in a steady population decrease in only a few years. Pigeons, however, will still pick at garbage bags containing discarded food or at leftovers carelessly dropped on the ground. Feeding of pigeons is banned in parts of Venice, Italy.
In 1998, in response to conservation groups and the public interest, the National Wildlife Research Center (NWRC), a USDA/APHIS laboratory in Fort Collins, Colorado, started work on nicarbazin, a promising compound for avian contraception. Originally developed for use in resident Canada geese, nicarbazin was introduced for use as a contraceptive for feral pigeons in 2007. The active ingredient, nicarbazin, interferes with the viability of eggs by binding the ZP-3 sperm receptor site in the egg. This unique contraceptive action is non-hormonal and fully reversible. Registered by the EPA as a pesticide (EPA Reg. No. 80224-1), “OvoControl P”, brand of nicarbazin, is increasingly used in urban areas and industrial sites to control pigeon populations. Declared safe and humane, the new technology is environmentally benign and does not represent a secondary toxicity hazard to raptors or scavengers. Avian contraception has the support of a range of animal welfare groups including the Humane Society of the United States (HSUS), the American Society for the Prevention of Cruelty to Animals (ASPCA) and People for the Ethical Treatment of Animals (PETA).