Pigeons breed when the food supply is good—for wild rock doves this might be seasonally so they usually breed once a year. In the wild they are often found in pairs in the breeding season but usually they are gregarious. In the urban environment, because of their year-round food supply, feral pigeons will breed continuously, laying eggs up to six times a year.
Feral pigeons can be seen eating grass seeds and berries in urban parks and gardens in the spring, but there are plentiful sources throughout the year from scavenging (e.g. dropped fast-food cartons) and they will also take insects and spiders. Further food is also usually available from the disposing of stale bread in parks by restaurants and supermarkets, from tourists buying and distributing birdseed, etc. Pigeons tend to congregate in large, often thick flocks when going for discarded food, and many have been observed flying skillfully around trees, buildings, telephone poles and cables, and even moving traffic just to reach it.
As a result of the continuous food supply, pigeon courtship rituals can be observed in urban parks at any time of the year. Males on the ground initially puff up feathers at the nape of the neck to increase their apparent size and thereby impress or attract attention, then they single out a female in the vicinity and approach at a rapid walk while emitting repetitive quiet notes, often bowing and turning as they approach. Initially, females invariably walk away or fly short distances, the males follow them at each stage. Persistence by the male will usually eventually cause the female to tolerate his proximity, at which point he will continue the bowing motion and very often turn full- or half-pirouettes in front of the female. Subsequent mating when observed is very brief with the male flapping his wings to maintain balance on the female. Sometimes the male and female beaks are locked together.
Nests are rudimentary as for the wild doves and pigeons. Favourite nesting areas are in damaged property. Mass nesting is common with dozens of birds sharing a building. Loose tiles and broken windows give pigeons access; they are remarkably good at spotting when new access points become available, for example after strong winds cause property damage. Nests and droppings will quickly make a mess of any nesting area. Pigeons are particularly fond of roof spaces, many of which accommodate water tanks, though they frequently seem to fall into the tanks and drown. Any water tank or cistern in a roof space needs to have a secure lid for this reason. The popularity of a nesting area seems little affected if pigeons die or are killed there; corpses are seen among live birds, who seem unconcerned.
On undamaged property the gutters, window air conditioners (especially empty air conditioner containment boxes), chimney pots and external ledges will be used as nesting sites. Many building owners attempt to limit roosting by using bird control spikes and netting to cover ledges and resting places on the façades of buildings. These probably have little effect on the size of pigeon populations, but can help to reduce the accumulation of droppings on and around an individual building.
Only the larger and more wary Wood Pigeon (which often shares the same territory and food supply) will build a tree nest; for some reason it prefers trees close to roads.