The Rock Pigeon arrived in North America in the 17th century with settlers who brought them from Europe, and are either much-loved or much hated, depending upon one's point of view. They have thrived alongside mankind in their urban habitats. The occur in a wide range of colors.
Pigeons are monogomous and pair for life. Their ideal nest site is a ledge under cover; hence, the populations under bridges and underpasses. Usually a nest consists of two eggs, although pigeons may overlap broods, by laying the next two eggs as the first two are hatching out. However, due to the number of feedings required and the brooding necessary to maintain body temperature, if something happens to one of the parents the first week after hatching, a single parent cannot feed both babies.
According to Birds of North America online, young begin hatching in February. However, at Wild Bird Rescue, we had a squab in January 2008. However, the same source does note some winter breeding. This is possible because pigeons do not feed insects to their young, but crop milk that they make from the seeds they eat.
Predators include hawks and falcons, racoons, opposums, great horned owls, crows and ravens.
Pigeons are known for their homing capabilities. They appear to rely on both the sun and magnetic fields to find their way.
These are fascinating birds that have fallen into disfavor due to the large flocks that tend ot congregate (and defecate) in urban areas.