BREEDING AND NESTING
During the breeding season, many male birds acquire their brightest plumage and sing their most seductive song to attract a mate. The males of some species perform elaborate courtship displays. Eventually, the female bird chooses to accept or reject the male. Once the two are bonded as a pair, nest building and the raising of young can begin. Most birds breed during the warmer months to take advantage of longer days and the greater availability of food.
Defending a Territory
Breeding usually begins with a careful selection of a territory. The area must offer access to food and safety from predators.
Billing involves an elaborate set of gestures and helps birds establish a relationship as a pair. The Atlantic Puffin has just the bill for the job.
The copulation display of the White-throated Swift may be the most dramatic in North America. The swifts approach each other from opposite directions at a high altitude and mate while tumbling through the air.
Do they mate for life?
This is an often-asked question. We like to imagine that birds possess those qualities of fidelity and loyalty that we value in humans. Most birds make bonds that last through the breeding season. But, once the young are fledged, that connection usually ends. Some birds form no bonds and will mate with several partners in one season. Other birds swans, for example form bonds that last for life.
In North America, most nesting and raising of young is done in the summer to take advantage of long days and warm temperatures. The nest must be properly placed for protection from predators. Birds build an enormous variety of nests, from tiny camouflaged cups of twigs and grass to huge stick formations large enough to hold a person. Birds' eggs come in a variety of colors and sizes. The incubating parent, usually the female, may develop a bare spot or brood patch on its belly to allow its body heat to incubate the egg. Once out of the shell, some hatchlings are on their own. Others keep their parents busy feeding and raising the hungry family.
Selecting a Site
Each species has its own particular choice of nest sites. One criterion in site selection is safety from predators. Common Murres lay their eggs on the ledges of sheer cliff faces.
Building a Nest
There are nearly as many varieties of nests as there are varieties of birds. Intricately woven oriole nests hang from tree branches.
In some species the male helps with the incubation of eggs. In the case of the Wilson's Phalarope, the male does all the incubation of eggs and the tending of young.
Some birds are nearly self-sufficient when they hatch. Precocial Killdeer feed themselves just a few hours after emerging from the shell. Most shorebirds must feed themselves from birth.
How long do birds live?
There are records of birds in captivity living 50, 60, and even 70 years, including condors, eagles, hawks, owls, pelicans, and parrots. In the wild, albatrosses often exceed 40 years, some gulls 30, and certain waterfowl and hawks, 20 years. Typical songbirds, however, probably live 2-5 years.