Reproduction
Sexual Maturity
Flamingos reach reproductive age after three years. Studies of populations in the wild found that birds six years or older had a higher rate of breeding success than younger birds. Sexual maturity is evidenced by the gradual molt of the chick from light pink plumage at one year, to the deep pink coloration characteristic of a sexually mature adult at two to three years.
Breeding Season
Flamingo colonies in Mexico typically breed in May, while flocks in the Bahamas breed March through June. Breeding can be highly irregular, and may not occur every year. In the wild, breeding season is linked to sufficient rainfall. Sufficient rainfall creates areas with adequate food supplies. The rains also create wet mud, which is essential for nest building. Ample rainfall also floods the nesting area thus excluding land predators from the breeding site.
At the National Zoo, the breeding season typically begins in early January with the onset of the breeding displays. Peak displays occur during February and March. Eggs are usually laid in May or June, with chicks hatching a month later.
Courtship
Flamingos have an elaborate series of breeding displays that are performed by both sexes. The purpose of these displays is to bring the entire flock into reproductive synchrony. By doing so, the majority of the eggs are laid at the same time. Consequently, most of the chicks hatch at a time when environmental conditions are most favorable for their survival.
The breeding displays begin several months before the actual arrival of eggs. These highly ritualized displays are performed by all six species of flamingos, although each species differs in how each display is performed. For the American flamingo, the sequence begins with head flagging. This involves stretching the neck and head upward while at the same time flagging it rapidly back and forth, and vocalizing loudly. Head flagging is followed by the wing salute. In this display, the wings are spread out to the side of the body and held in this position for several seconds. The contrasting black flight feathers are highly visible in this display. The display referred to as twist preen follows next, and involves twisting the head backward behind one wing, as if the bird were preening itself. An inverted wing salute is performed next. Here, both wings are flipped over the front of the bird while at the same time, stretched out. The wing-leg stretch is the final phase of the display sequence. In this display, one wing and one leg on the same side of the body, are stretched backwards. The entire sequence from start to finish takes only seconds to perform, before the whole chain begins over again.
Pictures showing courtship display
Flamingos are monogamous and pair bonds are constantly reinforced throughout the year. Bonds are maintained through vocalizations and by feeding side by side. A pair works together to fend off an attack from another bird or birds. If the pair bond is broken (usually the result of death), the surviving flamingo forms a new bond with another bird. Exactly how this new bond develops is not fully understood.
Copulation
Copulation begins several days after a pair ceases displaying. The pair venture off from the flock, and the female invites the male to copulate with her. Copulation is performed in the water. The female initiates the event by walking in the water and often submerging her head. While her head is submerged, she spreads her wings. The male jumps on her back and flaps his wings to maintain balance. Once copulation is complete, the male dismounts by jumping in front of the female.
Nesting behavior
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Both parents assist in the construction of the nest. The male usually begins the process of shaping the nest. The female takes over the task as the egg is developing in her body.
As the time of egg laying approaches, both parents work rapidly to complete the nest. Even after the arrival of the egg, nest building continues as the pair works to perfect the nest site.
Incubation
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The normal clutch of eggs for all species of flamingo is one. Very rarely are two eggs laid, and it is thought that when this occurs, two different females may be involved. Egg measurements and weights vary widely between individuals, but on average, they weigh 140 grams (five ounces) and measure 90 x 55 millimeters (about 3.5 x 2 inches). Immediately after laying, the egg is pure white with a chalky texture. Soon after, however, the egg is often marked with mud from the nest site. Chicks enter the air cell at day 26, followed by pipping at day 27. Hatching generally occurs two days after the chick has entered the air cell.
Infant Mortality
In the wild, American flamingo chicks are most susceptible to avian predators. Mammalian predators will take chicks if the protective mud flats dry up. Estimates of a 30-percent mortality in the first year have been given. Egg removal in Mexico by local people once significantly affected the population, but federal regulations now prohibit this act. In the Bahamas, villagers previously rounded up newly hatched chicks to sell in town, until laws were enacted to prevent this. Flooding and hurricanes have caused the desertion of entire nest sites. Disturbances to breeding flocks from tourists flying overhead in airplanes and or approaching in motorboats are currently a serious problem.
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