Life History and Reproduction

The life cycle and reproductive process of the yellow-crowned night heron is typical of other birds, however, many behaviors throughout the growth and maturation of the night heron differ from other species.

YCNHIn preparation for reproduction, yellow-crowned night herons assemble nests of sticks. Both the male and female heron assist in nest construction (Bagley and Grau 1980). They typically build their nests about 15 meters above ground (Watts 1989); nesting high in trees allows for evasion of predators on land, which is a major source of offspring loss (Wischusen 1980). Nyctanassa violacea parents also prevent predation of their young, as well as mate and material theft, by facing opposite directions in the nest. Nest mates that face different directions while nesting have a greater range of threat surveillance, and therefore, greater reproductive success and a reduced risk of being attacked. Those that do not face opposing sides of the nest have greater odds of predation, a diminished probability of protecting their young, and a smaller chance of passing on their genes to the next generation (Afkhami and Strassmann 2007).

Like all birds, yellow-crowned night herons undergo sexual reproduction. Once the eggs have been fertilized and laid, they have to be incubated until they are ready to hatch. Contrary to some avian species, both the male and female heron will incubate the eggs (Bagley and Grau 1980). When the young herons hatch, the paternal herons feed the offspring a mixture of small crab and insect pieces that are similar to the adult diet (Watts 1988). Both the male and female heron feed their young, a behavior not found in some bird species (Bagley and Grau 1980). Though yellow-crowned night herons become independent from their parents within four to nine weeks of birth, they will not develop adult plumage necessary for mating until they reach two years of age (Wingate 1982).
When the herons reach reproductive age, they begin searching for a mate. Yellow-crowned night herons are monogamous, so finding a mate is an important task (Afkhami and Strassmann 2007). These night herons use several behaviors, such as vocal calls, flying patterns, and displays in mate attraction. When two birds decide to mate, the male mounts the female and insemination occurs. Fertilization of the eggs occurs within the female, where they will develop until they are ready to be laid. Then the chicks will hatch, grow, and sexually mature until reproduction occurs and the cycle will begin again (Bagley and Grau 1980).

Though the life cycle of the yellow-crowned night heron relates to other avian species, there are key behavioral and procedural differences in nesting, feeding, mating, and incubating habits in the life and reproductive cycles of these birds. As you will see on the next page, some of these behaviors of the yellow-crowned night heron impact the interactions it has with other species.