Reproduction and breeding biology
Northern Bald Ibises breed in colonies, but they are not necessarily monogamous. During the breeding season they develope close partnerships, which can change in the following year. The partners both participate in the building of the nest, the breeding and the raising of the young.
Usually, Northern Bald Ibises lay up to four eggs, which are of a greenish colour and the size of a chicken´s egg. The parents breed from the first laid egg, so that the young hatch within intervals of one to three days. Thus, a rank order within the nestlings is developed and the aggression among the chicks is reduced. Northern Bald Ibises are great parents and also care enough for the youngest bird in the nest.
The nestlings are fully fledged after 42 to 50 days. Then they join their parents to search for food and later they ally with other young birds of their age to small coveys. During their first autumn migration they join experienced fellows and thereby learn to know the wintering area. Thus, the genetically fixed urge to migrate is added by a traditionally passed-on knowledge of a proper wintering area.