Its shape and size are similar to those of the white or common stork, from which it differs by its lustrous black plumage with white underparts. The young have the feathers of the head, neck and matte brown crop, with light tips; above they are dark brown with almost no reflections. There is no sexual dimorphism. Less popular than the white stork because of its solitary habits and scarcity, the black stork is a typically mountainous and wild bird. The peculiarities of their biology have reduced them to the most remote areas of our geography, which on the one hand are the least inhabited, and on the other, provide them with the special places they need for nesting: dense forests of oak, cork oak or pine trees and, in deforested areas, large cliffs that are difficult to access. In either biotope, the proximity of abundant water is essential, be it rivers, ponds or artificial reservoirs. In their breeding area, black storks appear during the months of February and March. Couples, probably united for most of the year, make long nuptial flights. It occupies nests from previous years or both sexes build a bulky nest of branches with local materials, delicately lined with mosses, green herbs and grasses, in cork oaks, oaks, pines and more frequently on cliff ledges, always close to water. The laying, from April to June, consists of 3 to 5 white eggs. Incubation, carried out by both sexes, lasts from 38 to 42 days. The chickens, fed by both parents, leave the nest at 65-70 days. After reproduction, the birds leave the breeding areas and concentrate in large groups, in some favourable roosting areas. It feeds on fish, water snakes, frogs, water rats; insects, such as beetles, females and dragonflies; some plant matter.