Living environment and biology of the species
The Black-Crowned Night Heronfeeds in areas with lakes, large streams, ponds, shallow vegetated channels, ponds, at the edge of water bodies, in areas rich in marsh vegetation. Nests in trees in wet areas such as meadow forests, willows in reed beds, aspen plantations. In Romania, as in all of southern Europe, the nightjar is a summer guest. At the end of the nesting season it disperses over large areas.
It flies mainly at night or during twilight periods, hence the name given to the species, the nightjar (Nycticorax nycticorax). Both the genus name and the specific epithet come from the Greek words nyx/nyctos – night, respectively korax – raven, referring to the nocturnal activity of the nightjar and its raven-like sounds. During the day it retreats into trees or bushes. They feed solitarily, but can sometimes be seen flying in small groups during the nesting season. Outside the nesting season, nightjars gather in flocks that can comprise hundreds of individuals. Sexual maturity is reached at two years of age.
Food consists mainly of small fish, but they also eat amphibians, leeches, tadpoles and insects. They hunt mainly at dusk, early or late in the day.
Black-Crowned Night Heron return to nesting areas in late March, early April. Rarely, some individuals remain in the Danube and Delta area.
During the nesting period, the Black-Crowned Night Heron is a monogamous species. It nests in monospecific or mixed colonies with cormorants and other species of terns. Nests are built in trees. Adults mate near the nest site from the first days of pair formation. Both parents help build the nest, which is made of twigs and reeds in the shape of a shallow dish. Towards the end of April, the female lays 2-3 blue-green eggs, which are incubated in turn by both parents for 21-22 days. The change to the nest involves a ritual that includes movements to display the plumage. The chicks are fed by both parents until they become independent. At 50-60 days of age, the chicks leave the nest, but remain in close proximity to the nest, waiting for food from the adults. The parents do not always recognise their own chicks, so it happens that they also bring food to chicks from neighbouring nests, especially to those that insistently beg for food.