The black-crowned night heron or black-capped night heron (Nycticorax nycticorax Linnaeus, 1758) is a bird belonging to the Ardeidae family.
From a systematic point of view it belongs to:
N. nycticorax species.
The term is synonymous:
– Ardea nycticorax Linnaeus, 1758.
Within this species, four subspecies are recognized:
– Nycticorax nycticorax nycticorax (Linnaeus, 1758) – which populates Eurasia, including the Malay archipelago, Africa and Madagascar;
– Nycticorax nycticorax hoactli (Gmelin, 1789) – which lives from southern Canada to central Argentina and northern Chile;
– Nycticorax nycticorax obscurus Bonaparte, 1855 – which occupies central and southern Chile and southern Argentina up to the Tierra del Fuego archipelago;
– Nycticorax nycticorax falklandicus Hartert, 1914 – endemic species of the Falkland Islands.
Geographic Distribution and Habitat –
The black-crowned night heron is a cosmopolitan bird, also due to its subspecies and is present almost all over the world except in Oceania.
The reproductive habitat of this species is the wetlands of fresh and salt water in much of the world. The subspecies Nycticorax nycticorax hoactli nests in North and South America, from Canada to northern Argentina and Chile; the subspecies Nycticorax nycticorax obscurus lives in the extreme south of South America; the subspecies Nycticorax nycticorax falklandicus is an endemic species of the Falkland Islands, and the nominal race Nycticorax nycticorax nycticorax lives in Europe, Asia and Africa.
This heron is migratory in the northernmost part of its range, but otherwise resident (also in the cold Patagonia). The North American population winters in Mexico, the southern United States, Central America, and the West Indies, while Old World birds overwinter in tropical Africa and South Asia.
These birds nest in colonies on stick platforms in a group of trees, or on the ground in protected locations such as islands or reeds, in saltwater wetlands, across much of the planet. They therefore frequent swampy areas, rivers, streams and the banks of small lakes.
The Nycticorax nycticorax is a bird with a length of 58 – 65 cm, a wingspan of 95 – 112 cm, for a weight of 730-1.010 grams, which does not have sexual dimorphism.
The coat is white, the neck is short and the beak is dirty yellow tending to brown. The back is gray, as is the head. The wings are greyish, lighter than the back. The eye of a very bright red color stands out. The legs are relatively short, yellow.
In the juvenile stage the body color is much more uniform, amber brown and flecked with white. In addition, the eye is yellow-orange in color.
The black-crowned night heron is a migratory, gregarious species that nests in very numerous colonies, even consisting of hundreds of individuals, and often shares the heronries with other species of herons, mostly egrets. The female lays, between May and June, 3-5 (up to 8) light blue-green eggs, brooded by both parents for about 26-27 days. The young are looked after by their parents for the first two weeks, after which they are able to take flight and feed themselves.
These herons arrive in the nesting areas in March. Males begin the complex mate selection ritual before the nest is built. Once the pair is established, the nest is built in a tree or bush about four or five meters high. The nest is a simple structure of sticks, branches and other elements.
Ecological Role –
The Nycticorax nycticorax is a gregarious species throughout the year. In winter, it is collected during the day in dormitories that can number several dozen individuals. It has purely nocturnal habits, even if it can hunt also during the day, usually waiting for the prey to pass near its stalking. It generally hunts in shallow water by grabbing prey with its strong beak.
The diet is varied and consists of fish, amphibians, worms, insects, reptiles, small mammals.
This species, like many others, is affected by the transformation of the nesting and feeding habitat and by problems in the wintering areas.
It has been in decline in the last 15 years due, in the areas where it coexists, to the competition for resources with Ardea cinerea, which had a significant increase in population in the same period.
This species, in Europe, is listed in Annex I of the Birds Directive (79/409 / EEC).
– Wikipedia, the free encyclopedia.
– C. Battisti, D. Taffon, F. Giucca, 2008. Atlas of nesting birds, Gangemi Editore, Rome.
– L. Svensson, K. Mullarney, D. Zetterstrom, 1999. Guide to the birds of Europe, North Africa and the Near East, Harper Collins Publisher, UK.