Black-crowned Night-Heron (Nycticorax nycticorax)

Black-crowned Night-Heron

Description

The black-crowned night heron (Nycticorax nycticorax), or black-capped night heron, commonly shortened to just night heron in Eurasia, is a medium-sized heron found throughout a large part of the world, except in the coldest regions and Australasia (where it is replaced by the closely related nankeen night heron, with which it has hybridized in the area of contact). Adults have a black crown and back with the remainder of the body white or grey, red eyes, and short yellow legs. They have pale grey wings and white under parts. Two or three long white plumes, erected in greeting and courtship displays, extend from the back of the head. The sexes are similar in appearance although the males are slightly larger. Black-crowned night herons do not fit the typical body form of the heron family. They are relatively stocky with shorter bills, legs, and necks than their more familiar cousins, the egrets and "day" herons. Their resting posture is normally somewhat hunched but when hunting they extend their necks and look more like other wading birds.

Distribution And Habitat

The Black-crowned Night Heron occurs worldwide. It is an uncommon resident species in Puerto Rico (Oberle 2018, Raffaele 1989a) and considered a rare spring resident on Vieques where breeding is unconfirmed (Gemmill 2015). In addition, it also occurs in Mona (Ventosa- Febles and others 2005). This species inhabits freshwater swamps, but also uses brackish lagoons and salt ponds (Raffaele and others 1998). It is mostly nocturnal and usually seen at dawn or dusk (Oberle 2018, Raffaele 1989a). The atlas fieldwork yielded a total of 75 records within 60 hexagons or 13 percent of the 479 total hexagons (see map). Of the 60 hexagons where this species was found, breeding met the atlas definition of confirmed in 5 percent (3) of the hexagons, probable in 2 percent (1), and possible in 37 percent (22), while the species was observed in 57 percent (34) of the hexagons but without evidence of breeding (see map). Black-crowned Night Heron distribution. The map shows the highest breeding code by hexagon and overlaying the ecological life zones in Puerto Rico. Note: percentages may not total 100 due to rounding.

Breeding Habits

The Black-crowned Night Heron nests in colonies, and nests are built on trees mainly from January to late July, but breeding 159Black-crowned Night-Heron/Yaboa Real season may vary, according to previously published reports (Raffaele and others 1998). Atlas results indicate that the peak of the breeding season for this species is from April to June (see chart). Results show that this species breeds in the subtropical moist forest life zone (58 percent of the hexagons), subtropical dry forest life zone (27 percent of the hexagons), and subtropical wet forest life zone (15 percent of the hexagons) (see table and map).14 percent or 86 km2 of the total area covered by the hexagons where evidence of breeding was found for this species (622 km2).

Conservation

The Black-crowned Night Heron is listed as a species of least concern by the IUCN (BirdLife International 2019). Locally, this species is not listed in any of the threatened categories of PRDNER and USFWS. Locally, this species is not listed in any of the threatened categories of PRDNER and USFWS. In Puerto Rico, the Black-crowned Night Heron has a protected habitat in land of