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Black-crowned Night-Heron
Nycticorax nycticorax

DESCRIPTION:
Black-crowned Night-Heron
Garza Bruja
Nycticorax nycticorax
Length: 650mm. Sexes alike. Bill black; bare skin on lores bluish; eyelids greenish; iris red, forehead white; top of head black with greenish gloss; rest of head and neck brownish grey except chin; throat, top part of fore neck and thin band extending from base of mandible to postorbital area white; has very long and fine white nape plumes that when neck is retracted extend on back. Upper back and scapulars black with greenish sheen; lower back, rump and uppertail coverts, brownish grey; primaries and secondaries brownish grey; underside of wings brownish grey slightly lighter on coverts than on remiges. Breast, flanks, belly, feathered part of tibia and crissum brownish grey; leg with bare part of tibia, posterior of tarsus and underside of toes, light green; anterior part of tarsus and upperside of toes, greenish brown.
Juveniles: brownish grey bill on upper part of maxilla and green on lower ridge and mandible; iris orange; bare part of lores and eyelids green; top part of head greenish brown with whitish ochraceous spots; rest of head, neck, breast and underparts whitish buff, profusely striated greenish brown; back, wings and tail greenish brown, striated and spotted with whitish ochraceous.
This description corresponds to the race Nycticorax nycticorax obscurus, typical of the Patagonian region. It also has a phase of very dark colouring, as follows: bill black; bare part of lores dark blue; eyelids dark green; iris red; plumage black overall with greenish sheen except fore neck, chest and belly that are dark grey; the fine and long nape plumes are black; legs are dark greenish grey on the tibial area, posterior part of tarsus and underside of toes; front part of tarsus and upperside of toes blackish brown. Juveniles in this phase are dark greenish brown overall with streaks and spotting of yellowish ochraceous. Habitat and behaviour: it inhabits ponds, marshes, rivers, streams and lake margins, preferably with abundant vegetation. Active at dusk and night, during the day it remains concealed, perched on densely branched trees; it becomes active late in the afternoon; resting grounds may sometimes be located far from the water. It can be found both solitary or in pairs, also in groups of few individuals; late in the afternoon when it flies to its feeding grounds it utters a loud hoarse cry that resembles the bark of a dog or fox, the reason why it is also known as Water Fox, Cuaco and other common names. In Patagonia it is known as Huadra or Huairavo, terms of Chilean origin. It mainly feeds on fish, amphibians, reptiles, molluscs, crustaceans, insects and their larvae, small mammals and fledglings of other birds; it stalks its prey by remaining motionless with the neck retracted, usually on the shore or on some convenient perch, and swiftly grasps its prey with its bill. It nests in small colonies; the nest is built among dense marshy vegetation, such as reed beds or at the top of trees, not necessarily near the water; many nests are built on one tree; twigs and reeds are used, the same elements over and over for many years, and as materials are added the nest becomes larger and more consolidated. Clutch size: up to 5 greenish pale blue eggs are laid; both parents share incubating and feeding duties.
Range: distribution of Nycticorax nycticorax obscurus ranges from Neuquén and south Río Negro to Tierra del Fuego; black specimens are more common on marine coasts; in Punta Norte, Península Valdés, in 1971 the authors sighted a group of over 15 individuals, all of them in the black phase; they also sighted them in Punta Tombo and Camarones; in the Andean region they are not as frequent but sightings have been recorded and the authors have collected specimens in Cholila and Gobernador Costa.
The race in the north of Argentina is Nycticorax nycticorax hoactli: overall very pale coloration except top of the head and back, which is similar to the southern race; in Patagonia the northern race reaches north of Río Negro and as far west as Cholila, in the province of Chubut, where specimens have been sighted and collected by the authors.
At Islas Malvinas Nycticorax nycticorax falklandicus is found, similar in coloration to Nycticorax nycticorax hoactli, but smaller in size. It also undergoes a black phase.
Illustrated Handbook of the Birds of Patagonia
Kindless: Kovacs Family
 
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Photographs: Mariano Diez Peña


Birding Patagonia • Birdwatcing in Bariloche, Patagonia, Argentina and Chile.
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Photographs on the website: Mariano Diez Peña