Fr: Onoré zigzag – Butor zigzag
Ang: Zigzag Heron
All: Zickzackreiher
Esp: Avetigre Enana
Ita: Tarabusino zebrato
Nd: Zigzagreiger
Sd: Zebrahäger
Port (Brazil): Socoí-zigue-zague

Photographers:

Roger Ahlman
Pbase Galleries Peru and Ecuador & My bird pictures on IBC

Jean-Claude Billonneau
Photo gallery of BILLONNEAU Jean-Claude

Text by Nicole Bouglouan

Sources :

HANDBOOK OF THE BIRDS OF THE WORLD vol 1 by Josep del Hoyo-Andrew Elliot-Jordi Sargatal - Lynx Edicions - ISBN: 8487334105

A GUIDE TO THE BIRDS OF COLOMBIA by Steven L. Hilty and William L. Brown - Princeton University Press – ISBN 069108372X

Avibase (Lepage Denis)

BirdLife International (BirdLife International)

SORA Searchable Ornithological Research Archive (Blair O. Wolf)

SORA - Wilson Bull., 103(4), 1991, pp. 661-664
The voice and first nesting records of the Zigzag Heron in Ecuador

Heron Conservation - The IUCN-SSC Heron Specialist Group

AVIBIRDS.COM
OBSERVATIONS OF THE BEHAVIOR OF THE ZIGZAG HERON
WILLIAM E. DAVIS, JR. - PAUL K. DONAHUE AND ELEANOR G. PERKINS

Arthur Grosset's Birds (Arthur Grosset)

PLANETOFBIRDS.COM

Wikipedia, the free encyclopaedia

HBW Alive

 

Home page

Page Ardeidae Family

Summary cards

 

Zigzag Heron
Zebrilus undulatus

Pelecaniformes Order – Ardeidae Family

INTRODUCTION:
The Zigzag Heron is included in the monotypic genus Zebrilus within the family Ardeidae. This species is threatened by heavy deforestation in the Amazon Basin and illegal hunting in Venezuela.
This small heron is secretive and little known as it usually frequents the dense tropical forests. It forages in wet areas and along the shores of marshes, lakes, pools and slow-moving rivers, usually at dawn and dusk.
The Zigzag Heron is currently related to tiger-herons and bitterns. But it has several morphological features and behaviour closely related to bitterns, and recent molecular studies support this hypothesis.

DESCRIPTION OF THE BIRD:
Biometrics:
Length: 30-33 cm
Weight: 120-125 gr

The adult is a small heron with dark, vermiculated plumage. Back and upperwing are brown and blackish, with buff-white bars and speckles. Flight feathers and rectrices are dusky and unbarred.
The underparts are paler, mostly creamy-buff with blackish bars, speckles and streaks, especially on foreneck and breast, whereas belly and vent are much paler with less markings.

Head and neck are finely mottled grey, with bushy occipital black crest forming a conspicuous mane when erect.
The blackish bill is relatively short. It may have paler lower mandible, horn or yellowish. The eyes are pale yellow. Lores are blackish. The legs are greyish-horn to yellowish-green and the toes are mostly yellow.

Both adults are almost similar, but the male may have more heavily marked underparts.
The juvenile is mostly rufous on upperparts, face and neck. The underparts are tawny with weak dark barring. Bill and legs are greenish-yellow.

RANGE:
The Zigzag Heron is found in the entire Amazon Basin E of the Andes, in Colombia, Venezuela, Ecuador, Peru, Bolivia, Brazil, French Guiana, Guyana and Suriname.

HABITAT:
The Zigzag Heron frequents swamps, grassy borders of small pools, slow-moving forested rivers, lakes and marshes inside the dense tropical forests, gallery forest in savannas and llanos habitats.  

CALLS AND SONGS: SOUNDS BY XENO-CANTO           
The Zigzag Heron gives “oooop” calls described as a hollow hooting. This call can be given alone or in series of 7-8 calls. Another call is a nasal, higher-pitched, single “ahnnn”. A third call combining the first two sounds is given in series. The hooting call is that of adults, whereas the “ahnnn” call is mostly that of the juveniles.
While giving these calls, the bird holds the bill slightly upwards and semi-open. The skin of the throat is moving while the sound is produced.
These calls are far-carrying, characteristic of forest bird species, and typically given at dawn and dusk.

The female lays 1-2, usually only one pure white egg. The duration of the incubation is unknown, but both sexes share this period. In the small bitterns, this period lasts about 14-20 days.
At hatching, the downy chick is yellowish-cream or white, and gains gradually the rufous immature plumage. The darker feathers of head, wings and back appear last. Bill and legs are yellowish-green. The eyes are yellow. As the young is growing, it climbs into the branches around the nest. The nesting time ranges from 25-30 days in small bitterns. Both adults feed and tend the young.

PROTECTION / THREATS / STATUS:
The Zigzag Heron is threatened by habitat loss due to heavy deforestation in the Amazon Basin for cattle and agriculture expansion. This species is rare and local, secretive and elusive, making difficult to find the birds and to estimate the size of their populations.
The Zigzag Heron is present in several conservation units and protected areas, but the illegal hunting is still a problem in Venezuela.
This specie sis currently classified as Near Threatened.

BEHAVIOUR IN THE WILD:
The Zigzag Heron often hunts by standing on perch, tree or log, above the water, usually with the neck retracted. Once the prey is detected, it wags the tail back and forth, the body is held almost horizontally and the neck is extended prior to catch the prey.
Like numerous Ardeidae, it also hunts by standing motionless in shallow water, or by walking slowly along the shores. However, the preys are mainly caught by pecking instead of stabbing.
It feeds on fish and insects, including flying ones. Flying insects are caught by “standing flycatching”. The heron performs the typical “stand and wait” behaviour and catches flying insects. It usually feeds at dawn and dusk.

The courtship behaviour of the Zigzag Heron is currently unknown. This species nests solitary or close to other species such as Tigrisoma lineatum. Copulation was observed in April. There are probably more than one brood per year. Both parents share all the nesting duties.

The Zigzag Heron is probably resident in its range, with some local movements related to food resources and water levels.
This species flies in an indirect weaving fashion or zig zag, giving the bird its name.

REPRODUCTION OF THIS SPECIES:
The breeding season takes place between April and July in W of the range, but it varies depending on the region, mostly December/March in Brazil.
The Zigzag Heron often nests solitary and sometimes close to other Ardeidae.  
The nest is a shallow loose platform made with twigs and thorny branches along the periphery. This structure is built between 1 and 3 metres above ground or water, in trees or bushes on the shore or overhanging water. From an observation, some nests were placed within a patch of extremely thorny Bactris gasipaes fronds that were woven into the edge of the nest. Some nests are flooded if the water level rises suddenly.