Whistling Heron
Encyclopedia
The Whistling Heron is a medium-sized, often terrestrial heron of South America
. There are two subspecies, the southern S. s. sibilatrix and the northern S. s. fostersmithi.
The overall impression of standing birds is gray, with flying birds showing conspicuous white rear parts (lower back, belly, and tail). In both subspecies, adults' upperparts except the lower back are blue-gray. The feathers of the sides of head, sides of the neck, breast, and scapular area are basically white but are stained gold to buff, perhaps by the powder down typical of heron
s or by secretions of the preen gland; the color varies from bird to bird. In the nominate subspecies, the crown and crest (separate plumes up to 4 cm long on the nape) are black and the upper wing coverts are cinnamon-colored; the crown and crest are slate-gray and the upper wing coverts are honey-colored (or "chamois") in fostersmithi. The bill is pink with blue to violet at the base and the distal third black, the legs are greenish and rather short, and there is a fairly big area of bare bluish skin around the eye.
Juveniles have the same overall pattern but are duller than adults, with the crown lighter, the breast light gray, and the throat and sides unstained white. Chicks are undescribed.
The bird is named for its most common call, a "loud, flute-like whistled kleeer-er" or "a high, reedy, complaining whistle, often doubled or uttered in a ser[ies], wueeee, wueeee,.…, easily imitated" or "a distinctive, characteristic, far-carrying, melodious whistle" that "can be rendered 'kee, kee, kee.'" It may also give "a slow, drawn-out whistle" when taking off. The alarm call is a harsh quah-h-h.
Unlike other herons, in flight it has fast, duck-like wingbeats and usually does not retract its neck fully.
The subspecies fostersmithi inhabits the Llanos
and the Orinoco
basin of Colombia
and Venezuela
. There are no breeding records "yet" from Colombia. The subspecies sibilatrix inhabits eastern Bolivia
, Paraguay
, western and southern Brazil
, Uruguay
, Chile
, and northeastern Argentina
. Recent records suggest that it may be expanding its range northward and eastward in Brazil
. It makes seasonal movements
at least in northeastern Venezuela, where it does not occur from November to January, but remains all year in other areas, such as Buenos Aires Province
, Argentina.
It occurs at altitudes up to 500 m (with a sight record from 2300 m) in seasonally flooded savanna
, often in drier grassy situations than other herons, but also in a wide variety of open waterlogged or shallowly submerged terrain. Because it roosts in trees, it particularly likes regions where open areas are mixed with woodlots. It has no objection to human-altered habitats such as pastures and roadsides, and it often perches on fenceposts.
Although patchily distributed, it is common in many areas, with no population considered vulnerable. It benefits from deforestation
and some agriculture
. As a successful heron of dry tropical country, it has been compared to two species originating in the Old World
: the Cattle Egret
and the Black-headed Heron
.
(as from an Aplomado Falcon
in one reported incident). It often holds still but also walks very slowly and may use more active techniques, even running after prey or catching flying insects (notably dragonflies
) from a standing position. It may allow humans to approach fairly closely rather than leave a good feeding spot. It typically feeds alone or in pairs, but is sometimes seen in groups up to 100, especially before roosting for the night.
This species nests alone, unlike most herons, which nest in colonies. It may nest in mature trees such as araucaria
s or exotic trees. One nest in Argentina was loosely built of sticks about 4m up in a eucalyptus
. The eggs are pale blue and speckled, about 4.7 × 3.6 cm, and the normal clutch is three or four. Incubation lasts about 28 days, and young fledge 42 days after hatching. Egg survival has been measured at 28% and nestling survival at 40%; storms that destroy nests are an important cause of losses. Based on observations of family groups, only two young normally fledge. Unlike most heron species, Whistling Herons care for young after leaving the nest; juveniles beg for food by hissing with their wings drooped.
s have led to a debate about whether the Whistling Heron is related to them, but since the 1980s it has been at least provisionally considered a relative of the genus Egretta
, with little doubt that it belongs in a genus of its own.
formerly used its neck plumes as trade items, though not so heavily as to reduce populations.
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
. There are two subspecies, the southern S. s. sibilatrix and the northern S. s. fostersmithi.
Description
The Whistling Heron measures 53 to 64 cm in length and weighs 521 to 546 g. The southern subspecies is bigger but has a shorter bill in proportion to the body.The overall impression of standing birds is gray, with flying birds showing conspicuous white rear parts (lower back, belly, and tail). In both subspecies, adults' upperparts except the lower back are blue-gray. The feathers of the sides of head, sides of the neck, breast, and scapular area are basically white but are stained gold to buff, perhaps by the powder down typical of heron
Heron
The herons are long-legged freshwater and coastal birds in the family Ardeidae. There are 64 recognised species in this family. Some are called "egrets" or "bitterns" instead of "heron"....
s or by secretions of the preen gland; the color varies from bird to bird. In the nominate subspecies, the crown and crest (separate plumes up to 4 cm long on the nape) are black and the upper wing coverts are cinnamon-colored; the crown and crest are slate-gray and the upper wing coverts are honey-colored (or "chamois") in fostersmithi. The bill is pink with blue to violet at the base and the distal third black, the legs are greenish and rather short, and there is a fairly big area of bare bluish skin around the eye.
Juveniles have the same overall pattern but are duller than adults, with the crown lighter, the breast light gray, and the throat and sides unstained white. Chicks are undescribed.
The bird is named for its most common call, a "loud, flute-like whistled kleeer-er" or "a high, reedy, complaining whistle, often doubled or uttered in a ser[ies], wueeee, wueeee,.…, easily imitated" or "a distinctive, characteristic, far-carrying, melodious whistle" that "can be rendered 'kee, kee, kee.'" It may also give "a slow, drawn-out whistle" when taking off. The alarm call is a harsh quah-h-h.
Unlike other herons, in flight it has fast, duck-like wingbeats and usually does not retract its neck fully.
Range and habitat
Llanos
The Llanos is a vast tropical grassland plain situated to the east of the Andes in Colombia and Venezuela, in northwestern South America. It is an ecoregion of the Flooded grasslands and savannas Biome....
and the Orinoco
Orinoco
The Orinoco is one of the longest rivers in South America at . Its drainage basin, sometimes called the Orinoquia, covers , with 76.3% of it in Venezuela and the remainder in Colombia...
basin of Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
and Venezuela
Venezuela
Venezuela , officially called the Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It borders Colombia to the west, Guyana to the east, and Brazil to the south...
. There are no breeding records "yet" from Colombia. The subspecies sibilatrix inhabits eastern Bolivia
Bolivia
Bolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...
, Paraguay
Paraguay
Paraguay , officially the Republic of Paraguay , is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to the east and northeast, and Bolivia to the northwest. Paraguay lies on both banks of the Paraguay River, which runs through the center of the...
, western and southern Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
, Uruguay
Uruguay
Uruguay ,officially the Oriental Republic of Uruguay,sometimes the Eastern Republic of Uruguay; ) is a country in the southeastern part of South America. It is home to some 3.5 million people, of whom 1.8 million live in the capital Montevideo and its metropolitan area...
, Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
, and northeastern Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
. Recent records suggest that it may be expanding its range northward and eastward in Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
. It makes seasonal movements
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
at least in northeastern Venezuela, where it does not occur from November to January, but remains all year in other areas, such as Buenos Aires Province
Buenos Aires Province
The Province of Buenos Aires is the largest and most populous province of Argentina. It takes the name from the city of Buenos Aires, which used to be the provincial capital until it was federalized in 1880...
, Argentina.
It occurs at altitudes up to 500 m (with a sight record from 2300 m) in seasonally flooded savanna
Savanna
A savanna, or savannah, is a grassland ecosystem characterized by the trees being sufficiently small or widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of C4 grasses.Some...
, often in drier grassy situations than other herons, but also in a wide variety of open waterlogged or shallowly submerged terrain. Because it roosts in trees, it particularly likes regions where open areas are mixed with woodlots. It has no objection to human-altered habitats such as pastures and roadsides, and it often perches on fenceposts.
Although patchily distributed, it is common in many areas, with no population considered vulnerable. It benefits from deforestation
Deforestation
Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use....
and some agriculture
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...
. As a successful heron of dry tropical country, it has been compared to two species originating in the Old World
Old World
The Old World consists of those parts of the world known to classical antiquity and the European Middle Ages. It is used in the context of, and contrast with, the "New World" ....
: the Cattle Egret
Cattle Egret
The Cattle Egret is a cosmopolitan species of heron found in the tropics, subtropics and warm temperate zones. It is the only member of the monotypic genus Bubulcus, although some authorities regard its two subspecies as full species, the Western Cattle Egret and the Eastern Cattle Egret...
and the Black-headed Heron
Black-headed Heron
The Black-headed Heron is a wading bird of the heron family Ardeidae, common throughout much of sub-Saharan Africa and Madagascar. It is mainly resident but some west African birds move further north in the rainy season....
.
Feeding
This species eats any small dryland and marsh animals it can catch, or even pirateKleptoparasitism
Kleptoparasitism or cleptoparasitism is a form of feeding in which one animal takes prey or other food from another that has caught, collected, or otherwise prepared the food, including stored food...
(as from an Aplomado Falcon
Aplomado Falcon
The Aplomado Falcon, Falco femoralis, is a medium-sized falcon of the Americas. The species' largest contiguous range is in South America, but not in the deep interior Amazon Basin. It was long known as Falco fusco-coerulescens or Falco fuscocaerulescens, but these names are now believed to refer...
in one reported incident). It often holds still but also walks very slowly and may use more active techniques, even running after prey or catching flying insects (notably dragonflies
Dragonfly
A dragonfly is a winged insect belonging to the order Odonata, the suborder Epiprocta or, in the strict sense, the infraorder Anisoptera . It is characterized by large multifaceted eyes, two pairs of strong transparent wings, and an elongated body...
) from a standing position. It may allow humans to approach fairly closely rather than leave a good feeding spot. It typically feeds alone or in pairs, but is sometimes seen in groups up to 100, especially before roosting for the night.
Reproduction
In a courtship display, the birds fly back and forth and glide in circles. A captive pair displayed by raising their plumes.This species nests alone, unlike most herons, which nest in colonies. It may nest in mature trees such as araucaria
Araucaria
Araucaria is a genus of evergreen coniferous trees in the family Araucariaceae. There are 19 extant species in the genus, with a highly disjunct distribution in New Caledonia , Norfolk Island, eastern Australia, New Guinea, Argentina, Chile, and southern Brazil.-Description:Araucaria are mainly...
s or exotic trees. One nest in Argentina was loosely built of sticks about 4m up in a eucalyptus
Eucalyptus
Eucalyptus is a diverse genus of flowering trees in the myrtle family, Myrtaceae. Members of the genus dominate the tree flora of Australia...
. The eggs are pale blue and speckled, about 4.7 × 3.6 cm, and the normal clutch is three or four. Incubation lasts about 28 days, and young fledge 42 days after hatching. Egg survival has been measured at 28% and nestling survival at 40%; storms that destroy nests are an important cause of losses. Based on observations of family groups, only two young normally fledge. Unlike most heron species, Whistling Herons care for young after leaving the nest; juveniles beg for food by hissing with their wings drooped.
Taxonomy
Skeletal resemblances to the night heronNight heron
The night herons are medium-sized herons in the genera Nycticorax, Nyctanassa and Gorsachius. The genus name Nycticorax derives from the Greek for “night raven” and refers to the largely nocturnal feeding habits of this group of birds, and the croaking crow-like call of the best known species, the...
s have led to a debate about whether the Whistling Heron is related to them, but since the 1980s it has been at least provisionally considered a relative of the genus Egretta
Egretta
Egretta is a genus of medium-sized herons, mostly breeding in warmer climates. Representatives of this family are found in most of the world, and the Little Egret, as well as being widespread throughout much of the Old World, has now started to colonise the Americas.These are typical egrets in...
, with little doubt that it belongs in a genus of its own.
Cultural significance
Indigenous peoplesIndigenous peoples of the Americas
The indigenous peoples of the Americas are the pre-Columbian inhabitants of North and South America, their descendants and other ethnic groups who are identified with those peoples. Indigenous peoples are known in Canada as Aboriginal peoples, and in the United States as Native Americans...
formerly used its neck plumes as trade items, though not so heavily as to reduce populations.