[order] CICONIIFORMES | [family] Ardeidae | [latin] Syrigma sibilatrix | [authority] Temminck, 1824 | [UK] Whistling Heron | [FR] Heron flute-du-solei | [DE] Pfeifreiher | [ES] Garza chiflona | [NL] Fluitreiger
The Whistling Heron, Syrigma sibilatrix, is a medium-sized, often terrestrial heron of . There are two subspecies, the southern S. s. sibilatrix and the northern S. s. fostersmithi. Skeletal resemblances to the night herons 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.
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 herons 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.
Listen to the sound of Whistling Heron
Copyright remark: Most sounds derived from xeno-canto
South America : North, Southcentral, Southeast. The Whistling Heron is endemic to South America and is separated into two allopatric populations. The smaller lighter race occurs in the llanos grasslands of Venezuela and eastern Colombian and the larger, darker race is widely distributed in the grasslands of southeast South American from the Patanal of Paraguay southeast and to the coasts of southeast Brazil, Uruguay and northeast 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.
This species nests alone, unlike most herons, which nest in colonies. It may nest in mature trees such as araucarias 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, 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.
This species eats any small dryland and marsh animals it can catch. 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. It is probably less dependant on water for its food than any other heron
copyright: Mark Andrews
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend is not known, but the population is not believed to be decreasing sufficiently rapidly to approach the thresholds under the population trend criterion (>30% decline over ten years or three generations). The population size has not been quantified, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
The population is suspected to be stable in the absence of evidence for any declines or substantial threats
Sedentary; some local movements, connected with variations in local conditions. N populations may migrate, as absent from NE Venezuela Nov-Jan.