Description: It is a medium-sized and elegant heron, easily recognized by its upright posture and distinctive whistling call. The upperparts are mostly pale gray, while the neck, chest, and belly show a yellowish tone, a distinctive feature of the species. The chest also displays a well-defined grayish pectoral patch, which contrasts with the lighter coloration of the underparts. The head is relatively pale with a gray crown, and the bill is short and sturdy, usually grayish or yellowish with darker tones toward the tip. The legs are long and yellowish to greenish, adapted for slow walking across the ground or in shallow areas. In flight the neck is retracted, typical of herons, revealing broad silvery-gray wings. Its call is very distinctive and consists of sharp, piercing whistles, which inspired its scientific name.
Geographic distribution: It is widely distributed across South America, mainly occupying tropical and subtropical regions of the continent. Its range extends from central and southern Brazil to northern and central Argentina, including Paraguay, Bolivia, and Uruguay, with additional records in parts of Peru and Ecuador. In Argentina it is particularly frequent in the northeastern and central regions, though it may also occur in other open landscapes of the country. In most of its range the species is considered resident, although local movements or dispersal may occur in response to seasonal variations in food availability or environmental conditions.
Habitat: It prefers open landscapes with nearby water, such as wet grasslands, savannas, cattle pastures, marshes, and the edges of lagoons or streams. Unlike many herons that spend much of their time standing in water, this species is often observed walking across dry or slightly damp ground, especially in grasslands and open fields. It can also adapt to human-modified environments, including rural areas and agricultural landscapes, as long as open spaces and water sources are available. Its terrestrial foraging habits make it one of the more visible herons within the habitats it occupies.
Diet: Its diet consists mainly of invertebrates and small terrestrial vertebrates. It frequently feeds on relatively large insects such as grasshoppers, crickets, beetles, and larvae, which it captures while slowly walking and detecting the movement of prey. It may also consume frogs, lizards, small rodents, and occasionally fish or tadpoles, especially when foraging near water. The hunting strategy is deliberate and methodical: the bird advances slowly, pausing frequently before delivering a quick jab with the bill to seize its prey. In grazing areas it sometimes benefits from insects flushed by livestock.
Behavior: This species is generally solitary or seen in pairs, although small groups may occasionally gather where food resources are abundant. During the day it often walks slowly across open ground or perches on posts, fences, low trees, or rural structures from which it scans the surroundings. Its vocal behavior is particularly notable, producing clear, repeated whistles, especially during territorial interactions or in the breeding season. The flight is relatively slow and direct, with broad wingbeats, usually between feeding and resting areas within its territory.
Nesting: Breeding usually occurs during spring and summer, though timing varies across regions. The nest is typically placed in trees or shrubs near water or in open areas with good visibility. It consists of a platform made of sticks and plant stems, where the female usually lays between two and four pale eggs. Both adults take part in incubation and chick care. The parents defend the nesting area through calls and warning flights. Chicks remain in the nest for several weeks until they develop enough feathers and strength for their first flights.
Conservation status: Globally the species is classified as Least Concern, due to its broad distribution and generally stable populations. However, in some areas it may be affected by wetland loss, land-use changes, and the use of agrochemicals, which can reduce prey availability or alter nesting habitats. Despite these pressures, its ability to use pastures and rural landscapes has helped maintain its presence across much of its range.
Author of this compilation: EcoRegistros – 03/08/2026