Chaco Owl

This medium-sized nocturnal bird of prey is characterized by its rounded silhouette and the complete absence of ear tufts on its head. It has a body length ranging from 33 to 38 centimeters, with an average weight between 340 and 450 grams, where females are slightly larger and heavier than males. The facial disc is highly conspicuous, colored pale grayish-white, bordered by a dark rim, and ornamented with concentric dark brown lines that converge toward eyes of a deep dark brown or blackish color, lacking a yellow iris. Its overall plumage presents a highly cryptic pattern; the upperparts exhibit a grayish-brown coloration densely barred with white, cinnamon, and dark brown, while the underparts are cream to whitish, crossed by highly defined and regular horizontal dark bars. Its wings are short and rounded, adapted for maneuvering through dense vegetation, and its tarsi and toes are covered with dense grayish feathers that muffle sound during flight and protect its extremities.

Geographical distribution It is strictly restricted and endemic to the Gran Chaco ecoregion in South America. Its range covers southern Bolivia (in the departments of Santa Cruz, Chuquisaca, and Tarija), western Paraguay (comprising the Boreal and Central Chaco region), and northern and central Argentina (extending through provinces such as Formosa, Chaco, Salta, Santiago del Estero, Tucumán, Catamarca, Córdoba, San Luis, and northern Santa Fe).

Habitat: It strictly inhabits the Dry Chaco biome, which is characterized by a semi-arid climate with a marked water seasonality. It prefers xerophytic deciduous forests, thorny shrublands, and dry savannas with the presence of mature trees. It is commonly found in forest formations dominated by white quebracho (Schinopsis lorentzii) and red quebracho (Schinopsis balansae), algarrobos (Prosopis spp.), mistol trees, cacti, and dense layers of thorny shrubs, avoiding excessively open areas or continuous humid forests.

Feeding It is an active predator with specialized carnivorous habits. Its diet is opportunistic and mainly consists of small mammals, with a strong preference for cricetid rodents, small marsupials, and bats. It also complements its diet by capturing small passerine birds, reptiles like lizards, some amphibians, and a significant amount of terrestrial arthropods, including large beetles, scorpions, and orthopterans. It hunts by ambushing from low perches, using its extraordinary two-dimensional hearing to locate prey on the ground before diving in a silent and precise flight.

Behavior: It has strictly nocturnal and crepuscular habits, remaining hidden during the day in the densest foliage of thorny trees or in natural cavities, where its plumage provides almost perfect camouflage against predators. It is a solitary and highly territorial bird that defends its home range through characteristic vocalizations. Its main call consists of a series of low, rhythmic, guttural hoots, emitted repetitively during dark nights, a deep sound that allows it to delimit its territory and communicate with its mate over long distances in the dense Chaco forest.

Nesting It is a monogamous species that establishes long-term pair bonds. The breeding process takes place during the southern hemisphere spring, taking advantage of the increase in available prey. It does not build its own nests; instead, it uses natural cavities in mature tree trunks or takes advantage of abandoned nests of larger birds of prey or large builders like the rufous hornero. The female lays a clutch of 2 to 3 pure white eggs of a rounded shape. Incubation is performed almost exclusively by the female for an estimated period of 28 to 30 days, during which time the male takes on the task of hunting and providing food for both her and the newly hatched chicks, which leave the nest after a few weeks of development.

Conservation status It is currently classified as Near Threatened (NT) under the International Union for Conservation of Nature (IUCN) Red List. Its main threat is the accelerated loss, fragmentation, and degradation of its natural habitat due to massive deforestation of the Chaco for the expansion of the agricultural frontier (mainly soy monocultures) and extensive cattle ranching, which drastically reduces the availability of optimal sites for the shelter and reproduction of this specialized raptor.