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8 Fascinating Facts about the Bolivian Slaty-Antshrike

If you’re a bird enthusiast looking for new species to observe and learn about, look no further than the Bolivian Slaty-Antshrike. This unique bird is a common sight in the forests of Bolivia and is a fascinating subject for ornithologists and casual birdwatchers alike.

In this article, we’ll delve into the identification, plumages, molts, and similar species of the Bolivian Slaty-Antshrike.


Identifying the Bolivian Slaty-Antshrike can be a bit tricky for those unfamiliar with the species. However, several key features can help you differentiate it from other birds.

This bird species has a sleek, slate-gray body with a black hood that extends to the back of its neck. It also has a distinctive white collar, which is most visible in mature adults.

The males and females are similar in appearance, but males tend to have a slightly darker hood, while females have a browner or grayer appearance overall. Field


While the Bolivian Slaty-Antshrike can be challenging to identify in the field, there are a few cues that can help you distinguish it from other birds.

This species is relatively small, measuring around six inches in length, and has a short, stout bill. It is also a skilled climber, frequently perching on branches and trunks of trees in search of insects and other prey.

When vocalizing, its call is a sharp, high-pitched whistle that can be heard from a distance.

Similar Species

One of the most significant challenges in identifying the Bolivian Slaty-Antshrike is its resemblance to other antshrike species. Species such as the Fasciated Antshrike and the Plain Antvireo have similar body types and colors.

It is crucial to observe distinct features of the Bolivian Slaty-Antshrike, such as its white collar, to distinguish it from other species.


The Bolivian Slaty-Antshrike has several plumages during its lifetime, which vary depending on age, sex, and breeding status. Juvenile birds differ from adults in that they have a mottled gray and brown appearance with speckled undersides.

Immature males resemble females but lack the characteristic black hood and have a lighter-colored white collar. Mature males attain their distinctive black hood and retain a darker, permanent plumage.

Females mature to a brown-gray color with the white collar remaining prominent.


Like other bird species, the Bolivian Slaty-Antshrike undergoes molts throughout its lifetime. Molting refers to the process of shedding old feathers and regrowing new ones.

This process usually occurs once or twice each year, with the replacement of feathers occurring gradually over several weeks or months. During molting, you may observe temporary patches of gray or brown feathers on juvenile or immature birds.


The Bolivian Slaty-Antshrike is a unique and fascinating bird species that offers bird enthusiasts the opportunity to observe, study, and appreciate its unique features. With its distinctive appearance, climbing abilities, and vocalizations, this bird is a fascinating subject for birdwatchers and scientists alike.

By understanding its various plumages and molts, you can gain a deeper understanding of this bird species and the importance of conservation efforts to sustain its population.

Systematics History

The Bolivian Slaty-Antshrike (Thamnophilus sticturus) belongs to the family Thamnophilidae, which comprises over 240 species of birds commonly known as antbirds. The antbird family is known for its insectivorous diet and diverse plumages, with many species exhibiting sexual and geographic dimorphism.

While the Bolivian Slaty-Antshrike is a relatively well-known bird in South America, its systematics history remains poorly understood.

Geographic Variation

Geographic variation refers to the differences in physical characteristics of a species from one geographic area to another. The Bolivian Slaty-Antshrike exhibits a marked geographic variation in its plumage across its range, which spans from eastern Bolivia to central Brazil and northern Argentina.

The subspecies from Bolivia and western Brazil (Thamnophilus sticturus bolivianus) have a darker plumage, while the subspecies from eastern Brazil and northeastern Argentina (T. s.

ochraceiventris) have a lighter-colored plumage. The latter subspecies is also larger in size, measuring up to 8 inches in length compared to the 6.7 inches of the Bolivian subspecies.


The Bolivian Slaty-Antshrike was initially described as its own species in 1818 by Johann Baptist von Spix, a German naturalist. However, it was later classified under the genus Drymophila, a grouping of New World antbirds.

It wasn’t until 1867 that the Bolivian Slaty-Antshrike was again reclassified, this time under the genus Thamnophilus.

Currently, two subspecies of the Bolivian Slaty-Antshrike are recognized: T.

s. bolivianus and T.

s. ochraceiventris.

T. s.

bolivianus is found in Bolivia, western Brazil, and Paraguay, while T. s.

ochraceiventris is found in eastern and central Brazil and northeastern Argentina. The two subspecies differ in their plumage and size, as discussed above.

Related Species

The Bolivian Slaty-Antshrike is part of a complex of several other Thamnophilus species that are morphologically similar. These include the Stripe-backed Antshrike (T.

melanothorax), the Planalto Slaty-Antshrike (T. pelzelni), and the Rio de Janeiro Antbird (Cercomacra brasiliana).

These species share similar physical characteristics, such as the dark hood and slate-gray body, making them particularly difficult to distinguish in the field. Genetic studies are increasingly being used to resolve the taxonomic status of these similar species in the Thamnophilus genus.

Historical Changes to Distribution

The Bolivian Slaty-Antshrike’s distributional range has undergone multiple changes throughout history. One of the main drivers of these changes is the fragmentation of forests, particularly in the Chaco and Cerrado biomes in South America.

Deforestation has resulted in the fragmentation and isolation of populations of Bolivian Slaty-Antshrikes, which has contributed to the loss of genetic diversity and the potential for increased inbreeding. Another factor influencing the distribution and abundance of Bolivian Slaty-Antshrikes is climate change.

The loss of habitat related to climate change, such as the prolonged or recurring droughts that impact the Cerrado biome, exacerbate the effects of deforestation on bird populations and further restrict their range. Finally, the Bolivian Slaty-Antshrike’s distribution has also been affected by hunting and trapping for the pet trade, particularly in Bolivia.

Although this practice is illegal, it remains a significant threat to many species of birds in the region, including the Bolivian Slaty-Antshrike.


The Bolivian Slaty-Antshrike has undergone a variety of shifts in geographic distribution, related to factors such as deforestation, climate change, and human intervention. The current subspecific classification of the Bolivian Slaty-Antshrike is based on morphological characteristics, but ongoing genetic research may provide additional insights into the historical diversification and geographic variation of the species.

This bird’s population remains threatened by ongoing human activities, and conservation efforts are essential to prevent its range from further shrinking.


The Bolivian Slaty-Antshrike is an obligate top of understory bird that prefers habitats near rivers and streams, including gallery forests, humid forests, and riparian vegetation. It is commonly found in areas with dense vegetation providing cover and food.

This bird often shelters near the bases of trees or shrubs and moves through the understory of the forest, searching for prey. The species is distributed throughout various forest types, including native and secondary growth, and is especially common in the ecotone areas between forested habitats and open savannas.

It is a less frequent visitor of more mature and larger forests. In Bolivia, the bird’s habitat includes savannas, grasslands, and forested areas near rivers, with an average elevation range from 200 to 2000 meters above sea level.

Movements and Migration

The Bolivian Slaty-Antshrike is a non-migratory bird, meaning that it does not undertake seasonal movements, including those related to breeding. However, it is known to make altitudinal migrations in response to shifts in environmental and food availability.

During periods of drought in the Cerrado biome, the species descends to lower elevations, preferring to feed in forested areas near rivers during the dry season. While the Bolivian Slaty-Antshrike is a relatively sedentary species, it may undertake irregular movements related to food availability.

These movements may result in some individuals being found outside their typical range or habitat. For example, some individuals have been spotted around cleared or disturbed areas where they may move to find more food.

The movements of Bolivian Slaty-Antshrikes can also be influenced by human activities, such as logging, clearing land for agriculture, or constructing dams and roads. With forest fragmentation, individuals may become isolated in small forest fragments, leading to local population declines or even extinction.

Conservation Implications

The Bolivian Slaty-Antshrike is currently listed as a species of Least Concern by the International Union for Conservation of Nature (IUCN). However, the bird remains under threat from habitat loss due to deforestation and fires, unsustainable logging practices, and nest predation from invasive species such as the Common Marmoset (Callithrix jacchus).

The maintenance of gallery forests, along the river system, is crucial to the species. Furthermore, habitat connectivity and the protection of primary forests are essential components of conservation strategies for this and other bird species.

Restoring degraded habitats, reforesting or regenerating abandoned pastures, and maintaining corridors between forests areas are important methods to promote the persistence of this bird and other fauna in the region. As with any bird species, the protection of the Bolivian Slaty-Antshrike requires a visually guided conservation approach.

It includes monitoring of populations, investigating the bird’s movements and responses to particular biotic and abiotic environmental changes. Also, the engagement of local communities, native and traditional knowledge from the Amazonian areas can help conservation proposals for this bird in particular, as well as to support biodiversity conservation initiatives.


As many other species in their family, the Bolivian Slaty-Antshrike relies heavily on habitat availability, quality, and connectivity. Although it is non-migratory, it may undertake altitudinal migrations to follow the distribution of its preferred foods.

Human-mediated threats associated with forest fragmentation, habitat loss, and land-use management, among other factors, stress this bird’s populations. Further studies exploring genetic diversity, geographical variation, and molecular evolution of the Bolivian Slaty-Antshrike can support conservation efforts to preserve and manage these species in its natural environment.

Diet and Foraging


The Bolivian Slaty-Antshrike is an expert climber equipped with strong beaks and sharp claws that it uses to capture insects and other small prey hiding within bark crevices or tree crowns. Foraging behavior includes acrobatic climbing, hopping, and prolonged bouts of searching or peering.

The individuals typically forage in pairs, and sometimes in small groups of up to four individuals during the breeding season. It forages mainly in the subcanopy of the forest, but when feeding after periods of drought, this species can also be seen foraging in the understory.

Bolivian Slaty-Antshrikes will search the bark of trees, twigs, and leaves for insects, spiders, caterpillars, moths, and other invertebrates and occasionally small lizards.


The Bolivian Slaty-Antshrike is an insectivore that feeds mainly on arthropods. The insect prey commonly consumed by the species include katydids, locusts, beetles, and Hymenoptera such as ants, bees, and wasps.

Bolivian Slaty-Antshrikes are known to peck through shredded bark, often looking for insects and their larvae. The preferred insects in the diet may probably depend on the bird’s geographic location and habitat.

Metabolism and Temperature Regulation

The Bolivian Slaty-Antshrike has a high metabolism, which is reflected in its foraging behavior. The bird’s metabolic rate increases during periods of high activity, such as when foraging for prey or when threatened by predators, such as the Black Caracara (Daptrius ater).

To maintain its body at optimal temperature, it uses thermoregulation, which involves adjusting its metabolic rate to changing environmental conditions. The bird maintains its body temperature using panting, especially during hotter periods.

Sounds and Vocal Behavior


The Bolivian Slaty-Antshrike is a vocal bird that produces a range of calls, whistles, and songs, which it uses to communicate with other members of their species and to defend its territory. The Bolivian Slaty-Antshrike’s vocalizations are sharp, high-pitched whistles that are easy to distinguish from other bird species in the area, mainly when the bird feels disturbed.

These sounds are usually consistent with the bird’s territorial behavior, warning other birds, and trying to maintain a protected area.

During the breeding season, female and male individuals participate in the pair’s duet.

The pair produces vocalizations simultaneously, alternating between short and long notes, often with the male taking the lead melody. This type of vocalization is a reliable indication of a pair’s breeding status.


Overall, the Bolivian Slaty-Antshrike is a fascinating species that is specially adapted to its forest habitat and uses a range of behaviors and vocalizations to survive and thrive. The bird’s expert climbing skills and distinctive vocalizations are indicative of its evolution and adaptation to the forest’s understory.

The dependence on forest habitats and sensitivity to human-mediated disturbances make the Bolivian Slaty-Antshrike a vulnerable species. Understanding this bird’s feeding habits, vocal behavior, and metabolism provides a foundation for conservation and management strategies that aim to protect the bird and its habitat.



As previously mentioned, the Bolivian Slaty-Antshrike is an expert climber that moves acrobatically through the forest canopy. The bird often bounces and hops along the branches of trees and shrubs in search of prey, while also exploring the bark crevices and leaf litter for insects.

It also frequently flycatches, jumping from visible perches to catch aerial insects in mid-air.


Like many bird species, the Bolivian Slaty-Antshrike dedicates a substantial portion of its time to self-maintenance. It spreads its wings and tail feathers to expose its skin, allowing it to regulate its body temperature and preen its feathers to remove parasites such as ticks and lice.

Agonistic Behavior

The Bolivian Slaty-Antshrike exhibits a range of agonistic behaviors related to territorial defense and competition for resources. Males often engage in aerial chases and other forms of aggressive behavior to drive away competing males and maintain their territory.

The bird also exhibits threat displays such as raising its crest, vocalizations, and defensive postures such as lowering its head while raising its wings.

Sexual Behavior

During the breeding season, males and females pair up and engage in courtship behaviors, including displays of affection, gift-giving, and courtship feeding. The pairs lay clutches of two or three eggs in an elaborately woven nest.

Females typically incubate the eggs, while males feed and defend the nest.


The Bolivian Slaty-Antshrike breeds during the rainy season, which runs from November to February in Bolivia. The nesting process is a collaborative effort between the male and female, who work together to construct a cup-shaped nest made from twigs, leaves, fibers, and other plant material.

The nest is located in dense shrubs, trees, or thickets, and is woven together with spider webs to reinforce the structure.

The female lays a clutch of two or three eggs, which are incubated for around 16 days.

While the female incubates the eggs, the male provides food and defends the nest from intruders. The chicks hatch after about two weeks of incubation and are fed by both parents until they fledge, usually when they are around 16-18 days old.

Demography and Populations

The Bolivian Slaty-Antshrike remains widespread and relatively common throughout its range. However, the overall population size has been declining due to deforestation and habitat fragmentation, amongst other human-mediated threats.

Moreover, the species has known distribution gaps that

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