Bird O'clock

Discovering the Fascinating World of the Acre Antshrike: Plumages Behaviors and Conservation Efforts

The Acre Antshrike, or Thamnophilus divisorius, is a small bird found in the Amazon basin of South America. With its distinctive plumage and unique behavior, the species has become a fascination among birdwatchers and researchers alike.

In this article, we will explore the identification, plumages, and molts of this incredible bird.

Identification

The Acre Antshrike is a small bird, measuring around 13 centimeters in length, and weighing between 20-24 grams. It has a distinctive plumage, which makes it easily identifiable in the field.

Field

Identification

The male Acre Antshrike has a black head, back, wings, and tail, while its underparts are white with a gray wash. The female, on the other hand, has a brown back and wings, and her underparts are buffy white with a gray wash.

Both genders have a distinctive white spot behind their eyes, which is one of the most striking features of this species.

Similar Species

One of the birds that can be easily confused with the Acre Antshrike is the Amazonian Antshrike (Thamnophilus amazonicus). However, the Amazonian Antshrike has a longer bill, and its eye spot is less distinct than that of the Acre Antshrike.

Other species that have a similar plumage to the Acre Antshrike are the Dull-capped Antwren and the Magdalena Antbird. However, these species have different behaviors and are not typically found in the same areas as the Acre Antshrike.

Plumages

The Acre Antshrike has three plumages: juvenile, immature, and adult. The Juvenile plumage is mainly brown with buffy-white underparts.

The wings, back, and tail are a darker brown with white tips on the wing feathers. The Immature plumage is similar to that of the adult, but with a more muted plumage.

The male has a brownish-black head and back and a lighter brown tail. The female has a less distinct eye spot, lighter brown wings and tail, and buffy underparts with a gray wash.

The Adult plumage is the most distinctive. The Male has a black head, back, wings, and tail, and white underparts with a gray wash.

The female has a brown back and wings with gray wash, buffy-white underparts with a gray wash, and a less distinct eye spot.

Molts

The Acre Antshrike goes through two molts in a year – the prebasic molt and prealternate molt. The Prebasic molt happens after the breeding season, which is typically during December – February.

During this time, the birds will replace their feathers to prepare for the upcoming breeding season. The male bird will shed its black feathers, and the female bird will replace its browner feathers.

The Prealternate molt happens before the breeding season, which is typically during August – September. During this time, the birds will replace their feathers to look their best before the breeding season.

The male bird will grow back its black feathers but will have a muted plumage until the next breeding season. In conclusion, the Acre Antshrike is a unique species found in the Amazon of South America.

With its distinctive plumage, behavior, and molts, this bird has become a fascinating subject of research and birdwatching. Understanding the identification, plumages, and molts of this species can aid in its conservation by identifying populations in need of protection, and drawing attention to the beauty and importance of this bird.

Systematics History

The Acre Antshrike or Thamnophilus divisorius was first described by P. L.

Sclater and W. H.

Hudson in 1881. It belongs to the family Thamnophilidae, which is a large group of birds comprising about 240 species of antbirds found in the neotropics.

The Thamnophilidae family is divided into several subfamilies and tribes, with the Acre Antshrike belonging to the Thamnophilinae subfamily, within the genus Thamnophilus.

Geographic Variation

The Acre Antshrike has a wide distribution range, inhabiting a broad area in the Amazon basin of northwest Brazil, eastern Peru, and northern Bolivia. This species is known for its morphological variation across its range, which makes it difficult to identify the different subspecies.

Subspecies

Currently, there are six recognized subspecies of the Acre Antshrike. These subspecies vary in their morphology, distribution, and vocalizations.

The six subspecies are:

1. Thamnophilus divisorius divisorius: This is the nominate subspecies found in Acre, Brazil.

The male of this subspecies has a black head, back, wings, and tail, while the female has a brownish back and wings with a buffy-white underpart. 2.

Thamnophilus divisorius punctuliger: This subspecies is found in western Par, Amazonas, and Rondnia, Brazil. It is similar to Thamnophilus divisorius divisorius, but the male has a denser spotting on the underparts, and the female has a more distinct gray wash on its underparts.

3. Thamnophilus divisorius roraimae: This subspecies is found in Guyana and Venezuela.

It is larger than Thamnophilus divisorius divisorius, and the male has brighter, more contrasted black and white plumage. 4.

Thamnophilus divisorius guianensis: This subspecies is found in French Guiana, Surinam, and eastern Guyana. The male has a more extensive black head, and the female has a more extensive gray wash on the underparts.

5. Thamnophilus divisorius iheringi: This subspecies is found in eastern Peru, northeast Bolivia, and Mato Grosso, Brazil.

The male has a more extensive black on the head and back, and the female has a less distinct eye spot. 6.

Thamnophilus divisorius hypostictus: This subspecies is found in northeastern Brazil. The male has a denser spotting on the underparts, and the female has a more extensive gray wash than other subspecies.

Related Species

The Acre Antshrike is part of the Thamnophilus genus, which includes over 30 species of antshrikes found in the neotropics. They are small, often skulking birds that are usually found in forest understory or scrubby habitats.

Some of the related species to the Acre Antshrike include:

1. Thamnophilus aethiops: A widespread species found throughout the Amazon basin.

2. Thamnophilus stictocephalus: A species found in northern South America, including Colombia and Venezuela.

3. Thamnophilus palliatus: A species found in eastern Brazil.

4. Thamnophilus schistaceus: A species found in northeastern Brazil.

Historical Changes to Distribution

The distribution of the Acre Antshrike has undergone changes over time due to habitat loss and fragmentation. The Amazon basin has experienced significant deforestation in the past several decades, which has led to the loss of large areas of habitat for many bird species, including the Acre Antshrike.

In addition to habitat loss, the Acre Antshrike is also threatened by the pet trade and hunting. The bird’s distinctive plumage and behavior make them a popular target for bird collectors and hunters.

Conservation efforts are in place to help protect the Acre Antshrike and its habitat. Several protected areas have been established within the bird’s range, including the Serra do Divisor National Park in Brazil and the Manu National Park in Peru.

These efforts aim to reduce habitat loss and fragmentation, which will benefit not only the Acre Antshrike but also other species that share the same habitat. In conclusion, the Acre Antshrike is a fascinating and unique bird species that has undergone changes in distribution over time.

Its geographic variation, subspecies, and related species make it a subject of study and fascination for ornithologists and bird lovers alike. Ongoing conservation efforts are critical to ensure the survival of this species and its habitat in the face of habitat loss and fragmentation.

Habitat

The Acre Antshrike inhabits the Amazon basin of South America, where it occupies various types of forest and scrub habitats. It prefers dense understory and forest edges with abundant shrubs and small trees, often near streams and swampy areas.

The Acre Antshrike has also been observed in secondary growth forest and areas with selective logging. Although it is mainly found in lowland areas, the species has been recorded at elevations of up to 1500 meters above sea level.

Movements and Migration

The Acre Antshrike is largely non-migratory, and most of its movements are related to territoriality and breeding. During the breeding season, males defend their territories against other males by singing and engaging in aggressive behavior.

These behaviors are accompanied by foraging and moving around within their territories, but they remain in their territories for most of the breeding season. However, juveniles and immature Acre Antshrikes may disperse from their natal territories after the breeding season.

These movements are still poorly understood, and the extent to which they disperse is still unknown. Some studies have suggested that they may move only short distances, while others have found evidence of long-distance movements.

The Acre Antshrike is not known to undertake long migrations, and its range is confined to the South American continent. However, the species may be subject to local movements due to changing environmental conditions or food availability.

For example, during the dry season, some areas become more favorable for foraging, and the birds may move to these areas to take advantage of the conditions.

Threats

The Acre Antshrike is threatened by habitat loss and fragmentation due to human activities such as logging, mining, and agriculture. These activities frequently involve the clearing of large areas of forest, which results in the loss of habitat and fragmentation of the remaining forest.

This fragmentation can lead to genetic isolation and inbreeding, which can be detrimental to the long-term survival of the species. The Acre Antshrike is also threatened by the pet trade and hunting.

The bird’s distinctive plumage and behavior make them a popular target for bird collectors and hunters, which can lead to population declines. Furthermore, because the Acre Antshrike is a slow-moving species that is usually found in low dense understory, it is particularly vulnerable to capture by hunters.

Conservation

Efforts to protect the Acre Antshrike and its habitat are critical to ensure the species’ survival. Several protected areas have been established within the bird’s range, including the Serra do Divisor National Park in Brazil and the Manu National Park in Peru.

These protected areas aim to reduce habitat loss and fragmentation, which will benefit not only the Acre Antshrike but also other species that share the same habitat. Furthermore, collaboration between government agencies, conservation organizations, and local communities is necessary to ensure that these protected areas are well managed and enforced.

Effective management can ensure that the Acre Antshrike and other species receive the protection they need in their natural habitats, promoting the long-term survival of the species. Public education and awareness campaigns can also help to reduce the threat of the pet trade and hunting.

By highlighting the importance of protecting the Acre Antshrike and other endangered species, these campaigns can raise awareness among local communities and tourists, reducing the demand for these animals as pets and the pressure on wild populations.

Conclusion

The Acre Antshrike is a small bird species found in the Amazon basin of South America. The bird inhabits various types of forests and scrub habitats and is largely non-migratory, with movements related to breeding and territoriality.

The species is threatened by habitat loss, fragmentation, and hunting, making conservation efforts critical for its survival. By protecting the Acre Antshrike’s habitat and raising public awareness about its conservation needs, we can ensure the long-term survival of this fascinating and unique bird species.

Diet and Foraging

Feeding

The Acre Antshrike is an insectivorous bird, meaning that it relies on insects as its primary food source. Additionally, it has a specialized foraging behavior that differs from other species of birds.

Instead of following swarms of army ants, which is a typical strategy for many antbirds, the Acre Antshrike forages in the understory bushes, relying on the ants’ cleaning process to uncover its prey.

Diet

The Acre Antshrike feeds on a variety of insects, including beetles, grasshoppers, and spiders. It has also been observed eating small lizards and frogs.

By foraging along with the ants, the bird has access to a wider range of prey species than it would have otherwise, allowing it to maximize its foraging efficiency.

Metabolism and Temperature Regulation

Due to its unique foraging behavior, the Acre Antshrike has a relatively low metabolism compared to other bird species. This is because it can cover a large area without expending too much energy by foraging in a stationary position.

Additionally, this bird has a good sense of thermoregulation, being able to maintain body temperature adequately.

Sounds and Vocal Behavior

Vocalization

Like many birds, the Acre Antshrike is known for its unique vocalizations, which play an essential role in communication, breeding, and territorial behavior. The male and female of the species have different vocalizations, with the female being less vocal than the male.

The male Acre Antshrike has a characteristic and recognizable song, which is usually delivered from a concealed location within the bush or understory. The song is a series of clear and liquid whistles, with each note increasing in pitch before descending again.

The female Acre Antshrike has a similar but more subdued call than the male. She produces a short, series of sharp notes, used primarily for communication with her mate during breeding or for mutual recognition while foraging in their territories.

Vocalizations play a vital role in a complex communication system for this species. In addition to proper song and call, aggressive vocalizations like growls and hissing sounds are used to defend territory against intruders.

Because vocalizations are so important for communication and territorial defense, understanding these sounds can aid in studies of the Acre Antshrike’s behavior and ecology. Vocalization studies may help to identify different populations, understand their habitat preferences, and inform conservation efforts to focus on critical areas to preserve habitats.

In conclusion, the Acre Antshrike has a specialized foraging strategy that is different from other bird species due to its reliance on ants’ cleaning process to uncover prey. By foraging in the understory, the bird can access a wide variety of insect species.

Like many other birds, the species relies on vocalizations to communicate with mates, defend territories and forage in groups, indicating the importance of protecting this bird habitat.

Behavior

Locomotion

The Acre Antshrike is primarily a ground-dwelling bird that forages on or near the forest floor, using its specialized foraging behavior to access prey. The bird is not well-suited for flight and prefers to move by hopping and running across the forest floor.

When threatened, the Acre Antshrike will often run or hop away, relying on its camouflage to avoid detection.

Self Maintenance

Like many bird species, the Acre Antshrike spends a significant amount of time grooming and maintaining its plumage. This not only helps to keep its feathers clean and in good condition but also helps to maintain its insulation and thermoregulation capabilities, crucial for a bird that spends most of its time on the forest floor.

Agonistic Behavior

The Acre Antshrike is a territorial bird that will aggressively defend its territory from other birds of the same species. Males will engage in aggressive vocalizations, such as growls and hisses, to defend territory against intruders.

Additionally, males will use physical displays such as wing threats or displays of the black plumage to intimidate other males and defend their territory.

Sexual Behavior

During the breeding season, the Acre Antshrike engages in complex sexual behavior. Males will establish territories and court females using a series of complex displays that include wing-waving, bowing, and singing.

Once courtship is successful, the pair will build a nest and engage in mating behavior.

Breeding

The breeding season for the Acre Antshrike is during the wet season, which occurs between November and April. During this time, males establish territories and begin courtship displays to attract females.

The courtship display involves the male performing a series of complex visual and auditory displays, such as wing-waving, bowing, and singing. The male will also bring food to the female, which is an important part of the courtship process.

Once a pair is formed, they will build a nest together. The nest is constructed by weaving together twigs, grasses, and other plant materials.

The female will lay two or three eggs, which are incubated by both parents. The eggs will hatch after 16-18 days, and the parents will continue to care for the young until they are ready to leave the nest.

Demography and Populations

The Acre Antshrike has a relatively large distribution range, and its populations

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