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The Marvelous Black Jacobin: A Fascinating Look Into Its Evolution Habitat and Behavior

The Black Jacobin, scientifically known as Florisuga fusca, is a stunning bird species that belongs to the hummingbird family. It is endemic to Brazil and found mainly in the Atlantic Forest, a diverse and endangered ecosystem.

This article aims to provide information on the identification, characteristics, and molts of the Black Jacobin.


Field Identification

The Black Jacobin is a medium-sized bird species that measures approximately 12 centimeters. It has distinctive black plumage with a metallic green sheen on its back and a blue-violet spot on its throat.

The bill is long, straight, and black, while its legs and feet are dark brown.

Similar Species

The male Black Jacobin closely resembles the Violet-capped Woodnymph and the Swallow-tailed Hummingbird. To distinguish them, observe the head size, tail, and wing markings.

The Violet-capped Woodnymph has a larger head, a distinctive violet cap on the head, a slightly longer tail, and white spot on the wings. On the other hand, the Swallow-tailed Hummingbird is larger in size with a more extended tail and a white stripe on its dark blue-black belly.


The Black Jacobin has a typical hummingbird plumage that can be broadly divided into two categories; adult male and female plumages. The male has distinctive black feathers, a green sheen, and a blue-violet spot on the throat.

Meanwhile, the females have brown, copper, and green feathers on their backs, with a relatively duller throat spot.


The Black Jacobin undergoes a pre-basic molt at the start of the breeding season in autumn. The males replace the central flight feathers and the rectrices while maintaining the rest of the plumage.

In contrast, the females replace all their feathers, retaining only the wings and tail feathers. The Black Jacobin is one of the most stunning bird species in the Atlantic Forest, thanks to its unique features and adaptations.

While it is easy to identify in the field, it is essential to differentiate it from similar species. Its molts are also fascinating, providing further insight into their life cycle and breeding behavior.

In conclusion, the Black Jacobin is a unique bird species that needs conservation efforts to prevent its decline. This article provided valuable information on its identification, plumages, and molts, highlighting its contributions to biodiversity in the Atlantic Forest.

Systematics History

The Black Jacobin, Florisuga fusca, was first described by Johann Baptist von Spix in 1824. Initially, it was classified as Trochilus fusca, but its current taxonomical classification is based on molecular and morphological evidence.

The molecular DNA analyses showed that the Black Jacobin is genetically closer to the Andean Emerald (Agyrtria franciae) than the other Brazilian hummingbirds. Furthermore, its morphological features distinguish it from other hummingbirds, and it was placed into the Florisuga genus.

Geographic Variation

The Black Jacobin exhibits significant variation in its geographic range. The subspecies of Black Jacobin occupying the Atlantic Forest of Brazil is darker and has more iridescent feathers compared to the subspecies that inhabit the rest of its range.

In contrast, the subspecies found in the Amazon Basin and the Guianas have duller feathers and a more bronzy sheen on their backs.


Currently, three subspecies of the Black Jacobin are recognized. They are the nominate subspecies, Florisuga fusca fusca, Florisuga fusca mercurius, and Florisuga fusca fuscus.

The nominate subspecies, Florisuga fusca fusca, is located in the Atlantic forest of southeast Brazil. Florisuga fusca fuscus is present in northeast Brazil, French Guiana, Suriname, and Guyana, while Florisuga fusca mercurius is restricted to the Amazon Basin of Brazil, Venezuela, Colombia, and Ecuador.

Related Species

The Black Jacobin is a member of the Trochilidae family, commonly known as hummingbirds. Within the hummingbird family, it belongs to the subfamily Trochilinae, which has over 100 genera consisting of around 400 hummingbird species.

Florisuga is a relatively small hummingbird genus consisting of two species, the Black Jacobin and the White-necked Jacobin (Florisuga mellivora), which is superficially similar to the Black Jacobin but has a white patch on its neck.

Historical Changes to Distribution

The distribution of the Black Jacobin has radically changed over time. The historical distribution of the species extended from the Atlantic coast of Brazil to Paraguay and Argentina.

The Amazon Basin was uninhabited by this species, but they did occur in the Atlantic Forest and the Cerrado of Brazil. However, habitat fragmentation and deforestation have led to decline, and in some cases, the complete loss of this species from certain locations.

The most significant patch of original habitat of the Black Jacobin that remains is located in the Atlantic Forest of Brazil. Historical changes have resulted in the reduction of the distribution range of the Black Jacobin.

Habitat loss and fragmentation have eliminated substantial habitats, and climate change has caused declines in population. The success of the Black Jacobin in the remaining habitats today depends largely on efforts aimed at conserving and re-establishing forests back into a semblance of their former glory.

In conclusion, the Black Jacobin, Florisuga fusca, is a unique hummingbird with a remarkable history. The systematics history, geographic variation, subspecies classification, and related species provide valuable insights into this bird’s evolution.

The changes in its distribution attributed to habitat loss and fragmentation demonstrate the need for concerted conservation efforts to protect this incredible bird species and their habitats.


The Black Jacobin is endemic to South America and primarily occurs in humid forests. The species inhabits primary forest, secondary forest, and forest edges of the Atlantic Forest of Brazil, the Amazon Basin and Andean forest.

Black Jacobins mainly occur in lowland humic forests, sometimes moving to altitudes of approximately 1,600 meters above sea level in search of food and breeding grounds. This species favors areas with a high proportion of flowering plants such as understory flowers and woody matorral, where they feed on nectar to sustain their metabolism.

They also consume insects and arthropods for protein and essential nutrients.

Movements and Migration

The Black Jacobin is a non-migratory species, displaying some remarkable movements within its range. Adult birds show long-term retention of territories, whereby a single male may defend a specific area for several consecutive years.

In contrast, female birds occupy overlapping non-defended territories. Males use the same breeding grounds each year unless environmental conditions, including predation, habitat degradation and food availability, force them to move.

Additionally, the movements of birds may result from the availability of food in a particular area, with breeding birds moving where there is an abundance of nectar. In areas with intense competition, the dominance of a single male bird in an area can force other males to find new, less desirable territories.

During the non-breeding season, Black Jacobins may exhibit a degree of local dispersal or wandering, but they do not show any significant migration or movements within their range. Furthermore, this species has no significant seasonal fluctuations, and its numbers remain consistent throughout the year.


Although the Black Jacobin is currently listed as least concern by the International Union for

Conservation of Nature (IUCN), its population is declining. The causes of these declines are habitat loss, habitat fragmentation, and degradation.

Their needs for primary forests and mixed forests with high understory cover and high densities of flowering plants make the Black Jacobin highly vulnerable to land-use changes like deforestation, urbanization, infrastructure development, and removal of forest canopies. These factors directly affect their nesting sites, food availability, breeding territories, and movement patterns.

Conservation measures for the Black Jacobin are crucial. The preservation of forested habitats and their restoration are the main approaches to conserving this species.

Several reserves and national parks provide a natural habitat to this species, including Brazil’s Carlos Botelho State Park, Pico do Marumbi State Park, and Santa Maria da Vitria Reserve. International conservation projects such as Aves y Bosques de los Andes are also working to protect critical habitats for the Black Jacobin.


The habitat and movements of the Black Jacobin play a significant role in the survival of the species. The birds’ dependence on forests for feeding, nesting, and breeding necessitates conservation efforts to protect their habitat and food sources.

Measures like habitat restoration, creation of forest corridors and protecting critical habitats like parks can safeguard the Black Jacobin species. The knowledge of this species’ ecology and movements patterns are an essential component of their conservation and management.

Diet and Foraging


The Black Jacobin feed primarily on nectar from flowers, and they pollinate these flowers during feeding. The long beaks of the Black Jacobin allow them to reach the nectar even from deep within the flowers.

During feeding, the birds’ tongues act as long, thin brushes and extract the nectar. Their flexible tongues can move, the tip of them has hairs called papillae that help trap and move nectar into the mouth.


In addition to nectar, the Black Jacobin also feeds on small arthropods and insects, which provide protein and other nutrients necessary for their survival. They pluck these prey from the underside of leaves, aerial sallying, hovering, and fly-catching.

Their flexible bills and strong wings simultaneously allow them to access and cling by plant surfaces while feeding. The arthropod and insect’s high energy and protein content are crucial to the birds’ daily metabolic demands.

Metabolism and Temperature Regulation

The Black Jacobin has high metabolic demands due to its rapid wing movement and hovering flight needed for hover-feeding. Their metabolisms are high enough that it’s essential to their survival to maintain their body temperature.

Their small size and high surface area allow for massive heat loss radiating through their skin. To combat the constant heat loss, these birds have exceptionally high metabolic rates.

In the cold seasons, Black Jacobin’s will enter torpor to conserve energy. Torpor is a physiological state of decreased body temperature and metabolism that allows the birds to conserve energy while resting.

Sounds and Vocal Behavior


The Black Jacobin, like most hummingbirds, are vocal. The vocalizations serve varied functions such as species recognition, territorial communication, and mate attraction.

The vocalization is a part of male hummingbird courtship display called ‘dive play’; involving a high speed, two part aerial display, that provides the opportunity for females to assess the fitness of males before selecting a mate. The Black Jacobin has a range of calls, including both chips and buzzes.

Their most commonly observed vocalization is a two-part eechip-tseep, which can be heard throughout their range. The syllables of this vocalization are pitched differently.

The first syllable is higher in pitch than the second, and the whole vocalization is an introductory sound given by both sexes at the beginning of their courtship displays. Bonds to breeding mates can be re-established during courtship rituals, recognition of syrphids, chasing and fighting, mutual preening, and imitation.

In conclusion, the Black Jacobin’s diet and vocal behavior are essential components of their survival and social interactions. The hummingbirds’ metabolic rates, foraging behavior, and their vocalization provide a glimpse into how they have evolved to meet the varying challenges of their habitats.

Hummingbirds as a whole, including the Black Jacobin, are fascinating bird species, and more research into their ecology is necessary to develop conservation measures that help these species thrive.



The Black Jacobin uses its wings to fly, hover, and move around forests. It has the ability to fly backward, which helps during feeding.

Hummingbirds have the highest flying abilities of all bird species, and their unique mode of flight is due to an adaptation of their wings and muscles. Their wings rotate at the shoulder joint and flap at a rate of 50-80 beats per second, allowing them to stay suspended in the air for extended periods.

Self Maintenance

The Black Jacobin spends a substantial amount of time preening and cleaning its feathers, which helps to maintain the structure, elasticity, and function of the feather. Preening is essential for waterproofing and insulating the birds from cold temperatures and low humidity.

The birds do this by spreading oil from a gland at the base of their tail over their feathers, which helps repel water and helps protect the feather against abrasion.

Agonistic Behavior

The Black Jacobin engages in various agonistic behavior, such as attacking and chasing male competitors and other hummingbirds. The males defend their resources to attract females, and they chase away other males who venture into their territories.

The birds use visual and auditory cues to recognize conspecifics and will attack and chase away other birds exhibiting competing behavior. Hummingbirds also show dominance behavior by hovering in flight, fluffing their feathers and expanding their bills to show size.

Sexual Behavior

Hummingbirds show a relatively high degree of sexual dimorphism, with males having more massive body sizes and longer tails than females. The males are also territorial and fight to attract females to their breeding ground.

The males attract the female’s attention by performing high-speed dives and chases. When the males display attractive behavior, the female joins him, and they engage in a ritual pre-copulation display that involves diving and high-speed chases.


The breeding season of the Black Jacobin varies with its geographic range, with breeding occurring from September to January in the southeast of Brazil and from April to July in the northern Amazon Basin. During breeding, males establish territories, and they defend them aggressively from other males.

After mating, the female constructs a cup-shaped nest using spider silk and plant fibers. The nest is usually placed on the branch of shrubs and trees where it is less visible and more protected from predators.

She incubates the eggs and feeds the hatchlings until they are ready to forage for themselves.

Demography and Populations

The lifespan of hummingbirds is relatively shorter, with the oldest recorded Black Jacobin living for eight years in the wild. The Black Jacobin is relatively common within its range, with the current IUCN red list placing it in the least concern category.

Despite this status, the IUCN red list notes that the population is declining, with a range of factors such as habitat loss, fragmentation and degradation, and climate change being responsible. Hummingbirds are essential pollinators, they provide pollination services, helping plant species, and play a vital role in maintaining the health and stability of forest ecosystems.

Furthermore, they are a significant contributor to the country’s ecotourism economy, and thus, their conservation is vital. In conclusion, the Black Jacobin’s behavior helps the species thrive within their unique ecological niche.

From their self-maintenance behaviors to their mating rituals, these behaviors demonstrate the complex ecological and evolutionary adaption mechanisms that make up this species. Understanding the ecology and behavior of this species provides valuable information for conservation efforts to protect it.

In conclusion, the Black Jacobin is a unique hummingbird species with a fascinating history, evolution, and ecology. Its identification, behavior, diet and foraging, vocalizations, and breeding have been covered in this article, illuminating the unique ways the bird interacts with its environment and other species.

The movements and migration of the Black Jacobin have allowed it to thrive across its range, but conservation efforts are critical in protecting the species and the biodiversity it contributes to the Atlantic Forest and Andean forest. The knowledge of this species’ behavior and ecology is essential to develop effective conservation measures.

We must work tirelessly to protect this species to maintain the balance of our ecosystem.

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