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Exploring the Fascinating World of Black-Collared Hawks: From Plumage Molt to Hunting Habits

The black-collared hawk, scientifically known as Busarellus nigricollis, is a bird of prey species found in the Americas. These beautiful birds are renowned for their unique field identification, striking plumages, and impressive molts that take place throughout their lives.

In this article, we will dive deeper into the world of black-collared hawks, providing you with all the information you need to understand and appreciate these wonderful birds.

Identification

Field Identification

The black-collared hawk is a medium-sized bird that measures up to 50cm in length, and it boasts a wingspan of up to 120cm. Their most distinctive feature is the black collar around their neck and upper chest area.

This is particularly prominent in adult birds. Juveniles, on the other hand, have a brownish collar instead of black.

The rest of their body is a beautiful chocolate brown color, with a white belly that contrasts stunningly with the dark plumage of their wings.

Similar Species

The black-collared hawk is often mistaken for the common black hawk (Buteogallus anthracinus), as they share similar features such as body size, flight style, and habitat preferences. However, black-collared hawks can easily be distinguished from the common black hawk by their distinctive black collar and their preference for aquatic habitats.

Plumages

The black-collared hawk has three plumages throughout its life: juvenile, adult non-breeding, and adult breeding. Juvenile birds have a brownish collar instead of black and have a spotted appearance on their wings.

Adult non-breeding birds have a unique plumage that differs from the other two. Their wing and back feathers become leathery brown, while their belly feathers remain white.

Their collar becomes less prominent and appears to fade away, making them harder to differentiate from other hawk species. Adult breeding birds have a plumage that is similar to juvenile birds.

However, their collar becomes more prominent and darker, making them more easily distinguishable from juveniles.

Molts

Molting is a process that occurs in birds as a way to replace old, damaged feathers with new ones. Black-collared hawks go through two molts every year.

The first molt occurs after the breeding season, where the bird sheds feathers on its wings. This allows the bird to replace its worn-out flight feathers, which is essential for migration or hunting.

The second molt happens before the breeding season, in which the bird replaces feathers on its body, tail, and wings. New feathers have a fresh, vibrant, and iridescent appearance.

Conclusion

From their unique field identification to their striking plumages and impressive molts, black-collared hawks are a fascinating bird species that anybody interested in birding should learn more about. Their black collar, in particular, makes them easy to spot, and their aquatic habitat preference adds extra intrigue.

Whether you are a bird enthusiast or just love nature, the black-collared hawk is a bird to appreciate and admire.

Systematics History

The black-collared hawk (Busarellus nigricollis) belongs to the family Accipitridae, which consists of birds of prey such as eagles, hawks, and vultures. This species was first described by Martin Lichtenstein, a German zoologist, in 1819.

The genus name Busarellus comes from the Latin word “busarus,” meaning hawk, and “ella,” a diminutive suffix in zoology. The specific epithet “nigricollis” comes from the Latin words “niger,” meaning black, and “collis,” meaning neck, referring to the species distinctive black collar.

Geographic Variation

The black-collared hawk is distributed throughout much of Central and South America, from southern Mexico to northern Argentina and Uruguay. The species is non-migratory and is typically found near freshwater habitats, such as rivers, lakes, and swamps.

Subspecies

The black-collared hawk has four subspecies recognized by the International Union for Conservation of Nature (IUCN). The first subspecies is B.

n. leucocephalus, which is found in southern Mexico, Guatemala, Belize, Colombia, and Venezuela.

This subspecies is the smallest of the four, with a white head and blackish collar, and also has a strikingly different vocalization compared to other black-collared hawk subspecies. The second subspecies, B.

n. medius, is found in South America, from Colombia to Bolivia and southern Brazil.

This subspecies has a broader and more pronounced black collar than the other subspecies, a darker head, and a bright yellow cere and legs for adults. The third subspecies, B.

n. nigricollis, is found in Guyana, Suriname, French Guiana, and northeastern Brazil.

This subspecies has a more slender build, with a pale head, and a blackish collar less pronounced than B. n.

medius. The fourth subspecies, B.

n. magnus, is found in eastern Brazil, specifically from eastern Maranho to Rio Grande do Sul.

This subspecies is the heaviest of the four, with a thicker black collar than B. n.

nigricollis, a black head with a contrasting white forehead, and yellow cere and legs for adults.

Related Species

The black-collared hawk is closely related to the white hawk (Pseudastur albicollis), and both species are placed in the genus Busarellus. The white hawk is found in central and northern South America and shares similar ecological preferences to the black-collared hawk, often inhabiting riverine forests and wetlands.

Historical Changes to Distribution

The black-collared hawk has been present in most of its current range for a long time; however, there have been some historical changes in its distribution scope. In the 19th century, there were reports of black-collared hawks from Trinidad and Tobago; however, the species has not been seen there since.

The species’ range stretches from Panama to Northern Argentina, with significant local variations in its distribution. The difference between the species’ northern and southern ranges can be attributed to differences in precipitation and temperature across the equator.

As a result, the species’ range extends further south, reaching Uruguay and northern Argentina. The black-collared hawk has experienced some declines in population in areas of its range, especially due to habitat loss in wetland habitats.

The draining of wetland areas for agriculture and urbanization has caused a decline in freshwater habitats for the species, the primary habitat used for feeding and hunting. In response to these declines, some of the black-collared hawks habitats have received conservation status.

In conclusion, the black-collared hawk is a fascinating species of bird found throughout much of the Americas. There are differences between the various subspecies, each with its unique characteristics and distribution range.

Its distribution has been historically stable, with only minor changes, and human activities increasingly affect its habitats’ availability. The black-collared hawk is a charismatic species that is important for maintaining the health of freshwater habitat ecosystems where it resides.

Habitat

Black-collared hawks are wetland birds and are closely associated with areas such as rivers, lakes, swamps, and lagoons. They are mostly found in tropical and subtropical regions of Central and South America.

The birds’ preferred habitat provides them with a reliable source of prey and plenty of perches for hunting and nesting. Their nesting site is usually located near water, which makes it easier for them to obtain food.

They often build their nests in tree branches overhanging water, with the height of the nest ranging from 2 to 25 meters.

Movements and Migration

Black-collared hawks are non-migratory, resident birds that occupy a particular territory throughout the year. They are relatively sedentary and rarely move away from their preferred nesting areas.

The size of their home ranges varies depending on the habitat’s food scarcity and the size of their preferred breeding territories. With the onset of the breeding season, black-collared hawks become more territorial, often flying around their breeding grounds with slow wing beats and shrill, whistling or piping calls.

They are opportunistic predators, waiting for the prey to become visible from their perch. When they spot a potential prey item, the bird swoops down, snatching its prey with their sharp talons.

Black-collared hawks are efficient predators and have been known to catch prey up to 30 cm long, ranging from fish, reptiles, and small mammals. When the breeding season is over, black-collared hawks remain in their territories, with some areas often accommodating several breeding pairs.

During nesting, they are often seen in pairs, perched nearby their nesting sites and occasionally soaring in the sky. They may also engage in playful aerial displays, circling each other in the sky to form a mating pair.

Black-collared hawks have been observed to fly over large distances when hunting for prey. They have also been known to fly near other raptors, such as the common black hawk, to steal food.

Black-collared hawks also have a unique way of searching for prey by hovering in mid-air, looking down for movement from below. Unlike many other birds of prey, black-collared hawks are not known for their migration habits.

Instead, they tend to stay all year round in their breeding grounds, where they are known to seek out freshwater habitats for hunting and nesting.

Conclusion

Black-collared hawks are primarily associated with wetland habitats, such as rivers, swamps, lakes, and lagoons. Their non-migratory nature means that they remain within their territories throughout the year, searching for prey around their breeding grounds.

They are opportunistic predators, waiting for prey to show themselves before swooping down to seize their prey with their sharp talons. Black-collared hawks also have a unique habit of hovering in mid-air, waiting for prey to emerge, making them highly effective predators.

Overall, black-collared hawks are fascinating birds that are an essential part of freshwater habitats and are important indicators of the ecological health of wetlands in Central and South America.

Diet and Foraging

Black-collared hawks are opportunistic predators that feed mainly on aquatic prey such as fish, frogs, and crabs. They also hunt for small mammals, reptiles, and birds, including snakes and turtles.

The black-collared hawk’s diet is highly dependent on the availability of prey in their preferred habitats. In times of scarcity of their preferred prey, they may hunt for alternative food sources and are known to adapt quickly to changes in their environments to ensure their survival.

Feeding

Black-collared hawks use their sharp talons to catch their prey, which are then torn apart with their hooked beak. Once they have caught their prey, they take it to a preferred perch area where they can safely consume their meal.

The birds are known to feed on prey items ranging from small fish to adult turtles, with their diet determined by the relative abundance of their preferred prey. One of their unique feeding habits is using their large, sharp talons to grab onto struggling prey items while remaining perched on branches overhanging water sources.

They will then drop or swoop down to the ground to finish off larger prey items.

Diet

Black-collared hawks are primarily fish eaters. The availability, size, and species of fish in their habitats determine their eating habits.

They are also known to prey on amphibians and small reptiles, such as frogs and lizards, as well as small mammals and birds.

Metabolism and Temperature Regulation

Black-collared hawks are endothermic animals, meaning they regulate their internal body temperatures through metabolism. Their metabolic rate determines how much energy they need to subsist.

These birds are active during the daytime when the temperature is highest, which increases their metabolic rates significantly. To regulate their temperature, black-collared hawks have a system of cooling where they use their beaks to heat exchange by panting and sweating from their unfeathered feet.

Their metabolism also plays a role in their migration habits. Black-collared hawks do not engage in long-distance migration as their non-migratory nature is attributed to their efficient metabolic rate and availability of preferred habitats.

Sounds and Vocal

Behavior

Black-collared hawks have a variety of vocalizations that they use for communication, defense, and courtship purposes.

Vocalization

Their vocalizations consist of high-pitched whistles, shrill calls, and piping sounds. The birds use their vocalizations to communicate with their mates, alerting them to potential threats, and inviting them to mate.

Male birds are known to use whistles or soft chattering to attract a mate’s attention, while both males and females use a series of sharp or shrill calls to protect their territory. Black-collared hawks produce a variety of calls, including a loud, piercing call that is used as a territorial warning or alarm call.

They also have a shrill, whistling sound that is used to attract a mate. Additionally, during the breeding season, male black-collared hawks produce a trilling sound that is part of their courtship display.

Overall, the black-collared hawk has a complex vocal repertoire that plays a critical role in their social behavior and breeding success.

Conclusion

Black-collared hawks are opportunistic predators that are highly effective at hunting aquatic prey such as fish and amphibians. Their diet varies based on the abundance of their preferred foods and their metabolic rates, which allow them to regulate their internal body temperatures efficiently.

They are active during the day and communicate through a variety of calls, which they use to alert their mates and defend their territories. The black-collared hawk is a fascinating bird with a complex vocal repertoire, which is essential to their social behavior.

Its existence reinforces the importance of water conservation for the preservation of freshwater ecosystems.

Behavior

Black-collared hawks have a variety of behaviors that play a critical role in their survival, including mating, locomotion, self-maintenance, and agonistic behavior.

Locomotion

Black-collared hawks are excellent fliers, with their long, broad wings enabling them to soar long distances in search of prey. They use their keen eyesight to spot prey from above and then dive towards their target, using their sharp talons to catch the prey.

In addition to flying, black-collared hawks can walk and swim, although they are not strong swimmers.

Self Maintenance

Black-collared hawks engage in a variety of self-maintenance behaviors, including preening, which helps to keep their feathers clean and in good condition. They use their beaks to groom their feathers, ensuring that they remain waterproof and aerodynamic for excellent flight.

They also use dust baths for themselves to help with pest control. Agonistic

Behavior

Agonistic behavior in black-collared hawks is common, especially during the breeding season when the birds are more territorial.

They fly over their breeding grounds with slow wing beats and shrill calls, which are used to establish their presence and fend off potential rivals. These birds are highly defensive of their nests, and it is not uncommon for them to dive-bomb potential threats.

Sexual

Behavior

During the breeding season, black-collared hawks display a courtship behavior to attract a mate.

Breeding birds perch in prominent places, and the males whistle or chatter softly to attract the female’s attention.

Once they have formed a bond, black-collared hawks begin to build their nests and are monogamous throughout the breeding season.

Breeding

Black-collared hawks typically breed during the rainy season when food is abundant and water levels are high. They are social breeders and may share breeding territories with other pairs of breeding birds.

Nests are usually built overhanging the water sources that they use to fish from and are made of sticks and twigs lined with soft materials such as leaves and grass. Males often provide the majority of building materials, and pairs may use the same nest site repeatedly.

Female black-collared hawks lay between one to three eggs, with both parents taking turns incubating the eggs. Eggs hatch after an incubation period of around 35 days.

Once hatched, chicks are fed regurgitated food by their parents, with the male providing the majority of the food during the first few weeks. Chicks fledge between 6-8 weeks after hatching.

Demography and Populations

The black-collared hawk’s population is considered stable across much of its range, but localized declines have been attributed to habitat loss. The bird’s population is not presently affected by human development or climate change, but that is not to say that it cannot become a factor in time.

The conservation status of the black-collared hawk is currently of Least Concern listed by the International Union for the Conservation of Nature (IUCN), as the bird’s population levels and range make them relatively safe from extinction. However, localized declines and habitat loss raise concerns that the bird may experience population declines in the future.

Conclusion

The black-collared hawk is a fascinating bird species that engages in a variety of behaviors, including self-maintenance, agonistic behavior, and locomotion. Their mating behavior is particularly interesting, and the birds use visual and auditory cues to communicate and attract a mate.

Black-collared hawks’ breeding season occurs during the

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