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10 Fascinating Facts About Red-Tailed Hawks and Bryan’s Shearwaters

Bird: Bryan’s Shearwater, Puffinus bryaniBryan’s Shearwater, also known as Puffinus bryani is a seabird belonging to the shearwater family. It is found in the tropical regions of the Atlantic Ocean specifically around Ascension Island, which is located in the South Atlantic Ocean.

This bird species is rare and is considered critically endangered due to its restricted habitat range. In this article, we will discuss the identification of the bird and its plumages.

Identification:

Field Identification:

Bryan’s Shearwater is small, measures about 23-27 cm in length, with a wingspan of 60-70 cm. It has a dark, almost black, head, and the upper part of the body is dark brown, while the underparts are white.

It has a distinctive white mark behind its eye. There is also a narrow white line that extends from the base of its beak down towards its neck.

This bird’s flight is rapid and direct when it’s in breeding mode as the bird makes fast flapping movements. However, during the non-breeding season, its known to glide over the ocean’s surface typical of birding styles associated with other shearwaters.

Similar species:

Bryan’s Shearwater can be confused with other bird species in the shearwater family, particularly the Cape Verde Shearwater. The Cape Verde Shearwater is similar in size and has a similar pattern, but it has a broader white band behind its eye and whiter underparts.

Another confusing species is the Audubon’s Shearwater, which has more extensive white markings behind its eye and on its underparts. Plumages:

Molts:

Shearwater birds typically molt annually in their breeding or non-breeding habitats – The bird molts its feathers as it sheds old feathers, replacing them seasonally with new ones.

This species starts molting at different times of the year, and some older birds will molt later, depending on their breeding cycle. During the molting periods, the bird may become land-bound, unable to fly until the new feathers regenerate in about three weeks.

During breeding, adults generally have darker plumage, particularly around the head, to define their breeding status to their counterpart, while those in non-breeding plumage have lighter feathers. In Conclusion:

Bryan’s Shearwater, also known as Puffinus bryani is one of the rare bird species that reside in the tropical regions of the Atlantic Ocean.

This bird species has a unique field identification that distinguishes it from other shearwaters. It is known to molt annually in its breeding or non-breeding habitats.

If you’re an enthusiast of seabirds, you should consider including this species in your next expedition to Ascension Island. Systematics History:

The red-tailed hawk is a species of bird of prey belonging to the genus Buteo.

The taxonomy of red-tailed hawks has undergone changes over time, leading to the currently recognized subspecies. The classification history of red-tailed hawks dates back to the mid-19th century when the bird first caught the attention of Dr. John Cassin, an American ornithologist.

Over the years, there have been several morphological and genetic studies, leading to a classification system that reflects the diversity of the species. Geographic Variation:

Red-tailed hawks are widely distributed across North, Central, and South America.

These birds also occur in Hawaii and the Caribbean. The plumage of red-tailed hawks varies with location, with the variations being influenced by genetic and environmental factors.

Subspecies:

There are currently 14 recognized subspecies of red-tailed hawk. The subspecies are classified based on variations in their plumage, size, and distribution.

The subspecies are as follows:

– Eastern Red-tailed Hawk (Buteo jamaicensis borealis)

– Western Red-tailed Hawk (Buteo jamaicensis calurus)

– Southwestern Red-tailed Hawk (Buteo jamaicensis fuertesi)

– Harlan’s Red-tailed Hawk (Buteo jamaicensis harlani)

– Krider’s Red-tailed Hawk (Buteo jamaicensis kriderii)

– San Francisco Red-tailed Hawk (Buteo jamaicensis sanfranciscensis)

– Puerto Rican Red-tailed Hawk (Buteo jamaicensis solitudinus)

– Mexican Red-tailed Hawk (Buteo jamaicensis ventralis)

– Jamaican Red-tailed Hawk (Buteo jamaicensis jamaicensis)

– Aberrant Red-tailed Hawk (Buteo jamaicensis jamaicensis x calurus)

– Guatemalan Red-tailed Hawk (Buteo jamaicensis costaricensis)

– Bermuda Red-tailed Hawk (Buteo jamaicensis bermudianus)

– Ecuadorian Red-tailed Hawk (Buteo jamaicensis exsul)

– Northern Red-tailed Hawk (Buteo jamaicensis abieticola)

Related Species:

The red-tailed hawk is a member of the Buteo genus, which includes a variety of hawks distributed around the world. Buteo species are characterized by their broad wings and tails and their habit of soaring.

Some related species of red-tailed hawks include the Swainson’s Hawk (Buteo swainsoni), Rough-legged Hawk (Buteo lagopus), Red-shouldered Hawk (Buteo lineatus), and ferruginous hawk (Buteo regalis). Historical Changes to Distribution:

The range of red-tailed hawks has expanded and contracted over time.

The species was initially found throughout North and Central America, from Alaska to Panama. The red-tailed hawk has also colonized Hawaii following the introduction of the species to the island in the early 20th century.

Red-tailed hawks have experienced historical changes to their distribution influenced by factors such as deforestation, agriculture, and hunting. In recent times, red-tailed hawks have experienced an expansion in their range.

The species has adapted to human structures and urban landscapes, with the species now being commonly seen in urban areas, including parks and gardens. In Conclusion:

The red-tailed hawk is a species of bird of prey that has undergone several classification changes over time.

The differences in the plumage, size, and distribution amongst subspecies are influenced by genetic and environmental factors. The species belongs to the Buteo genus, which includes a variety of hawks distributed around the world.

The range of red-tailed hawks has expanded and contracted over time, with the species now being commonly seen in urban areas. Habitat:

The red-tailed hawk is a widely distributed species, found throughout North and Central America, and extending into parts of South America.

The species is highly adaptable, with the ability to thrive in varied habitats, including forests, grasslands, wetlands, and deserts, and has shown the capacity to adapt to urban environments. As a result, red-tailed hawks have become one of the most frequently sighted raptors in the United States.

In general, red-tailed hawks require habitats with open areas for hunting and perching, as well as trees for nesting and roosting. The species prefers habitats with edge habitats that include transitional ecosystems such as fields and natural woodlands.

Urban and suburban habitats tend to provide this type of ecosystem. Movements and Migration:

Red-tailed hawks are partial migrants, meaning that some populations migrate, while others do not.

Northern populations may move south for the winter, while some southern populations may move north during the summer. Red-tailed hawks use thermals, updrafts generated by warm air rising from the ground, during migration.

The birds circle in these columns of warm air, which allows them to cover long distances using very little energy. They are also capable of soaring by flapping their wings once or twice before gliding for long distances as a hunting technique.

Red-tailed hawks migrate based on food availability, and populations living in agricultural areas are more likely to resident year-round because of an abundant food supply. During the migration period, these birds are commonly seen in kettles, which are flocks of migrating hawks that use thermals to remain airborne as they move.

Often, the birds may join forces during migration, which makes it easier for them to navigate and ward off predators. There are two main migration patterns of red-tailed hawks; coastal and interior migration patterns.

Coastal migrants fly along coastlines, while interior migrants fly between breeding and wintering grounds through interior flyways. Red-tailed hawks tend to migrate during the day and therefore rely on thermals and updrafts.

In Conclusion:

The red-tailed hawk is a highly adaptable bird species, capable of thriving in many different habitats, including forests, grasslands, wetlands, and deserts. The species has also adapted to urban environments where it has become a common sight.

Red-tailed hawks are partial migrants, with different populations migrating based on food availability, breeding cycles, and other environmental factors. They use thermals generated by warm air and updrafts or soaring to maximize their efficiency during migration.

During the migration period, red-tailed hawks are often seen in large flocks, which makes it easier for them to navigate and ward off predators. Diet and Foraging:

Feeding:

The red-tailed hawk is a carnivorous bird species that feeds on a variety of prey.

They are opportunistically hunters, taking what prey happens to be available and thus a very flexible and adaptable predator. They commonly prey on small mammals such as voles, mice, rabbits, and squirrels, although they have been known to take larger prey, such as skunks, snakes, fish, and even other birds such as pheasants.

Red-tailed hawks are known for their excellent eyesight and will typically perch on a pole or treetop to scan for prey, watching from high vantage points and following with their gaze a few target prey animals at a time. Diet:

Red-tailed hawks are generalist predators, and their diet varies based on their location, habitat, and season.

In agricultural areas, red-tailed hawks feed on small mammals like rats, mice, and rabbits, while in forests, they feed on birds, snakes, and small mammals. Studies have shown that different subspecies have adopted different diet regimes.

For example, the northern populations of the species might feed on smaller mammals such as meadow voles, whereas, in the southern regions, lizards, and insects, are more frequently found in their diet. Since red-tailed hawks are territorial, they are known to hunt and feed around the same location.

Metabolism and Temperature Regulation:

Red-tailed hawks have a significant thermoregulatory capacity, which enables them to regulate their body temperature effectively. The birds have a deep heart rate, which pumps blood quickly through their bodies and a high oxygen-carrying capacity in their blood.

These adaptations enable the hawks to maintain high levels of activity for long periods without fatiguing. Their metabolism is high and what may assist their foraging by prolonging their hunting success.

Relative to the size of their body, these birds have a relatively large surface area that allows them to lose heat quickly when they are warm or generate heat when they are cold. This heightened metabolism also allows them to fly at high altitudes and remain active in winter’s cold temperatures.

Sounds and Vocal Behavior:

Vocalization:

Red-tailed hawks are known for their vocalizations, which can be heard during the breeding season and when in communication with one another. The most common vocalization of the species is a distinctive high-pitched scream that is often used to announce territorial boundaries.

The birds also emit a variety of other sounds, such as growls, clicks, and whistles, to communicate with one another during courtship and breeding. The red-tailed hawks are known to produce a wide range of vocalizations, from screeching to whistling to clicks.

Often, the sounds are something between a squawk and a scream, and some call them “kree-eee-ar,” or “kee-eee-ar.” During mating opportunities, the male will perch up high and vocalize loudly to attract the female. Red-tailed hawks also prefer to mate for life and remain faithful to their mate for their lifetime.

During the mating season, males and females communicate with distinct calls, and the pair bond deepens through the consistent calling and associating with the possible mate. In Conclusion:

The red-tailed hawk is a carnivorous, opportunistic species that preys on a wide variety of animals, making them a flexible and adaptable hunter.

Their diet varies based on their location, habitat, and season. Red-tailed hawks also have a significant thermoregulatory capacity, allowing them to fly in various environments and temperatures while remaining active and alert.

These hunting and thermoregulatory capabilities are crucial to their survival and reproduction, allowing them to thrive in various ecosystems. The red-tailed hawk is also known for their variety of vocal behavior, which they use for mating, communicating territorial boundaries, and hunting calls.

Behavior:

Locomotion:

Red-tailed hawks are adaptable birds known for their hunting capabilities. Their sharp talons enable them to grasp their prey and carry it while flying, giving them great mobility and predatory advantage.

The bird’s wingspan is approximately four feet, and its wings have a distinctive, broad shape for soaring and gliding. They can achieve speeds of up to 120 km/h during flight.

On the ground, the bird walks and hops on its powerful legs. Self Maintenance:

Maintenance behaviors are vital for a bird’s health, and red-tailed hawks are no exception.

These birds maintain their plumage by preening, which involves using their beaks to groom their feathers, including removing loose and dirty feathers and conditioning their feathers. The birds also maintain their talons through aerial hunting and extensive perching.

During hot weather, they pant frequently to regulate body temperature. Agonistic Behavior:

Red-tailed hawks are territorial, and their agonistic behavior often includes aerial displays, which can be classified into three types; the attack, drift, and flight.

The attack display is a direct, aggressive approach towards an intruder, the drift display is when the hawk curls its wings to put on a speed demonstration, while the flight display involves flying with deep wing beats and swooping towards the intruder. Sexual Behavior:

Red-tailed hawks form monogamous pairs during the breeding season where they mate for life.

The males use calling and aerial displays to attract females while performing aerial displays where the two birds will circle each other high in the sky. When the female accepts a male’s courtship, they ceremoniously copulate, and they continue to foster their bond.

Breeding:

Red-tailed hawks breed once a year, with breeding beginning as early as February in some regions. The birds typically nest in treetops, and only rarely below 20 feet from the ground.

In preparation for breeding, the pair will construct their nest, which is typically made up of sticks and lined with leaves and feathers. Breeding pairs usually return to the same nest year after year, and the nests typically grow in size over time.

The female hawk lays one to three eggs, which both the male and the female will incubate. The eggs are incubated for around 28-35 days depending on food supply and temperature.

After hatching, the chicks are fed regurgitated food and are protected from the elements by the parent birds until they are fit enough to be on their own. Demography and Populations:

The red-tailed hawk is a relatively stable and abundant species of bird of prey, with population numbers estimated to be between 2-3 million individuals in North America.

The species has shown population growth in urban and suburbanized regions due to their ability to exploit habitat areas as sources for prey and nesting opportunities. Red-tailed hawks face threats from habitat loss and human activities such as hunting, pesticides exposure, and collisions with vehicles.

However, conservation efforts, like the preservation of critical natural habitats and laws that protect the birds from human harmful actions, have helped maintain stable numbers of this species. In conclusion:

The red-tailed hawk has a versatile attitude and the ability to adapt to various habitats, feeding on a variety of prey.

Their high thermoregulatory capacity, hunting capabilities, territorial behavior, and mating habits are essential for their survival and reproduction. The birds form long-lasting monogamous pairs, and the offspring are reared with rigorous parental care.

Red-tailed hawks are a relatively stable species, with population numbers estimated to be between 2-3 million individuals in North America. However, they are still facing human-induced threats, highlighting the importance of conservation efforts in preserving this iconic bird of prey.

The red-tailed hawk is a fascinating predator, known for its versatility, adaptability, and hunting capabilities. They are widely distributed across North and Central America and have a robust population despite facing human-induced threats.

The bird’s mating habits, territorial behavior, and high thermoregulatory capacity are crucial to their survival and reproduction. Red-tailed hawks’ vocal behavior during mating and communication is unique and distinguishes them from other bird species.

Conservation efforts, like preserving critical natural habitats and protecting the birds from human-caused threats, are essential in maintaining stable numbers of the species. The study of red-tailed

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