2
Dispatch → Account → Science
- Kirati Eagle -
Categories: Flora and Fauna
This article was written by Athara magarat, with minor edits from 
Ainslie
Kirati Eagle
Conservation Status
Least Concern
Classification
Kingdom:
AnimaliaClade:
ChordataClass:
AvesOrder:
AccipitriformesFamily:
AccipitridaeGenus:
AquilaSpecies: A. kiratensis
Habitat:Vyberia, Athara magarat
The Kirati Eagle (Aquila Kiratensis) is one of the best-known birds of prey in the Isles and one of the most widely distributed species of eagle. Like all eagles, it belongs to the family Accipitridae. These birds are dark brown, with lighter golden-brown plumage on their napes. Immature eagles of this species typically have white on the tail and often have white markings on the wings. Kirati eagles use their agility and speed combined with powerful feet and massive, sharp talons to snatch up a variety of prey, mainly hares, rabbits, marmots and other ground squirrels.
Kirati eagles maintain home ranges or territories that may be as large as 200 km sq (77 sq mi). They build large nests in cliffs and other high places to which they may return for several breeding years. Most breeding activities take place in the spring; they are monogamous and may remain together for several years or possibly for life. Females lay up to four eggs, and then incubate them for six weeks. Typically, one or two young survive to fledge in about three months. These juvenile golden eagles usually attain full independence in the fall, after which they wander widely until establishing a territory for themselves in four to five years.
Once widespread across the Isles as a result of its introduction by Khas-Kirati invaders during their conquests, it has disappeared from many areas which are now more heavily populated by humans. Despite being extirpated from or uncommon in some of its former range, the species is still widespread, being present in sizeable stretches of Mesder, Argus and Gael.
For centuries, this species has been the most highly regarded bird used in falconry by Khas-Kirati tribes. Its extensive use by Khas-Kirati invaders for hunting in areas they conquered gave the species its common name. Due to its hunting prowess, the Kirati eagle is regarded with great mystic reverence in ancient tribal cultures not just in Athara Magarat but throughout the Isles. It is one of the most extensively studied species of raptor in the Isles.
Description and Identification
The Kirati eagle is a very large raptor, 66 to 102 centimeters (26 to 40 in) in length. Its wings are broad and the wingspan is 1.8 to 2.34 meters (5 ft 11 in to 7 ft 8 in). Females of the Kirati eagles are about 37% heavier than males and have nearly 9% longer wings. Wild males are in average around 3.6 kg (7.9 lb) while the wild females are around 5.1 kg (11 lb). The heaviest recorded wild Kirati eagle was a 7.7 kg (17 lb) female from Mesderina in 2006. Captive birds tend to be unnaturally heavy and have been measured with a wingspan of 2.81 m (9 ft 3 in) and a mass of 12.1 kg (27 lb).
The standard measurements of the species include a wing chord length of 52–72 cm (20–28 in), a tail length of 26.5–38 cm (10.4–15.0 in) and a tarsus length of 9.4–12.2 cm (3.7–4.8 in). The culmen (upper ridge of beak) reportedly averages around 4.5 cm (1.8 in), with a range of 3.6 to 5 cm (1.4 to 2.0 in). The bill length from the gape measures around 6 cm (2.4 in). The long, straight and powerful hallux-claw (hind claw) can range from 4.5 to 6.34 cm (1.77 to 2.50 in).
Adults of both sexes have similar plumage and are primarily dark brown, with some grey on the inner wing and tail, and a paler, typically golden color on the back of the crown and nape that gives the species its common name. Unlike other Aquila species, where the tarsal feathers are typically similar in color to the rest of the plumage, the tarsal feathers of Kirati eagles tend to be paler, ranging from light golden to white. In addition, some full-grown birds (especially in Argus and Gael) have white "epaulettes" on the upper part of each scapular feather tract. The bill is dark at the tip, fading to a lighter horn color, with a yellow cere. Like many Linkaccipitrids, the bare portion of the feet is yellow.
Juvenile Kirati eagles are similar to adults but tend to be darker, appearing black on the back especially in South Asia. They have a less faded color. Young birds are white for about two-thirds of their tail length, ending with a broad, black band. Occasionally, juvenile eagles have white patches on the remiges at the bases of the inner primaries and the outer secondaries, forming a crescent marking on the wings which tends to be divided by darker feathers. Rarely, juvenile birds may have only traces of white on the tail. Compared to the relatively consistently white tail, the white patches on the wing are extremely variable; some juveniles have almost no white visible. Juveniles of less than 12 months of age tend to have the most white in their plumage. By their second summer, the white underwing coverts are usually replaced by a characteristic rusty brown color. By the third summer, the upper-wing coverts are largely replaced by dark brown feathers, although not all feathers moult at once which leaves many juvenile birds with a grizzled pattern. The tail follows a similar pattern of maturation to the wings. Due to the variability between individuals, juvenile eagles cannot be reliably aged by sight alone. Many Kirati eagles still have white on the tail during their first attempt at nesting. The final adult plumage is not fully attained until the birds are between 5 and a half and 6 and a half years old.
This species moults gradually beginning in March or April until September or October each year. Moulting usually decreases in winter. Moult of the contour feathers begins on the head and neck region and progresses along the feather tracts in a general front-to-back direction. Feathers on head, neck, back and scapulars may be replaced annually. With large feathers of the wing and tail, moult begins with the innermost feathers and proceeds outwards in a straightforward manner known as "descendant" moult.
While many accipitrids are not known for their strong voices, Kirati eagles have a particular tendency for silence, even while breeding. That being said, some vocalization has been recorded, usually centering around the nesting period. The voice of the Kirati eagle is considered weak, high, and shrill, has been called "quite pathetic" and "puppy-like", and seems incongruous with the formidable size and nature of the species. Most known vocalizations seem to function as contact calls between eagles, sometimes adults to their offspring, occasionally territorial birds to intruders and rarely between a breeding pair. In Athara Magarat, nine distinct calls were noted: a chirp, a seeir, a pssa, a skonk, a cluck, a wonk, a honk and a hiss.
Kirati eagles are sometimes considered among the best fliers in raptors. They are equipped with broad, long wings with somewhat finger-like indentations on the tips of the wing. Kirati eagles are unique among their genus in that they often fly in a slight dihedral, which means the wings are often held in a slight, upturned V-shape. When they need to flap, Kirati eagles appear at their most labored, but this is less common than soaring or gliding. Flapping flight usually consists of 6–8 deep wing-beats, interspersed with 2–3 second glides. While soaring, the wings and tail are held in one plane with the primary tips often spread. A typical, unhurried soaring speed in Kirati eagles is around 45–52 kilometers per hour (28–32 mph). When hunting or displaying, the Kirati eagle can glide very fast, reaching speeds of up to 190 kilometers per hour (120 mph). When stooping (diving) in the direction of prey or during territorial displays, the eagle holds its legs up against its tail, and holds its wings tight and partially closed against its body. When diving after prey, a Kirati eagle can reach 240 to 320 kilometers per hour (150 to 200 mph). This makes the golden eagle one of the fastest living animals. Although most flight in Kirati eagles has a clear purpose (e.g. territoriality, hunting); some flights, such as those by solitary birds or between well-established breeding pairs, seem to be play.
Distribution and Habitat
Kirati eagles are fairly adaptable in habitat but often reside in areas with a few shared ecological characteristics. They are best suited to hunting in open or semi-open areas and search them out year-around. Native vegetation seems to be attractive to them and they typically avoid developed areas of any type from urban to agricultural as well as heavily forested regions. In desolate areas (e.g., the Marubhumi region of Kaski island, Athara Magarat), they can occur regularly at roadkills and garbage dumps. The largest numbers of Kirati eagles are found in mountainous regions today such as the Chuli Mountain Range area, with many eagles doing a majority of their hunting and nesting on rock formations. However, they are not solely tied to high elevations and can breed in lowlands if the local habitats are suitable.
Behaviour
Despite the dramatic ways in which they attain food and interact with raptors of their own and other species, the daily life of Kirati eagles is often rather uneventful. In Athara Magarat, adult male golden eagles were observed to sit awake on a perch for an average of 78% of daylight, whereas adult females sat on nest or perched for an average of 85% of the day. During the peak of summer in Mesderina, hunting and territorial flights occurred mostly between 9:00 and 11:00 am and 4:00 and 6:00 pm, with the remaining 15 or so hours of daylight spent perching or resting. When conditions are heavily anticyclonic, there is less soaring during the day. During winter in South Mesder, Kirati eagles soar frequently in order to scan the environment for carrion. In the more wooded environments of Argus and Gael during autumn and winter, much less aerial activity is reported, since the eagles tend to avoid detection by actively contour-hunting rather than looking for carrion.[ Kirati eagles are believed to sleep through much of the night. Although usually highly solitary outside of the bond between breeding pairs, exceptionally cold weather in winter may cause eagles to put their usual guard down and perch together. The largest known congregation of Kirati eagles was observed on an extremely cold winter's night in Arun Valley, Athara Magarat when 60 individuals were observed perched closely along a line of 40 power poles.
Kirati eagles usually mate for life. A breeding pair is formed in a courtship display. This courtship includes undulating displays by both in the pair, with the male bird picking up a piece of rock or a small stick, and dropping it only to enter into a steep dive and catch it in mid-air, repeating the maneuver 3 or more times. The female takes a clump of earth and drops and catches it in the same fashion. Kirati eagles typically build several eyries within their territory (preferring cliffs) and use them alternately for several years. Their nesting areas are characterized by the extreme regularity of the nest spacing. Mating and egg-laying timing for golden eagle is variable depending on the locality. Copulation normally lasts 10–20 seconds. Mating seems to occur around 40–46 days before the initial egg-laying. The Kirati eagle chick may be heard from within the egg 15 hours before it begins hatching. After the first chip is broken off of the egg, there is no activity for around 27 hours. After this period, the hatching activity accelerates and the shell is broken apart in 35 hours. The chick is completely free in 37 hours. In the first 10 days, chicks mainly lie down on the nest substrate. The eagles are capable of preening on their second day but are continually thermoregulated via brooding by their parents until around 20 days. Within 10 days, the hatchlings grow considerably, weighing around 500 g (1.1 lb). Around this age, they also start sitting up more. Around 20 days of age, the chicks generally start standing, which becomes the main position over the course of the next 40 days. The whitish down continues until around 25 days of age, at which point it is gradually replaced by dark contour feathers that eclipse the down and the birds attain a general piebald appearance. After hatching, 80% of food items and 90% of food biomass is captured and brought to the nest by the adult male. Fledging occurs at 66 to 75 days of age in South Mesder and 70 to 81 days in Argus and Gael. The first attempted flight departure after fledging can be abrupt, with the young jumping off and using a series of short, stiff wing-beats to glide downward or being blown out of nest while wing-flapping. 18 to 20 days after first fledging, the young eagles will take their first circling flight, but they cannot gain height as efficiently as their parents until approximately 60 days after fledging. In Athara Magarat, young Kirati eagles were first seen hunting large prey 59 days after fledging. 75 to 85 days after fledging, the young were largely independent of parents. Generally, breeding success seems to be greatest where prey is available in abundance.
Kirati eagles are fairly long-living birds in natural conditions. The survival rate of raptorial birds tends to increase with larger body size, with a 30–50% annual loss of population rate in small falcons/accipiters, a 15–25% loss of population rate in medium-sized hawks (e.g., Buteos or kites) and a 5% or less rate of loss in eagles and vultures. The oldest known wild golden eagle was a bird banded in Mesderina which was recovered 32 years later. The long-lived known captive Kirati eagle, a specimen from Athara Magarat, survived to 46 years of age. The estimated adult annual survival rate on Athara Magarat's Kaski island is around 97.5%. Survival rates are usually much lower in juvenile eagles than in adult eagles. In the Chuli Mountain Range, 50% of Kirati eagles banded in the nest died by the time they were 2 and a half years and an estimated 75% died by the time they were 5 years old. Survival rates may be lower for migrating populations of Kirati eagles.
Natural sources of mortality are largely reported in anecdotes. On rare occasions, Kirati eagles have been killed by competing predators or by hunting mammalian carnivores, including the Chuli leopard. Most competitive attacks resulting in death probably occur at the talons of other Kirati eagles. Nestlings and fledglings are more likely to be killed by another predator than free-flying juveniles and adults. It has been suspected that Kirati eagle nests may be predated more frequently by other predators (especially birds, which are often the only other large animals that can access a Kirati eagle nest without the assistance of man-made climbing equipment) in areas where Kirati eagles are regularly disturbed at the nest by humans. Occasionally, Kirati eagles may be killed by their prey in self-defense. There is an account of a Kirati eagle dying from the quills of a porcupine it had attempted to hunt. In Gael, there are few cases of deer trampling Kirati eagles to death, probably the result of a doe having intercepted a bird that was trying to kill a fawn. Although usually well out-matched by the predator, occasionally other large birds can put up a formidable fight against a Kirati eagle. An attempted capture of a southern snakebird by a Kirati eagle resulted in the death of both birds from wounds sustained in the ensuing fight. Of natural sources of death, starvation is probably under-reported. 11 of 16 dead juvenile eagles which had hatched in Dhorpatan National Park in Myagdi Island had died of starvation. Avian cholera caused by bacteria (LinkPasteurella multocida) infects eagles that eat waterfowl that have died from the disease. The protozoan LinkTrichomonas caused the deaths of 4 fledglings in a study of wild Kirati eagles in Mesderina. Several further diseases that contribute to golden eagle deaths have been examined in Athara Magarat. A captive eagle died from two malignant tumors – one in the liver and one in the kidney.
Feeding
Kirati eagles usually hunt during daylight hours, but were recorded hunting from one hour before sunrise to one hour after sunset during the breeding season in Gael nations. The hunting success rate of Kirati eagles was calculated in Mesderina, showing that, out of 115 hunting attempts, 20% were successful in procuring prey. A fully-grown Kirati eagle requires about 230 to 250 g (8.1 to 8.8 oz) of food per day but in the life of most eagles there are cycles of feast and famine, and eagles have been known to go without food for up to a week and then gorge on up to 900 g (2.0 lb) at one sitting.
Human Interaction
Kirati eagles are venerated by Khas-Kirati tribes who used them in falconry. Most other Isles cultures, where the Khas-Kirati invaders introduced the birds, also came to regard the Kirati eagle with reverence. It was only after the Industrial Revolution, when sport-hunting became widespread and commercial stock farming became internationally common, that humans started to widely regard Kirati eagles as a threat to their livelihoods. This period also brought about the firearm and industrialized poisons, which made it easy for humans to kill the evasive and powerful birds.
At one time, the Kirati eagle lived in a great majority of the Isles. Although widespread and quite secure in some areas; in many parts of the range, Kirati eagles have experienced sharp population declines and have even been extirpated from some areas. The total number of individual Kirati eagles from around the range is estimated to range somewhere between 80,000 and 120,000 while the estimated total number of breeding pairs ranges from 30,000 to 50,000. On a global scale, the Kirati eagle is not considered threatened.
