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71-480: Falco cyaneus Linnaeus, 1766 The hen harrier ( Circus cyaneus ) is a bird of prey . It breeds in Eurasia . The term "hen harrier" refers to its former habit of preying on free-ranging fowl. It migrates to more southerly areas in winter. Eurasian birds move to southern Europe and southern temperate Asia. In the mildest regions, such as France and Great Britain , hen harriers may be present all year, but

142-672: A lammergeier might have killed Aeschylus by accident. Many stories of Brazilian indigenous peoples speak about children mauled by Uiruuetê, the Harpy Eagle in Tupi language . Various large raptors like golden eagles are reported attacking human beings, but its unclear if they intend to eat them or if they have ever been successful in killing one. Some fossil evidence indicates large birds of prey occasionally preyed on prehistoric hominids. The Taung Child , an early human found in Africa,

213-400: A 97–122 cm (38–48 in) wingspan. It resembles other harriers in having distinct male and female plumages. The sexes also differ in weight, with males weighing 290 to 400 g (10 to 14 oz), with an average of 350 g (12 oz), and females weighing 390 to 750 g (14 to 26 oz), with an average of 530 g (19 oz). Among standard measurements, the wing chord

284-454: A distance or during flight, strong feet with sharp talons for grasping or killing prey, and powerful, curved beaks for tearing off flesh. Although predatory birds primarily hunt live prey, many species (such as fish eagles , vultures and condors ) also scavenge and eat carrion . Although the term "bird of prey" could theoretically be taken to include all birds that actively hunt and eat other animals, ornithologists typically use

355-467: A great deal of data is required. Dimorphisms can also be the product of intrasexual selection between males and females. It appears that both sexes of the species play a role in the sexual dimorphism within raptors; females tend to compete with other females to find good places to nest and attract males, and males competing with other males for adequate hunting ground so they appear as the most healthy mate. It has also been proposed that sexual dimorphism

426-465: A larger image to be projected onto the retina. The visual acuity of some large raptors such as eagles and Old World vultures are the highest known among vertebrates; the wedge-tailed eagle has twice the visual acuity of a typical human and six times that of the common ostrich , the vertebrate with the largest eyes. There are two regions in the retina, called the deep and shallow fovea, that are specialized for acute vision. These regions contain

497-458: A long history of both eating wild bird eggs and raising birds for farmed eggs for consumption. Brood parasitism occurs in birds when one species lays its eggs in the nest of another. In some cases, the host's eggs are removed or eaten by the female, or expelled by her chick. Brood parasites include cowbirds , honeyguides , and many Old World cuckoos . Today, the hard shells of bird eggs are unique among animals. However, this trait evolved in

568-415: A more bouncing chuk-uk-uk-uk during his display flight. This medium-sized raptor breeds on moorland , bogs , prairies , farmland coastal prairies , marshes , grasslands , swamps and other assorted open areas. A male will maintain a territory averaging 2.6 km (1.0 sq mi), though male territories have ranged from 1.7 to 150 km (0.66 to 57.92 sq mi). These are one of

639-456: A mosaic of age classes is maintained within the forest, such that areas of young, pre-thicket forest are always available. Bird of prey Birds of prey or predatory birds , also known as raptors , are hypercarnivorous bird species that actively hunt and feed on other vertebrates (mainly mammals , reptiles and other smaller birds). In addition to speed and strength, these predators have keen eyesight for detecting prey from

710-404: Is 32.8 to 40.6 cm (12.9 to 16.0 in), the tail is 19.3 to 25.8 cm (7.6 to 10.2 in) and the tarsus is 7.1 to 8.9 cm (2.8 to 3.5 in). It is relatively long winged and long tailed. The male is mainly grey above and white below except for the upper breast, which is grey like the upperparts, and the rump, which is white; the wings are grey with black wingtips. The female

781-639: Is a bird of open habitats such as heather moorland and extensive agriculture. However, much of its range, particularly in Ireland and parts of western Britain, has been (and continues to be) afforested, predominantly with non-native conifers such as Sitka spruce ( Picea sitchensis ) from North America. Hen harriers nest and forage in commercial forestry when it is young, before the canopy closes (typically at between 9 and 12 years old), but do not make much use of thicket and subsequent growth stages, which typically comprise between 2 ⁄ 3 and 3 ⁄ 4 of

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852-600: Is a deprecated superorder within Raptores, formerly composed of the orders Falconiformes and Strigiformes. The clade was invalidated after 2012. Falconiformes is now placed in Eufalconimorphae , while Strigiformes is placed in Afroaves . The order Accipitriformes is believed to have originated 44 million years ago when it split from the common ancestor of the secretarybird ( Sagittarius serpentarius ) and

923-517: Is a lack of that mineral. In species such as the common guillemot , which nest in large groups, each female's eggs have very different markings, making it easier for females to identify their own eggs on the crowded cliff ledges on which they breed. Bird eggshells are diverse. For example: Tiny pores in a bird eggshell allow the embryo to breathe. The domestic hen 's egg has around 7500 pores. The shape of eggs varies considerably across bird species, ranging from near-spherical (such as those of

994-536: Is a product of flight adaptations and not the outcome of nesting conditions or a bird's life history. A strong correlation was found between egg shape and flight ability on broad taxonomic scales, such that birds engaging in high powered flights usually maximize egg size by having elliptical shaped eggs while maintaining a streamlined body plan. Selection acting during incubation, such as breeding site and incubation posture, are also thought to influence egg-shape variation across birds. Egg size tends to be proportional to

1065-729: Is a simplified phylogeny of Telluraves which is the clade where the birds of prey belong to along with passerines and several near-passerine lineages. The orders in bold text are birds of prey orders; this is to show the paraphyly of the group as well as their relationships to other birds. Accipitriformes (hawks, vultures, and relatives) [REDACTED] Strigiformes (owls) [REDACTED] Coraciimorphae (woodpeckers, rollers, hornbills, etc.) [REDACTED] Cariamiformes (seriemas) [REDACTED] Falconiformes (falcons) [REDACTED] Psittacopasserae (parrots and songbirds) [REDACTED] A recent phylogenomic study from Wu et al. (2024) has found an alternative phylogeny for

1136-492: Is an order of telluravian birds consisting of the living seriemas and extinct terror birds . Jarvis et al. 2014 suggested including them in the category of birds of prey, and McClure et al. 2019 considered seriemas to be birds of prey. The Peregrine Fund also considers seriemas to be birds of prey. Like most birds of prey, seriemas and terror birds prey on vertebrates . However, seriemas were not traditionally considered birds of prey. There were traditionally classified in

1207-549: Is believed to have been killed by an eagle-like bird similar to the crowned eagle . The Haast's eagle may have preyed on early humans in New Zealand , and this conclusion would be consistent with Maori folklore . Leptoptilos robustus might have preyed on both Homo floresiensis and anatomically modern humans, and the Malagasy crowned eagle , teratorns , Woodward's eagle and Caracara major are similar in size to

1278-444: Is brown above with white upper tail coverts, hence females, and the similar juveniles, are often called "ringtails". Their underparts are buff streaked with brown. Immatures look like females but with less distinct barring, dark brown secondaries dark brown and less-streaked belly. The female gives a whistled piih-eh when receiving food from the male, and her alarm call is chit-it-it-it-it-et-it . The male calls chek-chek-chek , with

1349-445: Is commonly believed that the dimorphisms found in raptors occur due to sexual selection or environmental factors. In general, hypotheses in favor of ecological factors being the cause for sexual dimorphism in raptors are rejected. This is because the ecological model is less parsimonious , meaning that its explanation is more complex than that of the sexual selection model. Additionally, ecological models are much harder to test because

1420-469: Is derived from the Ancient Greek kirkos , referring to a bird of prey named for its circling flight ( kirkos , "circle"). The specific epithet cyaneus is from Latin and means "dark blue". The species is monotypic : no subspecies are recognised. The hen harrier was formerly considered to be conspecific with the northern harrier . The hen harrier is 41–52 cm (16–20 in) long with

1491-516: Is derived from the Latin word rapio , meaning "to seize or take by force". The common names for various birds of prey are based on structure, but many of the traditional names do not reflect the evolutionary relationships between the groups. Many of these English language group names originally referred to particular species encountered in Britain . As English-speaking people travelled further,

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1562-453: Is important to quantify this pigmentation For the same reason, later eggs in a clutch are more spotted than early ones, as the female's store of calcium is depleted. Birds which build in trees generally have blue or greenish eggs, either spotted or unspotted, while birds that build in bushes or near or on the ground are likely to lay speckled eggs. The color of individual eggs is also genetically influenced, and appears to be inherited through

1633-411: Is merely the product of disruptive selection , and is merely a stepping stone in the process of speciation, especially if the traits that define gender are independent across a species. Sexual dimorphism can be viewed as something that can accelerate the rate of speciation. In non-predatory birds, males are typically larger than females. However, in birds of prey, the opposite is the case. For instance,

1704-421: Is necessary, and some parasitic cuckoos , which lay eggs that often closely match the passerine host's egg. To varying degrees of success, host passerine species have combined speckles, blotches and other egg markings with visual pattern-recognition abilities to help them reject cuckoos' counterfeit eggs. Most other passerines, in contrast, lay colored eggs, even if there is no need of cryptic colors. However,

1775-593: Is not believed to be approaching the thresholds for the population decline criterion of the IUCN Red List (i.e., declining more than 30% in ten years or three generations). It is therefore classified as "least concern". In Britain and Ireland, however, hen harrier populations are in a critical condition, due to habitat loss and illegal killing on grouse moors . In England alone there is enough suitable habitat for over 300 pairs of breeding Hen Harriers but in 2022 there were only 34 successful nests. Furthermore, many of

1846-535: Is usually within a small range of variation. Some birds respond to the accidental loss of eggs by laying a replacement egg. Others will stop laying based on the apparent size of the clutch. According to whether they respond to addition, removal, or both addition and removal of eggs, birds are classified as determinate layers (number of eggs laid is predetermined and do not respond to change) or as indeterminate layers. In general, birds with small clutch size tended to be indeterminate. Many animals feed on eggs. For example,

1917-502: The calcium carbonate from which the shells are made, but some birds, mainly passerines , produce colored eggs. The pigments biliverdin and its zinc chelate give a green or blue ground color, and protoporphyrin produces reds and browns as a ground color or as spotting. Non-passerines typically have white eggs, except in some ground-nesting groups, such as the Charadriiformes , sandgrouse and nightjars , where camouflage

1988-497: The kestrel is a type of falcon in which males are the primary providers, and the females are responsible for nurturing the young. In this species, the smaller the kestrels are, the less food is needed and thus, they can survive in environments that are harsher. This is particularly true in the male kestrels. It has become more energetically favorable for male kestrels to remain smaller than their female counterparts because smaller males have an agility advantage when it comes to defending

2059-422: The little bee-eater ) to highly pyriform or conical (such as those of the common murre ) with the familiar shape of the chicken egg lying in between. Early scientific investigators of egg shape suggested that the oval shape of eggs was caused by the egg being forced through the oviduct by peristalsis . In this often-repeated but incorrect theory of egg shape formation, the contraction and relaxation of

2130-641: The merlin ( Falco columbarius ). The taxonomy of Carl Linnaeus grouped birds (class Aves) into orders, genera, and species, with no formal ranks between genus and order. He placed all birds of prey into a single order, Accipitres , subdividing this into four genera: Vultur (vultures), Falco (eagles, hawks, falcons, etc.), Strix (owls), and Lanius (shrikes). This approach was followed by subsequent authors such as Gmelin , Latham and Turton . Louis Pierre Vieillot used additional ranks: order, tribe, family, genus, species. Birds of prey (order Accipitres) were divided into diurnal and nocturnal tribes;

2201-475: The Haast's eagle, implying that they similarly could pose a threat to a human being. Birds of prey have incredible vision and rely heavily on it for a number of tasks. They utilize their high visual acuity to obtain food, navigate their surroundings, distinguish and flee from predators, mating, nest construction, and much more. They accomplish these tasks with a large eye in relation to their skull, which allows for

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2272-554: The Swedish naturalist Carl Linnaeus updated his Systema Naturae for the twelfth edition , he placed the hen harrier with the falcons and eagles in the genus Falco . Linnaeus included a brief description, coined the binomial name Falco cyaneus and cited Edwards' work. The hen harrier is now placed in the genus Circus that was introduced by the French naturalist Bernard Germain de Lacépède in 1799. The genus name Circus

2343-489: The accipitrid species. The phylogeny of Accipitriformes is complex and difficult to unravel. Widespread paraphylies were observed in many phylogenetic studies. More recent and detailed studies show similar results. However, according to the findings of a 2014 study, the sister relationship between larger clades of Accipitriformes was well supported (e.g. relationship of Harpagus kites to buzzards and sea eagles and these latter two with Accipiter hawks are sister taxa of

2414-465: The big end tipped upward. The big end contains the air sac and its shell is pierced by a higher density of pores than the more pointed end. Tipping the big end upwards improves oxygen flow to the large head, with the physiologically demanding eyes and brain, that develops in the big end while the tail develops at the more pointed end. In a 2017 publication in the journal Science , mathematical modeling of 50,000 bird eggs data showed that bird egg shape

2485-697: The bills of birds of prey shown by hunters. In Britain, kites and buzzards were seen as destroyers of game and killed, for instance in 1684–5 alone as many as 100 kites were killed. Rewards for their killing were also in force in the Netherlands from 1756. From 1705 to 1800, it has been estimated that 624087 birds of prey were killed in a part of Germany that included Hannover, Luneburg, Lauenburg and Bremen with 14125 claws deposited just in 1796–97. Many species also develop lead poisoning after accidental consumption of lead shot when feeding on animals that had been shot by hunters. Lead pellets from direct shooting that

2556-531: The biogeographic realms of the Southern Hemisphere. The appearance of migratory behaviour occurred in the tropics parallel with the range expansion of migratory species to temperate habitats. Similar results of southern origin in other taxonomic groups can be found in the literature. Distribution and biogeographic history highly determine the origin of migration in birds of prey. Based on some comparative analyses, diet breadth also has an effect on

2627-436: The bird closely hugs the contours of the land below it. Northern or hen harriers hunt primarily small mammals , as do most harriers. Up to 95% of the diet comprises small mammals. However, birds are hunted with some regularity as well, especially by males. Preferred avian prey include passerines of open country (i.e. sparrows , larks , pipits ), small shorebirds and the young of waterfowl and galliforms . Supplementing

2698-422: The bird oviduct, see here ). However, this theory has been refuted by studies of egg shell formation in a number of bird species using techniques such as X-ray photography which have demonstrated that egg shape is determined in the oviduct isthmus (before shell calcification) with the pointed end caudal (furthest down the oviduct). These observations cannot be explained by peristalsis. It has been proposed that

2769-586: The birds have escaped from also cause reduced fitness and premature deaths. Some evidence supports the contention that the African crowned eagle occasionally views human children as prey, with a witness account of one attack (in which the victim, a seven-year-old boy, survived and the eagle was killed), and the discovery of part of a human child skull in a nest. This would make it the only living bird known to prey on humans, although other birds such as ostriches and cassowaries have killed humans in self-defense and

2840-468: The chicks. The male will help feed chicks after they hatch, but does not usually watch them for a greater period of time than around 5 minutes. The male usually passes off food to the female, which she then feeds to the young, although later the female will capture food and simply drop into the nest for her nestlings to eat. The chicks fledge at around 36 days old, though breeding maturity is not reached until 2 years in females and 3 years in males. In winter,

2911-523: The clade containing Aquilinae and Harpiinae). The diurnal birds of prey are formally classified into six families of two different orders (Accipitriformes and Falconiformes). These families were traditionally grouped together in a single order Falconiformes but are now split into two orders, the Falconiformes and Accipitriformes . The Cathartidae are sometimes placed in a separate order Cathartiformes . Formerly, they were sometimes placed in

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2982-409: The commercial growth cycle. Where forests replace habitats that were used by hen harriers they will therefore tend to reduce overall habitat availability. However, where afforestation takes place in areas that were previously underutilised by hen harriers, it may increase the value of such areas to this species in the long-term. Areas dominated by forestry may remain suitable to hen harriers provided that

3053-635: The diet occasionally are amphibians (especially frogs ), reptiles and insects (especially orthopterans ). The species has been observed to hunt bats if these are available. Larger prey, such as rabbits and adult ducks are taken sometimes and harriers have been known to subdue these by drowning them in water. Harriers hunt by surprising prey while flying low to the ground in open areas, as they drift low over fields and moors. The harriers circle an area several times listening and looking for prey. Harriers use hearing regularly to find prey, as they have exceptionally good hearing for diurnal raptors, this being

3124-525: The egg acquires its shape (with the pointed egg caudal) as it is forced through the narrow isthmus, but this assertion has not been thoroughly verified. Cliff-nesting birds often have highly conical eggs. They are less likely to roll off, tending instead to roll around in a tight circle; this trait is likely to have arisen due to evolution via natural selection. In contrast, many hole-nesting birds have nearly spherical eggs. The shape has biological significance. A pointed egg will tend to sit on its side, with

3195-439: The evolution of migratory behaviour in this group, but its relevance needs further investigation. The evolution of migration in animals seems to be a complex and difficult topic with many unanswered questions. A recent study discovered new connections between migration and the ecology, life history of raptors. A brief overview from abstract of the published paper shows that "clutch size and hunting strategies have been proved to be

3266-471: The existing literature combining anatomical, genetic, and behavioural studies showed that, in general, raptors have functional olfactory systems that they are likely to use in a range of different contexts. Birds of prey have been historically persecuted both directly and indirectly. In the Danish Faroe Islands , there were rewards Naebbetold (by royal decree from 1741) given in return for

3337-493: The familiar names were applied to new birds with similar characteristics. Names that have generalised this way include: kite ( Milvus milvus ), sparrowhawk or sparhawk ( Accipiter nisus ), goshawk ( Accipiter gentilis ), kestrel ( Falco tinninculus ), hobby ( Falco subbuteo ), harrier (simplified from "hen-harrier", Circus cyaneus ), buzzard ( Buteo buteo ). Some names have not generalised, and refer to single species (or groups of closely related (sub)species), such as

3408-463: The few raptorial birds known to practice polygyny – one male mates with several females. Up to five females have been known to mate with one male in a season. A supplementary feeding experiment on the Orkney islands showed that rates of polygyny were influenced by food levels; males provided with extra food had more breeding females than 'control' males that received no extra food. The nest is built on

3479-616: The function of their owl -like facial disc. This harrier tends to be a very vocal bird while it glides over its hunting ground. Little information is available on longevity in hen harriers. The longest-lived known bird is 16 years and 5 months. However, adults rarely live more than 8 years. Early mortality mainly results from predation. Predators of eggs and nestlings include raccoons , skunks , badgers , foxes , crows and ravens , dogs and owls . Both parents attack potential predators with alarm calls and striking with talons. Short-eared owls are natural competitors of this species that favor

3550-434: The ground or on a mound of dirt or vegetation. Nests are made of sticks and are lined inside with grass and leaves. Four to eight (exceptionally 2 to 10) whitish eggs are laid. The eggs measure approximately 47 mm × 36 mm (1.9 in × 1.4 in). The eggs are incubated mostly by the female for 31 to 32 days. When incubating eggs, the female sits on the nest while the male hunts and brings food to her and

3621-452: The hen harrier is a bird of open country, and will then roost communally, often with merlins and marsh harriers . There is now an accepted record of transatlantic vagrancy by the northern harrier, with a juvenile being recorded in Scilly , Great Britain from October 1982 to June 1983. This is a typical harrier, which hunts on long wings held in a shallow V in its low flight during which

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3692-501: The higher ground is largely deserted in winter. The northern harrier was formerly considered to be a subspecies of the hen harrier. In 1758 the English naturalist George Edwards included an illustration and a description of the hen harrier in the first volume of his Gleanings of Natural History . He used the English name "The blue hawk". Edwards based his hand-coloured etching on a bird that had been shot near London. When in 1766

3763-400: The highest density of photoreceptors, and provide the highest points of visual acuity. The deep fovea points forward at an approximate 45° angle, while the shallow fovea points approximately 15° to the right or left of the head axis. Several raptor species repeatedly cock their heads into three distinct positions while observing an object. First, is straight ahead with their head pointed towards

3834-407: The highly acute deep fovea. Like all birds, raptors possess tetrachromacy , however, due to their emphasis on visual acuity, many diurnal birds of prey have little ability to see ultraviolet light as this produces chromatic aberration which decreases the clarity of vision. Bird egg All bird eggs contain the following components: The default color of vertebrate eggs is the white of

3905-603: The most important variables in shaping distribution areas, and also the geographic dissimilarities may mask important relationships between life history traits and migratory behaviours. The West Palearctic-Afrotropical and the North-South American migratory systems are fundamentally different from the East Palearctic-Indomalayan system, owing to the presence versus absence of ecological barriers." Maximum entropy modelling can help in answering

3976-408: The mother only, suggesting the gene responsible for pigmentation is on the female-specific W chromosome (female birds are WZ, males are ZZ). Color was once thought to be applied to the shell immediately before laying, but this research shows coloration is an integral part of the development of the shell, with the same protein responsible for depositing calcium carbonate, or protoporphyrins when there

4047-401: The muscles which push the egg down the oviduct cause the spherical egg membrane to distort slightly into an ovoid shape, with the blunt end caudal (i.e. furthest down the oviduct and closest to the cloaca ). The calcification of the egg in the shell gland/ uterus then fixes it in this shape, and the egg is laid with the blunt end appearing first (for a diagram showing the different sections of

4118-821: The narrower definition followed in this page, excluding many piscivorous predators such as storks , cranes , herons , gulls , skuas , penguins , and kingfishers , as well as many primarily insectivorous birds such as passerines (e.g. shrikes ), nightjars , frogmouths , songbirds such as crows and ravens , alongside opportunistic predators from predominantly frugivorous or herbivorous ratites such as cassowaries and rheas . Some extinct predatory telluravian birds had talons similar to those of modern birds of prey, including mousebird relatives ( Sandcoleidae ), and Messelasturidae indicating possible common descent . Some Enantiornithes also had such talons, indicating possible convergent evolution , as enanthiornithines weren't even modern birds . The term raptor

4189-444: The nest and hunting. Larger females are favored because they can incubate larger numbers of offspring, while also being able to brood a larger clutch size. It is a long-standing belief that birds lack any sense of smell, but it has become clear that many birds do have functional olfactory systems . Despite this, most raptors are still considered to primarily rely on vision, with raptor vision being extensively studied. A 2020 review of

4260-629: The object. Second and third are sideways to the right or left of the object, with their head axis positioned approximately 40° adjacent to the object. This movement is believed to be associated with lining up the incoming image to fall on the deep fovea. Raptors will choose which head position to use depending on the distance to the object. At distances as close as 8m, they used primarily binocular vision. At distances greater than 21m, they spent more time using monocular vision. At distances greater than 40m, they spent 80% or more time using their monocular vision. This suggests that raptors tilt their head to rely on

4331-470: The oldest dates published so far in the case of birds of prey. For example, a previous reconstruction of migratory behaviour in one Buteo clade with a result of the origin of migration around 5 million years ago was also supported by that study. Migratory species of raptors may have had a southern origin because it seems that all of the major lineages within Accipitridae had an origin in one of

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4402-412: The order Ciconiiformes . The secretary bird and/or osprey are sometimes listed as subfamilies of Acciptridae: Sagittariinae and Pandioninae, respectively. Australia's letter-winged kite is a member of the family Accipitridae , although it is a nocturnal bird. The nocturnal birds of prey—the owls —are classified separately as members of two extant families of the order Strigiformes : Below

4473-503: The order Gruiformes . And they are still not considered birds of prey in general parlance. Their bodies are also shaped completely differently from birds of prey. They have long legs and long necks. While secretarybirds also have long legs, they otherwise resemble raptors. Seriemas do not. Their beak is hooked, but too long. Migratory behaviour evolved multiple times within accipitrid raptors. The earliest event occurred nearly 14 to 12 million years ago. This result seems to be one of

4544-813: The owls remained monogeneric (family Ægolii, genus Strix ), whilst the diurnal raptors were divided into three families: Vulturini, Gypaëti, and Accipitrini. Thus Vieillot's families were similar to the Linnaean genera, with the difference that shrikes were no longer included amongst the birds of prey. In addition to the original Vultur and Falco (now reduced in scope), Vieillot adopted four genera from Savigny: Phene , Haliæetus , Pandion , and Elanus . He also introduced five new genera of vultures ( Gypagus , Catharista , Daptrius , Ibycter , Polyborus ) and eleven new genera of accipitrines ( Aquila , Circaëtus , Circus , Buteo , Milvus , Ictinia , Physeta , Harpia , Spizaëtus , Asturina , Sparvius ). Falconimorphae

4615-444: The photographic markings on passerine eggs have been suggested to reduce brittleness by acting as a solid state lubricant. If insufficient calcium is available in the local soil, the egg shell may be thin, especially in a circle around the broad end. Protoporphyrin speckling compensates for this, and increases inversely to the amount of calcium in the soil. To understand the functional significance of eggshell spotting (or maculation) it

4686-833: The placement of the birds of prey. Their analysis has found support in a clade consisting of the Strigiformes and Accipitriformes in new clade Hieraves . Hieraves was also recovered to be the sister clade to Australaves (which it includes the Cariamiformes and Falconiformes along with Psittacopasserae ). Below is their phylogeny from the study. Coraciimorphae (woodpeckers, rollers, hornbills, etc.) [REDACTED] Strigiformes (owls) [REDACTED] Accipitriformes (hawks, vultures, and relatives) [REDACTED] Cariamiformes (seriemas) [REDACTED] Falconiformes (falcons) [REDACTED] Psittacopasserae (parrots and songbirds) [REDACTED] Cariamiformes

4757-455: The principal predators of the black oystercatcher 's eggs include raccoons , skunks , mink , river and sea otters , gulls , crows and foxes . The stoat ( Mustela erminea ) and long-tailed weasel ( Neogale frenata ) steal ducks' eggs. Ostrich eggs are vulnerable to many predators ranging from mongooses and Egyptian vultures , to hyenas . Snakes of the genera Dasypeltis and Elachistodon specialize in eating eggs. Humans have

4828-464: The question: why species winters at one location while the others are elsewhere. Temperature and precipitation related factors differ in the limitation of species distributions. "This suggests that the migratory behaviours differ among the three main migratory routes for these species" which may have important conservational consequences in the protection of migratory raptors. Birds of prey (raptors) are known to display patterns of sexual dimorphism . It

4899-407: The same prey and habitat, as well as having a similarly broad distribution. Occasionally, both harriers and short-eared owls will harass each other until the victim drops its prey and it can be stolen, a practice known as kleptoparasitism . Most commonly, the harriers are the aggressors pirating prey from owls. This species has a large range. There is evidence of a population decline, but the species

4970-420: The size of the adult bird, from the half gram egg of the bee hummingbird to the 1.5 kg egg of the ostrich . Kiwis have disproportionately large eggs, up to 20% of the female's body weight. This evolutionary trait results in kiwi chicks that can emerge from the nest days after hatching, ready to start foraging for food. The number of eggs laid in a single brood is referred to as the clutch. Clutch size

5041-682: The young birds don’t even make it through their first year, let alone survive until the age of two, when they can first breed. Most UK Hen Harriers are in Scotland but even there its population declined by 27% between 2004 and 2016. In some parts of Europe people believed that seeing a harrier perched on a house was a sign that three people would die. Unlike many raptors, hen harriers have historically been seen favorably by farmers because they eat predators of quail eggs and mice that damage crops. Harriers are sometimes called "good hawks" because they pose no threat to poultry as some hawks do. The hen harrier

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