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    شاهین


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    (Wikipedia) - Hawk For other uses, see hawk (disambiguation) and hawks (disambiguation).Sharp-shinned hawk

    Hawk is a common name for some small to medium-sized diurnal birds of prey, widely distributed and varying greatly in size.

    The terms buteonine hawk and accipitrine hawk may be used to distinguish the two types, in regions where hawk applies to both. The term "true hawk" (with scare quotes) is sometimes used for the accipitrine hawks, in regions where buzzard is preferred for the buteonine hawks.

    All these groups are members of the Accipitridae family, which includes the hawks and buzzards as well as kites, harriers and eagles.

    Some authors use "hawk" generally for any small to medium Accipitrid that is not an eagle.

    Immature Northern goshawk with fresh killHawk sighted in Toronto in front of the Fields Institute.

    The common names of some birds include the term "hawk", reflecting traditional usage rather than taxonomy, such as referring to an osprey as a "fish hawk" or a peregrine falcon as a "duck hawk".

    Contents

    History

    Falconry was also called "hawking", and any bird used for falconry could be referred to as a hawk.

    Groups Accipiter group

    The accipitrine hawks generally take birds as their primary prey. They have also been called "hen-hawks", or "wood-hawks" because of their woodland habitat.

    The subfamily Accipitrinae contains Accipiter; it also contains genera Micronisus (Gabar goshawk), Urotriorchis (long-tailed hawk), and Megatriorchis (Doria''s goshawk). Melierax (chanting goshawks) may be included in the subfamily, or given a subfamily of its own.

    Erythrotriorchis (the red and chestnut-shouldered goshawks) is traditionally included in Accipitrinae, but is possibly a convergent genus from an unrelated group (see red goshawk taxonomy).

    Buteo group

    The "Buteo group" includes genera Buteo, Parabuteo, Geranoetus, and most of Leucopternis.

    Members of this group have also been called "hawk-buzzards".

    Proposed new genera Morphnarchus, Rupornis, and Pseudastur are formed from members of Buteo and Leucopternis.

    The "Buteogallus group" are also called hawks, with the exception of the solitary eagles.

    Buteo is the type genus of the subfamily Buteoninae. Traditionally this subfamily also includes eagles and sea-eagles. Lerner and Mindell (2005) proposed placing those into separate subfamilies (Aquilinae, Haliaaetinae), leaving just the buteonine hawks/buzzards in Buteoninae.

    Characteristics
    This section requires expansion. (September 2012)
    Intelligence

    In February 2005, the Canadian ornithologist Louis Lefebvre announced a method of measuring avian "IQ" in terms of their innovation in feeding habits. Hawks were named among the most intelligent birds based on his scale.

    Eyesight

    Hawks have four types of colour receptors in the eye. These give birds the ability to perceive not only the visible range but also the ultraviolet part of the spectrum, and other adaptations allow for the detection of polarised light or magnetic fields. This is due to the many photoreceptors in the retina (up to 1,000,000 per square mm for Buteo, against 200,000 for humans), an exceptional number of nerves connecting these receptors to the brain, and an indented fovea, which magnifies the central portion of the visual field.

    Description

    Hawks have always been known to have sharp vision and to be very able hunters. Within the hawk species, the female is generally larger than the male.

    Migration

    Like most birds, the hawk migrates in the autumn and the spring. Different types of hawks choose separate times in both of the seasons to migrate north or south. The entire autumn migrating season extends all the way from August to half way through December. It has been studied that there are longer migration distances than others. The long-distance travelers tend to begin in early autumn while the short distance travelers start much later. Thus, the longer the distance the earlier the bird begins its journey. There have also been a few studies on the relevance of the speed and efficiency of the bird''s migration. It is better for a hawk to arrive at its destination as early as possible. This is because the first bird to a new area has the first pick of mates, living area, food, and much more necessities for survival. The more fat a bird has when it starts its migration, the better chance it has of making the trip safely. Kerlinger states that studies have shown that a bird has more body fat when it begins its migration, before it leaves, than when it is finished with its travels and has arrived at its destination.

    One of the most important parts of the hawk''s migration is the flight direction because the direction or path the bird chooses to take could greatly affect its migration. The force of wind is a large variable because it could either throw the bird off course or push it in the right direction, depending on the direction of the wind. To ensure a safer journey, a hawk tries to avoid any large bodies of water in the spring and fall by detouring around a lake or flying along a border.

    Habitat and distribution

    Tags:Canadian, Sharp, Toronto, Wikipedia


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