Editing Accipitridae (section)

== Morphology ==
[[File:Bald.eagle.closeup.arp-sh.750pix.jpg|thumb|left|Portrait of a subadult [[bald eagle]], showing its strongly hooked beak and the cere covering the base of the beak]]

The Accipitridae are a diverse family with a great deal of variation in size and shape. They range in size from the tiny [[pearl kite]] (''Gampsonyx swainsonii'') and [[little sparrowhawk]] (''Accipiter minullus''), both of which are 23&nbsp;cm (9&nbsp;in) in length and weigh about 85 g (3&nbsp;oz), to the [[cinereous vulture]] (''Aegypius monachus''), which measures up to 120&nbsp;cm (47&nbsp;in) and weighs up to 14&nbsp;kg (31&nbsp;lbs). Wingspan can vary from {{convert|39|cm|in|abbr=on}} in the little sparrowhawk to more than {{convert|300|cm|in|abbr=on}} in the cinereous and [[Himalayan vulture]]s (''Gyps himalayensis''). In these extreme species, [[Wing chord (biology)|wing chord]] length can range from {{convert|113|to|890|mm|in|abbr=on}} and [[Culmen (bird)|culmen]] length from {{convert|11|to|88|mm|in|abbr=on}}. Until the 14th century, even these huge vultures were surpassed by the [[extinction|extinct]] [[Haast's eagle]] (Hieraaetus ''moorei'') of New Zealand, which is estimated to have measured up to 140&nbsp;cm (55&nbsp;in) and to have weighed {{convert|15|to|16.5|kg|lb|abbr=on}} in the largest females.{{sfn|Brathwaite|1992}}<ref name= Worthy>Worthy, T. & Holdaway, R., ''The Lost World of the Moa: Prehistoric Life of New Zealand''. Indiana University Press (2003), {{ISBN|978-0253340344}}</ref> In terms of body mass, the Accipitridae are the most diverse family of birds and may also be in terms of some aspects of linear size diversity, although lag behind the [[true parrot]]s and [[Phasianidae|pheasant family]] in length diversity.{{sfn|Ferguson-Lees|Christie|2001|p=}} Most accipitrids exhibit [[sexual dimorphism]] in size, although, unusually for birds, it is the females that are larger than the males.{{sfn|Paton|Messina|Griffin|1994}} This sexual difference in size is most pronounced in active species that hunt birds, such as the ''[[Accipiter]]'' hawks, in which the size difference averages 25–50%. In a majority of species, such as generalist hunters and [[rodent]]-, [[reptile]]-, [[fish]]-, and [[insect]]-hunting specialists, the dimorphism is less, usually between a 5% to 30% size difference. In the carrion-eating [[Old World vulture]]s and snail eating [[Kite (bird)|kite]]s, the difference is largely non-existent, though sometimes the female may average slightly heavier.{{sfn|Ferguson-Lees|Christie|2001|p=}}

The beaks of accipitrids are strong and hooked (sometimes very hooked, as in the [[hook-billed kite]] or [[snail kite]]). In some species, there is a notch or 'tooth' in the upper mandible. In all accipitrids, the base of the upper mandible is covered by a fleshy membrane called the cere, which is usually yellow in colour. The [[Tarsus (skeleton)|tarsi]] of different species vary by diet; those of bird-hunting species, such as sparrowhawks, are long and thin, whilst species that hunt large mammals have much thicker, stronger tarsi, and the tarsi of the [[snake-eagle]]s have thick scales to protect from bites.

The [[plumage]] of the Accipitridae can be striking, but rarely utilises bright colours; most birds use combinations of white, grey, buff, brown and black.{{sfn|Thiollay|1994}} Overall they tend to be [[Countershading|paler below]], which helps them seem less conspicuous when seen from below. There is seldom sexual dimorphism in plumage, when it occurs the males are brighter or the females resemble juveniles. In many species juveniles have a distinctly different plumage. Some accipitrids [[mimicry|mimic]] the plumage patterns of other hawks and eagles. Resembling a less dangerous species may [[Aggressive mimicry|fool prey]]; resembling a more dangerous species may reduce [[Mobbing behavior|mobbing]] by other birds.{{sfn|Negro|2008}} Several species of accipitrid have crests used in signalling, and even species without crests can raise the [[feather]]s of the crown when alarmed or excited. In contrast most of the [[Old World vulture]]s possess bare heads without feathers; this is thought to prevent soiling on the feathers and aid in [[thermoregulation]].{{sfn|Ward|McCafferty|Houston|Ruxton|2008}}

The senses of the Accipitridae are adapted to hunting (or scavenging), and in particular their [[bird vision|vision]] is exceptional, with some large accipitrids such as the [[wedge-tailed eagle]] and Old World vultures having over twice the visual acuity of a typical human.<ref>{{Citation |last1=Mitkus |first1=Mindaugas |title=Raptor Vision |date=2018-04-26 |url=https://oxfordre.com/neuroscience/display/10.1093/acrefore/9780190264086.001.0001/acrefore-9780190264086-e-232 |encyclopedia=Oxford Research Encyclopedia of Neuroscience |access-date=2023-06-12 |language=en |doi=10.1093/acrefore/9780190264086.013.232 |isbn=978-0-19-026408-6 |last2=Potier |first2=Simon |last3=Martin |first3=Graham R. |last4=Duriez |first4=Olivier |last5=Kelber |first5=Almut }}</ref><ref>{{Cite journal |last=Martin |first=Graham R. |date=January 1986 |title=Vision: Shortcomings of an eagle's eye |journal=Nature |language=en |volume=319 |issue=6052 |pages=357 |doi=10.1038/319357a0 |pmid=3945316 |bibcode=1986Natur.319..357M |s2cid=4233018 |issn=1476-4687|doi-access=free }}</ref><ref>{{Cite journal |last=Reymond |first=L. |date=1985 |title=Spatial visual acuity of the eagle Aquila audax: a behavioural, optical and anatomical investigation |url=https://pubmed.ncbi.nlm.nih.gov/4090282/ |journal=Vision Research |volume=25 |issue=10 |pages=1477–1491 |doi=10.1016/0042-6989(85)90226-3 |issn=0042-6989 |pmid=4090282|s2cid=20680520 }}</ref> Large eyes with two [[Fovea centralis|foveae]] provide binocular vision and a "hawk eye" for movement and distance judging. In addition the Accipitridae have the largest [[pecten oculi|pectens]] of any birds. The eyes are tube shaped and cannot move much in their sockets. In addition to excellent vision many species have excellent hearing{{Citation needed|date=June 2023}}, but unlike in owls sight is generally the principal sense used for hunting. Hearing may be used to locate prey hidden in vegetation, but sight is still used to catch the prey. Although they rely primarily on vision, Accipitridae do have functioning [[olfactory system]]s, which they make use of in a variety of contexts.<ref>{{cite journal|author1=Potier, Simon|year=2020|title=Olfaction in raptors|journal=Zoological Journal of the Linnean Society|volume=189|issue=3|pages=713–721|url=https://academic.oup.com/zoolinnean/article/189/3/713/5601241|doi=10.1093/zoolinnean/zlz121|doi-access=free}}</ref>