Editing Cooper's hawk (section)

===Size===
Cooper's hawks are fairly variable in size. There is usually minimal to no overlap in dimensions between the sexes, with females being considerably larger than males.<ref name= Palmer/> On average, she may be about 20% larger linearly and around 40% heavier (though can be up to 125% more massive).<ref name= Ferguson-Lees/> More westerly Cooper's hawks (roughly west of the [[Rocky mountains]]) show slightly less pronounced [[sexual dimorphism]] than hawks of the species elsewhere.<ref name= Smith>Smith, J. P., Hoffman, S. W., & Gessaman, J. A. (1990). ''Regional Size Differences among Fall-Migrant Accipiters in North America''. Journal of Field Ornithology, 192–200.</ref> 

Sexual dimorphism in Cooper's hawks is most reliably measured by wing size, talon size, then body mass. Although there is some margin of error, within a given region dimensions of the two sexes never overlap in these regards (but may overlap marginally in tarsal and tail lengths).<ref name="Hoffman" /> In general terms, ''Accipiter'' species are among the most sexually dimorphic in size of all raptorial birds.<ref name="Reynolds">{{Cite journal | last=Reynolds | first=Richard T. | date=1972 | title=Sexual dimorphism in ''Accipiter'' hawks: A new hypothesis | journal=The Condor | volume=74 | issue=2 | pages=191-197 | doi=10.2307/1366283 | url=https://sora.unm.edu/node/102162 }}</ref> Sexual dimorphism in ''Accipiters'' may be due to greater male efficiency through smaller size and resulting agility in food gathering for the family group. Meanwhile, the female may be better suited to the rigors of brooding (including perhaps most nest defense) due to her larger size, also allowing the sexes to compete less on the same food sources.<ref name="Snyder" /><ref name="Reynolds" /> 

Geographic variation in body size has also been found, with more easterly hawks tending to be rather larger on average than those found in western North America.<ref name="umich2000">Dewey, T. and V. Perepelyuk. (2000). [http://animaldiversity.ummz.umich.edu/site/accounts/information/Accipiter_cooperii.html ''Accipiter cooperii''], Animal Diversity Web. Accessed April 22, 2010.</ref><ref name="Mueller">Mueller, H. C., & Berger, D. D. (1981). ''Age, sex, and seasonal differences in size of Cooper's Hawks''. Journal of Field Ornithology, 52(2), 112–126.</ref> On the contrary, in the [[Southwestern United States|American southwest]], the species may reportedly reach its largest sizes but there is little evidence that these birds average distinctly larger than the large bodied individuals measured in the more northeasterly parts of the species' range in North America, from eastern [[North Dakota]] to [[New Jersey]].<ref name=BOW /><ref name="Whaley">Whaley, W. H., & White, C. M. (1994). ''Trends in geographic variation of Cooper's hawk and northern goshawk in North America: a multivariate analysis''. Western Foundation of Vertebrate Zoology.</ref> The size variation evidenced in Cooper's hawks is apparently the most pronounced of any of the three North American species of ''Accipiter''.<ref name="Smith" /> However, Cooper's hawks are one of an estimated 25% of studied bird species that do not appear to correspond to [[Bergmann's rule]] (i.e. being larger where living farther north) instead varying in size much more so by [[longitude]].<ref>Meiri, S., & Dayan, T. (2003). ''On the validity of Bergmann's rule''. Journal of biogeography, 30(3), 331–351.</ref> Furthermore, juveniles can differ somewhat in size, tending to be slightly lighter and smaller than older birds, but not infrequently averaging longer in tail and especially wing length.<ref name="Mueller" /><ref name="Rosenfield3">Rosenfield, R. N., Rosenfield, L. J., Bielefeldt, J., Murphy, R. K., Stewart, A. C., Stout, W. E., Driscoll, T.G. & Bozek, M. A. (2010). ''Comparative morphology of northern populations of breeding Cooper's Hawks''. The Condor, 112(2), 347–355.</ref> Total length of full-grown birds can vary from {{convert|35|to|46|cm|in|abbr=on}} in males and {{convert|42|to|50|cm|in|abbr=on}} in females.<ref name="Palmer" /><ref name="umich2000" /><ref name="allaboutbirds1" /> Wingspan may range from {{convert|62|to|99|cm|in|abbr=on}}, with an average of around {{convert|84|cm|in|abbr=on}}.<ref name="Palmer" /><ref name="HBW">White, C.M., Boesman, P. & Marks, J.S. (2020). ''Cooper's Hawk (Accipiter cooperii)''. In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona.</ref><ref name="Cartron">Cartron, J. L. E. (Ed.). (2010). ''Raptors of New Mexico''. UNM Press.</ref>
 
[[File:Hawk (28346062734).jpg|thumb|An adult Cooper's hawk illustrates its mid-sized frame and very long tail]]
Body mass, along with standard measurements, is much more frequently measured than total length or wingspan in different populations.<ref name= Palmer/> Museum specimens from the western United States averaged {{convert|280|g|oz|abbr=on}} in 48 males and {{convert|473|g|lb|abbr=on}} in 20 females, while those sourced from the eastern United States averaged {{convert|338|g|oz|abbr=on}} in 16 males and {{convert|566|g|lb|abbr=on}} in 31 females.<ref name= Friedmann>Friedmann, H. (1950). ''Birds of North and Middle America, Part 2''. U.S. National Museum Bulletin no. 50.</ref> Average weight of 104 male migrating hawks in [[Cedar Grove, Wisconsin]] was {{convert|342|g|oz|abbr=on}} (with adults averaging 4% heavier than juveniles), whilst the average of 115 females migrants was {{convert|518|g|lb|abbr=on}} (with adult averaging about 5.5% heavier than juveniles).<ref name= Mueller/> A different sample of Wisconsin Cooper's hawks reportedly averaged {{convert|327|g|oz|abbr=on}} in males (sample size 60) and {{convert|580.3|g|lb|abbr=on}} in females (sample size 57).<ref name= Rosenfield3/> At [[Cape May Point]], [[New Jersey]], weights were similar as in Wisconsin (although only hatching-year juveniles were apparently weighed), with averages of {{convert|339.2|and|347|g|oz|abbr=on}} in two samples of males and {{convert|518|and|530.3|g|lb|abbr=on}} in the two samples for females.<ref name= Pearlstine/><ref name= Smith/> Migrant hawks in the [[Goshute Mountains]] of [[Nevada]] were significantly lighter than the eastern ones at {{convert|269|g|oz|abbr=on}} in 183 first year males and {{convert|281|g|oz|abbr=on}} in 177 older males and {{convert|399|g|oz|abbr=on}} in 310 first year females and {{convert|439|g|oz|abbr=on}} in 416 older females.<ref name= Smith/> Weights were similar to the Goshutes in the [[Marin Headlands]], California where 50 males (all first-years) averaged {{convert|288|g|oz|abbr=on}} and 117 first-year females averaged {{convert|417|g|oz|abbr=on}}.<ref name= Smith/><ref name= Pitzer>Pitzer, S., Hull, J., Ernest, H. B., & Hull, A. C. (2008). ''Sex determination of three raptor species using morphology and molecular techniques''. Journal of Field Ornithology, 79(1), 71–79.</ref> Averaged between early and late summer, the average mass of males in [[Oregon]] was {{convert|280.7|g|oz|abbr=on}} and that of females was reported at {{convert|488.4|g|lb|abbr=on}}.<ref name= Henny/> The average weights of Cooper's hawks from Oregon was about 19.4% lower in males and 14.5% lower in females than those from Wisconsin but the Oregon hawks evidenced less seasonal variation in weight.<ref name= Henny/> In [[British Columbia]], males averaged {{convert|295.8|g|oz|abbr=on}} and females averaged {{convert|525.5|g|lb|abbr=on}} while in western and eastern North Dakota, males averaged {{convert|301.5|and|318.7|g|oz|abbr=on}} and females averaged {{convert|514.3|and|563.3|g|lb|abbr=on}}.<ref name= BOW/><ref name= Rosenfield3/> In northern Florida, males averaged {{convert|288|g|oz|abbr=on}} and females averaged {{convert|523|g|lb|abbr=on}}.<ref name= Millsap>Millsap, B. A., Breen, T. F., & Phillips, L. M. (2013). ''Ecology of the Cooper's Hawk in north Florida''. North American Fauna, 78(00), 1–58.</ref> In general, males may weigh anywhere from {{convert|215|to|390|g|oz|abbr=on}} and females anywhere from {{convert|305.8|to|701|g|lb|abbr=on}}, the lightest hawks generally being juveniles recorded from the Goshutes of Nevada, the heaviest known being adults from Wisconsin.<ref name= Hoffman>Hoffman, S. W., Smith, J. P., & Gessaman, J. A. (1990). ''Size of Fall-Migrant Accipiters from the Goshute Mountains of Nevada (Tamaño de migrantes otoñales (Accipitrinae) de las Montañas Goshute, Nevada)''. Journal of Field Ornithology, 201–211.</ref><ref name= Rosenfield4>Rosenfield, R. N., Bielefeldt, J., Haynes, T. G., Hardin, M. G., Glassen, F. J., & Booms, T. L. (2016). ''Body mass of female Cooper's Hawks is unrelated to longevity and breeding dispersal: Implications for the study of breeding dispersal''. Journal of Raptor Research, 50(3), 305–312.</ref>

Among standard measurements, the [[Wing chord (biology)|wing chord]] may vary from {{convert|214|to|252|mm|in|abbr=on}} in males and from {{convert|247|to|278|mm|in|abbr=on}} in females.<ref name= Ferguson-Lees/><ref name= Rosenfield5>Rosenfield, L. J. (2006). ''Comparative morphology among three northern populations of breeding Cooper's Hawks'' (Doctoral dissertation, University of Wisconsin—Stevens Point).</ref> Wing chord is generally commensurate with body mass, averaging largest in the heavier hawks of eastern North Dakota, where males averaged {{convert|232.6|mm|in|abbr=on}} and females {{convert|264.3|mm|in|abbr=on}}, and in Wisconsin, where males averaged {{convert|236.9|mm|in|abbr=on}} and females {{convert|267.1|mm|in|abbr=on}} (those from Cape May also being similar to those two samples). However, smaller, more westerly hawks such as those in the Goshute mountains, where males measured at a mean of {{convert|224.1|mm|in|abbr=on}} and females at a mean of {{convert|254.8|mm|in|abbr=on}}, and in British Columbia, with a male mean of {{convert|227|mm|in|abbr=on}} and female mean of {{convert|256.8|mm|in|abbr=on}}, were proportionately longer winged relative to their other body proportions.<ref name= BOW/><ref name= Rosenfield3/><ref name= Hoffman/> The tail of males may vary from {{convert|166|to|211|mm|in|abbr=on}} and that of females at {{convert|203|to|242|mm|in|abbr=on}}, consistently over {{convert|200|mm|in|abbr=on}} in females and averaging under {{convert|190|mm|in|abbr=on}} in males.<ref name= Ferguson-Lees/><ref name= Brown/><ref name= Hoffman/><ref name= Rosenfield5/> In [[Tibiotarsus|tarsus]] length, males may vary from {{convert|55.2|to|73|mm|in|abbr=on}}, with an average of {{convert|64.1|mm|in|abbr=on}} in museum specimens, and females from {{convert|62|to|76|mm|in|abbr=on}}, with an average of {{convert|71.1|mm|in|abbr=on}} in museum specimens.<ref name= Ferguson-Lees/><ref name= Friedmann/><ref name= Hoffman/><ref>{{cite web| url= http://www.royalbcmuseum.bc.ca/Natural_History/Bones/Tarsus/tarsus57.htm |title= ''Avian Osteology: Tarsometatarsus'' |website= RoyalBCMuseum.bc.ca| publisher= Royal British Columbia Museum Corporation | access-date= August 21, 2012}}</ref> The [[Beak|culmen]] may measure from {{convert|11.7|to|17.5|mm|in|abbr=on}} in males, averaging about {{convert|16|mm|in|abbr=on}}, and from {{convert|17.5|to|23|mm|in|abbr=on}} in females, averaging about {{convert|19|mm|in|abbr=on}}.<ref name= Friedmann/><ref name= Hoffman/><ref name= Rosenfield5/><ref>{{cite book| first1= Emmet Reid| last1= Blake |title=''Manual of Neotropical Birds'' |url=https://books.google.com/books?id=YP0AX3LW8jYC&pg=PA301 |access-date=August 21, 2012 |date=July 1, 1977 |publisher= University of Chicago Press |isbn=978-0-226-05641-8 |pages=301–}}</ref> The [[Claw|hallux claw]], the enlarged rear talon featured on nearly all accipitrids, may measure from {{convert|17|to|21.7|mm|in|abbr=on}} in males, averaging about {{convert|19.2|mm|in|abbr=on}}, and from {{convert|19.8|to|26.7|mm|in|abbr=on}} in females, averaging about {{convert|23.3|mm|in|abbr=on}}.<ref name= Hoffman/><ref name= Rosenfield5/> The footpad of Cooper's hawks may measure in males {{convert|61|to|70.2|mm|in|abbr=on}}, averaging {{convert|66|mm|in|abbr=on}} in 42, and in females {{convert|74.1|to|83.5|mm|in|abbr=on}}, averaging {{convert|76.8|mm|in|abbr=on}} in 23.<ref name= Whaley/> For unclear reasons, the smaller-bodied hawks found in British Columbia were found to be proportionately larger footed, median toe length between sexes of {{convert|37.3|mm|in|abbr=on}}, than the larger bodied ones in Wisconsin.<ref name= Feet>Rosenfield, R. N., Stewart, A. C., Stout, W. E., Sonsthagen, S. A., & Frater, P. N. (2020). ''Do British Columbia Cooper's Hawks Have Big Feet?'' British Columbia Birds, 30.</ref>