Cast and Let Fly: A Kettle of Hawks

A kettle of red-tailed hawks (Buteo jamaicensis)
over San Francisco (photo courtesy of Jessica Weinberg,
Golden Gate National Recreation Area, NPS)

Hawks are birds of prey who every year migrate long distances north and south. Many gain ten to 20 percent of their body weight before undertaking the trip. The weight is stored as fat, a high-density fuel. As migration exacts a high energy cost, the birds need this extra fuel to complete their travels over thousands of miles. Hawks along with other birds of prey save as much energy as they can, much as cyclists will put their bikes in low gear when going up hill or refrain from pedaling at all on the way down. When a hawk finds a wind deflecting over a hill, the bird will ride it up-- this is called a slope soar. When a hawk finds a pocket of warm air rising from the ground (called a thermal), the bird will circle skyward, as high as 3000 feet (915 m), and then glide gently on its way. This is called a thermal soar.


As they travel, hawks may form a flock with other birds of prey-- falcons, goshawks, eagles. Birdwatchers seek out these low-energy thermal glides, watching as majestic wings rise slowly and then drift on. A sky full of gliding hawks and raptors is widely known in birding as a kettle. The terms boil and cauldron are also heard. In each case the term envisions hawks spinning up to their destination by the power of the warming earth. The terms kettle and cauldron are also used metaphorically for "hawks" on matters of public policy: CNBC reports on a "cauldron of hawks" that has emerged on the Federal Reserve's inflation policy; The Guardian reports on a so-called "kettle of hawks" on national security matters. Total online references to kettle outnumber references to both cauldron and boil by about 20 to one.


Orinthologist Donald Heintzelman has done more than anyone to popularize the term kettle. He used the term in print over the course of four decades beginning at least as early as 1970 in his book Hawks of New Jersey. "Kettle" in Heintzelman's many books occurs at a minimum in 1972, 1975, 1976, twice in 1979, 1983, 1986 and twice in 2004. Heintzelman should be credited with an early and instrumental interest in the effects of DDT on birds of prey, specifically the effects of the chemical on the size and health of bird populations. He encouraged "civilian" hawkwatching and birdcounts for purposes of monitoring the fallout of DDT starting in 1961. He worked with birdwatching groups to monitor hawks, setting up yearly bird counts in different part of the mid-Atlantic states, and continued these efforts even after the DDT ban went into effect in the United States in 1972. The 1988 membership directory of the Raptor Research Foundation, which lists him as a member, is memorably entitled The Kettle. His research into bird behavior, his efforts to organize hawkwatching that brought ten of thousands to monitor these birds year after year, and his extensive writing career led the term "kettle" catching on as it has.




David Gessner in Soaring With Fidel: An Osprey Odyssey From Cape Cod to Cuba and Beyond (2007) alleges an entirely different kettle of hawks (as an aside, some will smile upon learning that Gessner's book, which contains the words "Cuba" and "Cape Cod" in its very title, is published by Beacon Press). Gessner observes that an area noted for its flocks of hawks rising on thermals from lowlands called der Kessel (the kettle in Pennsylvania Dutch) near Hawk Mountain in Pennsylvania serves as the source of the term for birdwatchers. Gessner's explanation would be on more solid ground if the researchers and scientists at the Hawk Mountain reserve gave at least passing support to this theory on their own website. They do not. Regardless, the existence of the terms boil and cauldron indicate that these names of assembly are based more on the behavior of these birds of prey and not on the name of any particular local landmark.



Dame Berners in The Book of St. Albans (1468) tells us that two individual "hawks of the tower" are called a cast and three such birds should be called a leash. Randle Holme in the Academy of Armory and Blazon (1688) gives us eyrie (now generally spelled aerie) as an additional term of venery for two hawks of the tower and staff for three of the same. Aerie maintains currency as a term for a nest of hawks or other birds of prey, "built high on a cliff or on the top of a mountain." Neither Berners nor Holme specifically discusses what to do for larger groups, though flock always remains a generic possibility. It should be noted that even as early as 1702, A New English Dictionary leaves open the possibility that "cast" might be used for any number of hawks though the dictionary also defines it more narrowly as a "couple" of hawks. Modern sources suggest it is any group of hawks used in falconry. 

Hawks of the tower were for the exclusive use of the upper classes, each species for a different stratum of society: the gyrfalcon for the king, the falcon-gentle for the prince, the saker falcon for knight, and so on. Each of these hawks of the tower, despite that name, is in fact a falcon, a bird in the genus Falco. No one every claimed The Book of St. Albans made any sense, recollecting the word play Dame Berners invites her readers to pursue. By contrast, the lower classes are confined to the goshawk and the sparrow, so-called "hawks of the fist," which are in fact true hawk species in the genus Accipiter and not falcons. These true hawks one properly "lets fly." Thus flight is the proper term of venery here; Dame Berners tells us not to use "cast" either as a name for hawks of the fist or as a verb when these birds are put to flight. 

The irony deepens as these species are in a genus different from those described by Heintzelman's kettles. These latter birds are in a different genus, Buteo, yet are all the same called hawks in North America (Buteo species in the Old World are by contrast called buzzards). Thus in a very real sense, the kettles of hawks in the genus Buteo that Heintzelman has studied and counted are not the St. Albans hawks of the fist which belong to the genus Accipiter. These kettles are likewise not the hawks of the tower (which are really falcons in the genus Falco) about which Juliana Berners attempts to teach the medieval gentleman. Heintzelman's and Berners' terms are in a strict sense not overlapping and apply to different birds in different places.




So many terms to choose from, whether casting or letting fly, by commoners or noblemen or gentlemen, whether gliding on thermals, whether in groups of thousands or groups of two or three, or in nests on a mountain top, whether birds of prey in the Old World and New World, or birds used in falconry that strictly speaking are hawks or not. There are terms of venery as precise or vague or lyrical or poetic as anyone might possibly want to be. Let the game of the hunt begin or let all join the game already in progress. 


As of May 1, 2014 ("name" + "of hawks" per Google):


* cast, 235,000

* flight, 178,000

* kettle, 36,400


* flock, 32,600


* aerie, 9,890


* boil, 1,320


* cauldron, 1,270


* staff, 384


* leash, 224

Subfamily Buteoninae (buteonine hawks)

* hawk or buzzard {en} 

* aligot {ca} 

* gavilán, busardo or ratonero {es}

* buse {fr}

Species in the genus Buteo and others in the New World are called hawks in English, in the Old World they are called buzzards. Buteo species resident in Spain (B. buteo, B. rufinus and B. lagopus) are called busardo; ratonero is also heard particularly for Buteo buteo. Buteo species in the Americas are referred to as gavilán. Oddly, RAE does not record "busardo" nor "ratonero" except in the form "águila ratonera" for B. buteo.

Subfamily Accipitrinae (goshawks, sparrowhawks and hawk relatives)


Genera Accipiter, Urotriorchis, Erythrotriorchis, Megatriorchis


Species named "hawk" in English: 

* astor {ca} 

* azor {es}

* autor {fr}


Species named "goshawk" in English: 

* astor {ca} 

* azor {es}

* autor {fr}

Species named "sparrowhawk" in English: 

* esparver {ca}

* gavilán {es}

* épervier {fr}

Subfamily Melieraxinae (chanting goshawks)

Genus Melierax (Micronisus)


* goshawk {en} 

* astor {ca} 

* azor {es} 

* autor {fr}

"Hawks of the tower" that are in fact falcons and that belong to the genus Falco will be addressed in a future post.