These experiences do not come easily. It took me seven trips over 24
years into Harpy Eagle habitat to observe one. Once, in eastern Ecuador,
Rita & I were on a trail deep in the forest with local guide, Fausto.
As we struggled unsuccessful to see a monklet heard by the guide, Fausto
wandered down the trail and was shocked by a Harpy Eagle gliding into the
canopy, snatching a monkey, and flying off. Rita & I missed it just
by moments and a few yards....
While the huge tropical eagles impress with their size & strength, they are not the spectacular flying machines epitomized by the migratory hawks. The Arctic breeding Rough-legged Hawk (right) is one of those long-distance migrants. Regular in winter in the interior of North America, during "invasion years" immatures (like this one) may turn up hundreds of miles farther south. Other American species, including Broad-winged Hawk Buteo platypterus in the east and Swainson's Hawk B. swainsoni in Mexico, migrate in incredible numbers, circling in huge "kettles" on the rising thermals [some great eastern U.S. sites to observe hawk migration were outlined in Heintzelman (1976); the impressive California site at Pt. Diablo, Marin Co., is fully discussed in Binford (1979)]. I am aware that raptor migration can be just as impressive in the Old World, at places like Falsterbo, Sweden; the Bosporus, Turkey; and Eilat, Israel. Many of these are in the genus Buteo, and they are often the "standard" hawk in temperate climes around the globe. In California, for example, our usual hawk -- the default i.d. for any large soaring raptor -- is the Red-tailed Hawk (below left). Like many hawks, it comes in a bewildering variety of plumages and color morphs, the whole spectrum of which cannot be shown in any literature. One learns to use shape, size & behavior.
This particular Red-tail is an adult that had caught a large Gopher Snake in the middle of a country road, and was struggling with it at road's edge when we came upon it (you can see the snake's tail just sticking out on the left side of the back). While reptiles comprise only a small portion of the Red-tail's prey, numerous hawks specialize on snakes, including three species of snake-eagle (Circaetus) in Africa and six species of serpent-eagles (Spilornis) in Asia, plus another serpent-eagle (Dryotriorchis spectabilis) in the Congo basin, Africa.
Perhaps the most graceful of the Accipitridae are the kites. The Old
World species (especially Black Kite Milvus migrans) can be too
ubiquitously common, but a lot of New World species are either very lovely
& graceful, or specialized and cool. An example of a specialized bird
is the Snail Kite (below) whose dietary preferences run primarily
to the apple snail Pomacea, although it will take a variety of crustaceans.
There are a huge number of bird-eating hawks in the world, most of the genus Accipiter (49 species comprising 20% of all the family). Many species are rare & local; many are difficult to identify. For North America, a good starting point for Accipiter i.d. is Dunne, Sibley & Sutton (1988). I photographed an Accipiter in Madagascar in 1995, but it wasn't until the appearance of Morris & Hawkins (1998) that I could confidently identify it as Frances' Goshawk A. francesii. There is much to be learned with this group. Many Accipiters fly through the forest in search of small avian prey; some even frequent bird-feeders. In North America there are two widespread species, difficult to separate without practice. The one shown below (left) is the Cooper's Hawk (an adult male in flight). Most harriers (genus Circus; 13 species) glide over marshes or open country on tilt-up wings searching for small mammals and birds. A pied example (below right) is the Eastern Marsh-Harrier (or Spotted Marsh-Harrier) of eastern Asia, wintering to New Guinea.
There are also a number of shy, hard-to-see, forest hawks, like those in the genus Leucopternis of the New World tropics, that are very much a treat to find. Another group of tropical hawks -- genus Buteogallus -- specialize in feeding along streams or estuary edges, eating amphibians (especially frogs), crabs and freshwater crayfish, along with small mammals & reptiles. Few of them soar much, but the two below do: the White Hawk (left) and the Common Black-Hawk (right). I've always thought it would be [keen/groovy/cool/hot/fat -- you pick the slang] to show a White Hawk next to a Black Hawk, so here they are. Note how both have broad wings and very short, broad tails.
Yet another entire set of species make up the Old World vultures (these prove to be unrelated to New World vultures which are actually modified storks; see my New World Vulture page). Huge mobs of these beasts at a carcass are a unique part of a trip to the open plains of Africa or India [below, top photo; mostly White-rumped (Indian White-backed) Vultures with a few Long-billed Vultures Gyps indicus and even a Steppe Eagle Aquila nipalensis]. At a major carrion feast, larger and more specialized vultures may arrive, equipped to eat bone and sinew. The top of the African vulture chain is the Lappet-faced Vulture (below left in a great photo by Dale & Marian Zimmerman; smaller vulture sneaking in from the right is a Rueppell's Griffon G. rueppellii).
This brief survey has focused primarily on the major subgroups of hawks & eagles, but over half of the present genera (36 out of 64) are monotypic (Thiollay 1994). These include many little known and elusive raptors of tropical forests. On the other hand, some of the Accipitridae are so well known that they become icons for their lands. Excellent examples are two fish-eating eagles: the Bald Eagle (below left) of North America and the African Fish-Eagle (below right) of sub-Saharan Africa. Each has been photographed innumerable times; I pick these particular shots because (for the Bald Eagle) it is of the only modern record of an undoubtedly wild bird at Pt. Pinos, just blocks from where I live, and (for the Fish-Eagle) because I just love this Greg Lasley flight photo.
For the Bald Eagle, I say the only modern "undoubtedly wild" bird because the Ventana Wilderness Society began an effort in 1986 to re-establish a wild population of Bald Eagles on the central coast of California. They did so by bringing fledgling from British Columbia, "hacking" them to independence on the Big Sur coast, and radio-tracking their movements (for more details, see their web site here). By 1993, a pair of released eagles were nesting nearby; now there are about a half-dozen nesting pairs. This is a wonderful success, but we can no longer tell whether an eagle seen locally is a migrant from the north or an offspring of the re-introduction project. But the Pt. Pinos photo, taken in 1989, was before any of the released birds had gained full adulthood, so we know this adult was a wild migrant. It spent several days snatching fish from the surf line at Pt. Pinos, and was even videotaped doing so by a local TV news crew.
Hawks and eagles fascinate many people -- not just birdwatchers -- and the literature is enormous. One can hardly do justice to a family like this on a short website page. A very fine (and longer) introduction, with a superb collection of photos, is in Thiollay (1994).
Photos: The adult Harpy Eagle Harpia harpyja was photographed on 4 Aug 1999 in the Serra das Araras, sw. Brazil. The Rough-legged Hawk Buteo lagopus was soaring over Honey Lake, Lassen Co., California, in Feb 1981. The adult Red-tailed Hawk B. jamaicensis caught its gopher snake near California Hot Springs, Tulare Co., Calif., on 20 June 1997. The adult Snail Kite Rostrhamus sociabilis was in the Pantanal of Brazil in Aug 1999. The adult Cooper's Hawk Accipiter cooperii was in flight over Moonglow Dairy, Monterey Co., Calif., on 23 Dec 1990. The male Eastern Marsh-HarrierCircus spilonotus (called "Spotted Harrier" in some literature) was a migrant to the Baliem Valley, Irian Jaya, New Guinea, on 2 Aug 1994. The White Hawk Leucopternis albicollis was over the Serra das Araras, Brazil, in Aug 1999, and the Common Black-HawkButeogallus anthracinus was in Aravaipa Canyon, Arizona, USA, on 9 July 1982. The feasting vultures, mostly White-rumped (or Indian White-backed) Vultures Gyps bengalensis, were near New Delhi, India, in Aug 1978. Dale & Marian Zimmerman took the great close-up of Lappet-faced VultureTorgos tracheliotus in Kenya in Aug 1979. The Palm-nut VultureGypohierax angolensis was at La Lopé Reserve, Gabon, in July 1996. The adult Bald EagleHaliaeetus leucocephalus was at Pt. Pinos, Monterey Co., Calif., on 11 Feb 1989. Greg W. Lasley photographed the African Fish-EagleH. vocifer along the Okanvango River, Botswana, on 22 Oct 1998. All photos © D. Roberson, except those attributed to Dale & Marian Zimmerman and Greg W. Lasley, respectively, whose photos are used with permission. All rights reserved..
Family book: Rating HHHH
Brown, Leslie, and Dean Amadon. 1968. Eagles, Hawks, and Falcons of the World. 2 vols. McGraw-Hill, New York.
When this two-volume boxed set came out in the late 1960s, it was the state of the art on knowledge of the world's raptors. It covered hawks & eagles, plus falcons and the monotypic families of Osprey and Secretarybird. The authors were renowned experts on the subject; the text was reasonably thorough and the range maps up-to-date (for the time), and every species was pictured on full-page plates showing one to a half-dozen birds. Sometimes these were six species together; on other plates it showed age/sex variation, or color morphs, or subspecies. Eight artists were included, among them legendary names like Roger Tory Peterson (Old World vultures), Don Eckelberry (large falcons, including full page paintings of birds like an Indian Peregrine perched against the backdrop of Rangaswami's Pillow -- a fantastic rock formation -- in south India), A. E. Gilbert (great tropical raptors) and D.M. Henry (his plate of variation in Gyrfalcon is superb), and Guy Coheleach (a variety of eagles and Buteos). J. C. Harrison seems to have done most of the lesser-known species... the "grunt work" as it were (and a good number are printed in black-and-white. In a book like this, the differences in artistic style is almost welcomed; these are not "field guide" art to be compared one to another, but a collection of great artwork combined with an authoritative text.There are regional works to which one turns much more readily for identification material. In North America, the best work is Wheeler & Clark (1995) whose set of superb color photos show much more of the range of variation present in Nearctic raptors than anything else, and far surpasses their earlier effort (Clark & Wheeler 1987). Beginners, however, are well advised to obtain and read Dunne, Sibley & Sutton (1988) who capture in worlds and line drawings the essential shape characteristics of common (but confusing) species. In Europe and the Middle East, I have found Porter et al. (1981) very useful, but the new Forsman (1999), with many great color photos, appears to be a major advance.
All that having been said, the classic work is now showing its age. Much has been learned in the last quarter-century about ranges; about status; about biology and taxonomy and identification. Yet in many respects Brown & Amadon's achievement stands the test of time. It is still a primary reference work on the world's raptors, and their taxonomic comments (especially at the species level) are still entitled to much deference. One clue to its value is that no more modern work even comes close to competing with it (I am aware, however, of some projects in the works).
Binford, L. C. 1979. Fall migration of diurnal raptors at Pt. Diablo, California. W. Birds 10: 1-16.TOP
Clark, W. S., and B. K. Wheeler. 1987. A Field Guide to Hawks of North America. Houghton Mifflin, Boston.
Dunne, P., D. Sibley, and C. Sutton. 1988. Hawks in Flight. Houghton Mifflin, Boston.
Forsman, D. 1999. The Raptors of Europe and the Middle East: a Handbook of Field Identification. T. & A.D. Poyser, London.
Heintzelman, Donald S. 1976. A Guide to Eastern Hawk Watching. Pennsylvania State Univ., University Park, PA.
Morris, P., and F. Hawkins. 1998. Some comments on the identification of six Madagascar raptors. Bull. African Bird Club 5: 114-119.
Porter, R. F., I. Willis, S. Christensen, and B. P. Nielsen. Flight Identification of European Raptors. 3d ed. 1981. P. & A.D. Poyser, Calton, England.
Thiollay, J. M. 1994. Family Accipitridae (Hawks and Eagles) in del Hoyo, J., Elliott, A., & Sargatal, J., eds. Handbook of the Birds of the World. Vol. 2. Lynx Edicions, Barcelona.
Wheeler, B. K., and W. S. Clark. 1995. A Photographic Guide to North American Raptors. Academic Press, London.
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