|The Corvids are a large family composed of the familiar crows and jays, plus close relatives like magpies, treepies, nutcrackers and choughs. They show quick intelligence and curiosity, as evident in this Western Scrub-Jay (left) who follows me around during the rare times I pull weeds in my front yard, eager to snatch up any invertebrate I uncover. During the 19th century there arose the belief that these were the “most advanced” birds, based upon the belief that Darwinian evolution brings “progress.” In such a classification the “most intelligent” of birds were listed last reflecting their position “atop the pyramid.” Modern biologists reject the concept of hierarchical “progress” in evolution (the essays of Stephen Jay Gould are particularly good in showing this), so more recent taxonomies place corvids somewhere in the middle of the passerines. They are the largest "songbirds" on earth.|
Most corvids are sedentary without significant migrations, but occasionally a collapse of food supplies will send "invasions" of montane corvids into the lowlands. The Eurasian Nutcracker (right) in the Netherlands was one such vagrant (wandering Clark's Nutcrackers N. columbiana similarly reach my home county in central California during irregular eruptions). Because this Eurasian Nutcracker appeared during a huge birding convention on the Isle of Texel, it was seen by hundreds of twitchers. It was half-surrounded by dozens of photographers when I snapped this shot (perhaps giving it this half-dazed, half-surprised visage....).
more colorful and spectacular corvids are in the tropics. The spectacular
Greg Lasley photo of a Green Jay in south Texas (left) is just one
example of the beauty of tropical jays. In southeast Asia the Green Cissa
chinensis and Short-tailed C. thalassina magpies are striking
examples of unexpected beauty, and Mexico and Central America have numerous
strange and exotic species. Perhaps none is more highly sought that the
Tufted Jay (below) with its outrageous frontal crest. It is endemic
to cloud-forested barrancas in northwestern Mexico, moving in loose bands
that are sometimes hard to find, but curious and approachable when located.
It was only discovered in 1934; many longtime Mexican observers still use
the old name "Dickey Jay" which has a certain panache.
Over a third of the Corvid family (41 species) is comprised of the crows and ravens in the genus Corvus. Nearly all are black (there are a few pied species) and are identified by size, shape, and geography. The most widespread corvid is among these: the Common Raven C. corax. The Large-billed Crow (below left) was called the "Jungle Crow" when I took this photo a quarter-century ago, but it does have a huge raven-like bill. It ranges from eastern Iran to the Orient (southern populations with smaller bills may be split and known again as Jungle Crow; see Madge & Burn 1994). Many of the crows are best identified by voice. This Fish Crow (bottom right) is giving its nasal cry (but you'll have to take my word for it since this page does not come with sound).
|Additional fascinating corvids are the two species of magpie in the
genus Pica. One -- the Black-billed Magpie P. pica -- is found selectively
around the globe in the Holarctic, but the other -- the Yellow-billed
Magpie (above) -- is endemic to California. This striking shot by W.
Ed Harper shows both the bright yellow bill and the extension of yellow
skin into and around the eye. This species lives colonially in California's
dwindling oak savannas but has adapted to residential neighborhoods in
the Central Valley. In Monterey County (where I live) it has not survived
urbanization. While still common in our impressive oak stands in the interior,
the prior isolated populations in Pacific Grove and at Rancho San Carlos
are now extirpated (lots more information in Roberson & Tenney 1983).
Colonial living and helpers at the nest are just some of the interesting
aspects of certain corvids. The local American Crows C. brachyrhynchos
that live in my backyard raise young each year with the help of the prior
year's brood, a character shared with crows on Cape Cod, Massachusetts,
and Northwestern Crows C. caurinus of the Puget Sound area (possibly
just a subspecies of Am. Crow). In contrast, American Crows in the interior
form breeding season pairs and raise young without helpers, but form vast
foraging flocks of all ages during the winter. There is still much to be
learned about these common & ubiquitous birds, not to mention the variety
of little-known ground-jays in the Eurasian interior.
Sibley & Ahlquist (1990) showed that corvids first arose in Australasia
and spread from there around the globe. Early branches of the ancestral
stock evolved into many of the groups of Australasia, including currawongs,
birds-of-paradise, whipbirds, quail-thrushes, whistlers, monarchs and many
others. Both the shrikes and the vireos are offshoots from this root, and
so are African families like bush-shrikes, helmet-shrikes, and vangas.
Sibley & Ahlquist (1990), Sibley & Monroe (1990), and Sibley (1996)
just lumped all these groups into a giant Corvidae family, relegating the
rest of subfamily or tribe status. Such a policy shortens the list of "bird
families of the world" considerably but (fortunately in my view) most ornithologists
confine the Corvidae to just the crows, jays and direct relatives and continue
to consider most of the other groups as separate families. The close relationship
of these groups to the corvids is, however, one of the major findings of
Sibley and colleagues, and has served to reorganize the taxonomic arrangement
of the world's families.
are just too many topics about corvids to be covered in a short web page
like this. There have already been published two major family books, and
the Handbook of the Birds of the World series will certainly add
much rich material when it reaches this point. I am particularly interested
in endemism, and there is a fair bit of it in the Corvidae. The Island
Scrub-Jay (right) is confined to Santa Cruz Island among the Channel
Islands off southern California. Haemig (1989) showed that it differed
from the coastal mainland jays in behavior and several physical traits
(note the big bill compared with the Western Scrub-Jay at top of this page;
also note blue undertail coverts), just as the Florida Scrub-Jay A.
coerulescens was quite different behaviorally in Florida (Pitelka 1951,
Woolfenden & Fitzpatrick 1984). For these reasons, plus biochemical
and fossil evidence, the A.O.U. (1998) split them into three separate
species: Western, Island, and Florida scrub-jays. There is evidence that
interior scrub-jays are also distinctive (Pitelka 1945) and I suspect that
additional research will result in one more split in this group.
There are also isolated endemic crows on several South Pacific islands, some of them now quite endangered like the Guam Crow C. kubaryi, Hawaiian Crow C. hawaiiensis, and Flores Crow C. florensis. Other islands with endemic crows include Sulawesi, New Caledonia, the Solomon Islands, Jamaica, Cuba, and Hispaniola.
|Photos: The Western Scrub-Jay
Aphelocoma californica was in my backyard in Pacific Grove, California,
in May 1989 (actually they're always there; just snapped the shot in May
'89). The vagrant Eurasian Nutcracker Nucifraga
caryocatactes was on Texel, Netherlands, on 15 Oct 1951. The portrait
of Green Jay Cyanocorax yncas is by
Greg W. Lasley who took it 17 Feb 1999 in Starr Co., Texas. The
Tufted Jay Cyanocorax dickeyi was along the Durango Hwy,
Sinaloa, Mexico, on 22 Feb 1987. The Large-billed
Crow Corvus macrorhynchos was at fairly high elevation
at Pahalgam, Kashmir, India, in Aug 1978. The Fish
Crow Corvus ossifragus was calling at Manteo, North Carolina,
or 3 Aug 1997 (Joe Morlan & Dan Singer can confirm the i.d.) Ed Harper
took the fine Yellow-billed Magpie Pica
nuttalli photo near his Sacramento, California, home in 1997.
The Island Scrub-Jay Aphelocoma insularis
was, of course, on Santa Cruz I., California; photo is dated 17 Aug 1992.
Photos © Don Roberson except those attributed to Greg W. Lasley and
W. Ed Harper who hold those copyrights, used with permission here; all
(out of 5 possible)
This was considered a monumental effort at the time it came out, and was one of the first bird family books I acquired. Unlike the recent plethora of cookie-cutter family books, this one was just not a set of species accounts put together within one cover. The first third of the book is detailed text about the Family: a summary of what was then known about corvid biology, ecology, and behavior. In this sense it is like the recent family summaries in the Handbook of the Birds of the World. The species accounts were as updated as was then possible, but for obscure species like Flores Crow or Banggai Crow the subheads "Feeding," "Nesting, "Voice," and "Social Behavior" all read "No information." In contrast, a common European species like Rook went on for 8 pages. Every species had a black-and-white sketch (some showed behavior also) but the few color plates showed some just an example or two of each genera, and all were done in an unattractive "cut-out" side-view field-guide style. This book does not measure up to today's information, but was not bad for its time and the information seemed accurate. It was conservative in taxonomy and covered 116 species (but did split today's Gray Jay into two species). It is now a "classic" and is cited again and again in the literature, but is outdated except for its good summary of biology for the more common species.Family Book: HHH (out of 5 possible)
Madge, S., and H. Burn. 1994. Crows and Jays: A Guide to the Crows, Jays and Magpies of the World. Houghton Mifflin, Boston, MA.
In stark contrast to Goodwin (1976), this modern book has almost no introductory information about the Family Corvidae. Instead it has the now familiar set of color plates for every species opposite short details and a range map, and then the bulk of the book is species accounts. These are telegraphic in nature and pack a lot of information, but Rook takes up only two pages while both Flores and Banggai crows are a full half-page each. We learn that the Banggai Crow is known from only two old specimens and that it may be extinct; recent crows sightings from this little island off Sulawesi may be expanding Slender-billed Crows. For the endangered Flores Crow the voice is now known, but habits and breeding details still are unknown. Thus this book does nicely update Goodwin's information. The artwork shows more natural birds than those in Goodwin, and is quite attractive. The authors are liberal in taxonomy and list 120 species, including splits in Short-tailed Magpie, Eurasian Nutcracker, and Large-billed Crow (among others), decisions that still are not widely accepted [yet they did not anticipate the three-way split of Scrub Jay]. They include a nice i.d. chart of Australian crows/ravens, but then favor the split of "C. boreus" proposed by Rowley (1967), the "Relict Raven" of New South Wales, a position not generally followed by Australian ornithologists. They further confuse the matter by using the English name "New England Raven." Only an Aussie (Rowley) and two Brits (Madge & Burn) could think this was an appropriate English name from a worldwide perspective; never mind the millions who think they live in "New England" in the northeastern United States!Literature cited:
American Ornithologists' Union. 1998. Check-list of North American Birds. 7th ed. A.O.U., Washington, D. C.
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