Crane hawk (Geranospiza caerulescens) is found widely in the New World tropics. This is a 18 to 21 inch hawk that is all gray in color. The tail, however, is black with white bands. When flying the outer wing feathers are black with a white stripe.

Monroe in 1993 listed three species:
G. caerulescens ssp nigra - C. America & NW South America
G. caerulescens ssp caerulescens - Amazon Valley
G. caerulescens ssp gracilis - SC and E South America

Howard and Moore in 2003 listed 6 subspecies.
ssp livens - NW Mexico
ssp nigra - Mexico to Panama
ssp balzarensis - east Panama to NW Peru
ssp caerulescens - eastern Ecuador, Colombia, Guyanas and N. Brazil
ssp gracilis - NE Brazil
ssp flexipes - southern Brazil, Bolivia, and northern Argentina

Clements in 2007 shows 6 subspecies as follows:
G. caerulescens ssp livens - NW Mexico
G. caerulescens ssp nigra - Mexico to Panama
G. caerulescens balzarensis - S. Panama to western Peru
G. caerulescens caerulescens - Guyanas and Amazon Valley
G. caerulescens gracilis - NE Brazil (Local)
G. caerulescens flexipes - south S. America (Paraguay, Bolivia, etc)

Robin Restall in his excellent book "Birds of Northern South America" shows 5 different drawings covering two subspecies.
The adult subspecies balzarensis is almost totally black with two pale bands on the dorsal tail with a pale tail tip. He shows an immature with a pale breast marked with horizontal thin brown bands.
The shows an adult subspecies caerulescens with a totally grey coloration with the same two bands. The immature caerulsescens has a grey breast marked with some thin white lines.

He also shows a juvenile in the center that can apply to either of the above subspecies. This juvenile has a pale head and a pale throat. The breast is pale, but marked with thin brown bars. The juvenile can show an extra white bar.

All forms displayed show orange lower legs and feet.

He also shows three ventral views in flight, and notes the grey ventral side with a white bar near the wing tips is diagnostic.

Mr. Restall has set a new standard of excellence, and we recommend the volumes in this series!

The crane hawk genus (Geranospiza) contains a single species. This genus is found from Central America south through most of tropical South America to northern Argentina. This 18 inch (45 cm) male and 21 inch (53 cm) female crane hawk is generally gray with a black tail crossed with typically 2 white bands.

Rodner, Lentino, and Restall suggest in the year 2000 that caerulescens and balzarensis might be two different species. (Editors Comment: Since balzarensis is found along the western drier areas of South America, this lifeform might indeed have a different genetic composition.)

There are two South American genera in the hawk and eagle order with similar spellings: Geranospiza and Geranoaetus.

Hawks and Eagles (Family Accipitridae) are a group of 205 species found in most areas of the world. Actually, the common terms of eagle, hawk, kite, buzzard, and vulture are rather loosely used, and consequently, are not much help in understanding this family. Here, this family has been separated into seven groups: typical hawks, Old World vultures, eagles and related hawks, fish eagles, kites, harriers and marsh hawks, and a misc. group. A more precise division might be:
Aegypinae - Old World Vultures -
Elaninae - White Tailed Kites - 7 species
Perninae - Swallowtailed and Hook Billed Kites
Milvinae - True kites -
Accipitrinae - Hunting hawks - 40 species
Buteoninae - Large hawks and eagles - 90 species
Circinae - Harriers and marsh hawks - 17 species
Circaetinae - Serpent eagles

There is no universal agreement on the division of this group, and some authors lump them altogether. We hope our arbitrary separation helps in the study of this group.

Birds of Prey (Order Falconiformes) group contains the eagles, hawks, falcons, Old World vultures, and related birds. The majority of the species in this group feed on small animals, fish, and other birds. A few species eat dead animals. Most of them are excellent fliers and have very strong legs and claws for grasping their prey. There are about 239 species in the hawk and eagle group and about 61 species in the falcon group. When you include the unique osprey and the unique secretary bird, you total about 302 species more or less depending upon a few controversial subspecies.

(The 7 species of New World vultures have recently been placed near the pelicans and storks and were not counted in our 302 number. However, for historical reasons we have left those vultures below here, as our purpose is defining species, and helping users navigate the large number of species.)

Aves contains about 8,650 different species of living birds known to science. Each year about one new species is discovered in some remote rain forest or remote island. In addition, scientists have been raising many subspecies to full species status which may raise the species count to 10,000. Birdlife recognizes 10,027 species as of 2011.

However, each year about one species goes extinct. The rate of extinction is increasing, and the rate of new discovery is decreasing, so that the number of bird species will soon begin to decline rapidly. Although different taxonomists would organize the birds differently, there are approximately twenty-seven orders of birds. These orders are broken down into about one hundred and fifty-five different families.

Recent research of the genetic structure of some of the shore birds and owls would indicate that the present organization of orders and families should have some modification.

The birds are a worldwide group of animals that are characterized by having the front limbs modified into wings that are used for flying. Perhaps the most unique feature of the birds is the feathers. These feathers are made up of a central support called a quill and a series of small filaments that are hooked together as barbs.

For many years it was believed that Archaeopteryx discovered in Bavaria was the oldest bird from about 150 million years ago. However, in l986, Sankar Chattterjee, a Texas paleontologist, reportedly discovered a bird in the genus Protoavis that lived about 225 million years ago.

When this project was begun in 1978, we used Austin & Singer for bird taxonomy. Since then, we have adopted many changes, but have kept some older concepts that are still found widely in the literature. Recently, we have used Clements and Howard & Moore. Very recently, we have used Monroe and Sibley for the higher taxonomy of the perching birds.

Backboned Animals (Phylum Chordata) are the most advanced group of animals on earth. These animals are characterized by having a spinal cord or backbone. Most members have a clearly defined brain that controls the organism through a spinal cord. Fish, amphibians, reptiles, birds, and mammals are in this phylum.

Currently, some taxonomists believe that the fish should be divided into two groups (sharks and regular fishes) and that there are some other primitive groups in the phylum such as hagfish or lampreys.

Animal Kingdom contains numerous organisms that feed on other animals or plants. Included in the animal kingdom are the lower marine invertebrates such as sponges and corals, the jointed legged animals such as insects and spiders, and the backboned animals such as fish, amphibians, reptiles, birds, and mammals.

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