Cranes

(Gruidae)

Class Aves

Order Gruiformes

Suborder Grues

Family Gruidae

Thumbnail description
Large birds with long neck and legs, usually gray or white plumage

Size
35–70 in (90–176 cm); 4.4–26.5 lb (2–12 kg)

Number of genera, species
4 genera; 15 species

Habitat
Typically inhabit shallow wetlands from tropical areas to the Arctic

Conservation status
Vulnerable: 5; Endangered: 6

Distribution
Present in all regions except Antarctica and South America

Evolution and systematics

Cranes are an ancient family that dates back some 40–60 million years to the end of the Age of the Dinosaurs in the remote Eocene. More than a dozen extinct species are represented in fossil records.

The Gruidae's closest relative is the New World limpkin of the family Aramidae. Somewhat smaller than cranes, limpkins have an upright stance and loud calls reminiscent of cranes. The next closest relative to the cranes and limpkins are the New World trumpeters of the family Psophidae. Native to the tropical forests of South and Central America, the jumpy behavior and the plumage of trumpeters somewhat resembles that of the most primitive of cranes, the crowned cranes. These close links of cranes to New World families suggests that the pro-crane originated in the New World and subsequently expanded into Asia where their closest relatives are bustards of the family Otidae—a family that is restricted to the Old World. From Asia, ancient cranes probably extended their ranges into Africa and Australia.

Crowned cranes are placed in the subfamily Balearicinae, and differ from cranes of the subfamily Gruinae in many ways. Crowned cranes have loose plumage and the inability to tolerate extreme cold. Gruinae cranes have compact plumage and are cold-hardy. Balearicinae cranes have elongated hind toes (hallux) and perch in trees. Gruinae cranes have vestigial short hind toes and seldom perch in trees. As the name suggests, crowned cranes have elaborate bristle-like feathers on the hind part of their heads that look like golden crowns. While Gruinae cranes lack this plumage, portions of the heads of most species are covered by predominantly bare red skin that is used in display. The trachea of crowned cranes proceeds directly from the neck to the lungs in contrast to the trachea of the Gruinae that coils to varying degrees into the sternum. The prevalence of extinct species of crowned cranes in fossil records in North America, suggests that the Balearicinae or its ancestor gave rise to the Gruinae. Today there are two living species of Baleariciae, both of the genus Balearica and both restricted to wetlands amidst the grasslands and savannas of sub-Saharan Africa.

The Gruinae includes thirteen species of the typical cranes. Although comparative studies of their DNA by American scientist Dr. Carey Krajewski suggest they all can be considered members of a single genus Grus, the species are divided into three genera—Grus, Anthropoides, and Bugeranus—based on anatomical and behavioral evidence.

The Grus includes 10 species divided into four subgroups, the Siberian; the sandhill; the Group of Five (Eurasian, whooping, hooded, black-necked and red-crowned); and the Group of Three (brolga, sarus, and white-naped). Anthropoides includes demoiselle and blue cranes, while Bugeranus has the wattled crane.

The Siberian is the enigma of the Gruinae. Although resembling the whooping crane with glistening white plumage and black primary flight feathers, the red facial comb is restricted to the area in front of the eyes, giving it a nun-like look and a pattern somewhat similar to that of the comb of the wattled crane. The reduced coiling of its trachea and its feeding behavior is also similar to the wattleds. But these similarities with Bugeranus are perhaps the consequence of convergent evolution. DNA of the Siberian suggest the species is definitely a Grus but with a more distant relationship to the remaining nine species within that genus.

The sandhill has some behavioral links to Siberian cranes but more DNA, anatomical, and behavioral links to the Group of Three. Within the Group of Three, DNA suggests the white-naped of Asia and the brolga of Australia are more

closely related to each other than to the sarus of south Asia. Anatomical evidence suggests the brolga and the sarus are more closely aliened. DNA suggests the red-crowned crane is most distant within the Group of Five, and that the Eurasian, whooping, hooded, and black-necked cranes are closely related to each other. Perhaps the whooping crane arose from a stock of Eurasian cranes that immigrated into North America from Asia.

DNA suggests that the wattled crane is closely related to the demoiselle and blue cranes. Wattled cranes are adapted to African wetlands while the Anthropoides species live predominantly in grasslands in southern Africa (blue) and in Asia and north Africa (demoiselle). Perhaps the demoiselle cranelike ancestor from Asia radiated into African wetlands and grasslands to become the wattled and the blue cranes.

Physical characteristics

Cranes are large, long-legged, long-necked birds that typically inhabit shallow wetlands. They have loud calls that can carry for several miles.

Distribution

Cranes occur on all continents except Antarctica and South America.

Habitat

Most cranes nest in wetlands, where they also feed. Many species use freshwater wetlands in their summer breeding areas, but may use saltwater coastal marshes in their wintering ranges. Two species of cranes predominantly inhabit grasslands.

Behavior

Cranes of northern latitudes migrate thousands of miles (kilometers) south to wintering areas. When prevailing winds are correct, cranes climb mid-morning thermals to glide. While gliding they are not in "V" formation. However, when flap-flying without the aid of thermals, they do fly in "V" formation. For each crane population there are usually one or two traditional staging areas where the cranes remain for several weeks during migration. Otherwise, when migrating, cranes fly until late in the afternoon or evening and then roost opportunistically at available wetlands. Juvenile cranes remain close to their parents during migration and throughout most of the winter. Sometimes they accompany their parents back to natal areas in spring, and sometimes they leave their parents before or during the spring migration.

Cranes that live in warm climates typically breed during the wet season or seasons and gather in flocks during the dry season. Flocking is usually greatest just before the onset of the next breeding season and is presumed to facilitate integration of juveniles in sub-adult flocks and genetic mixing as new pairs form in the flocks.

Crane calls

Cranes are well known for their trumpet-like calls. Aldo Leopold said it best, "When we hear his voice we hear no mere bird. He is the trumpet in the orchestra of evolution. The sadness discernable in some wetlands stems from their once having harbored cranes. Now they stand humbled adrift in history."

Within the Gruidae, there is an evolutionary progression from the simpler displays in the ancient crowned cranes through a progression of "middle species" to the most elaborate displays in Siberian and red-crowned cranes. The most fundamental call in all cranes is the low, purr-like contact call. It is given by cranes that are familiar with one another in a flock, between members of a pair, and from a parent crane to its egg and chicks. Apparently it signals compatibility and well being. In sharp contrast to the soft contact call is a nasal hiss or deep growl, both of which signal acute aggression.

The black crowned cranes have one single-syllable loud honk-like call that appears to suffice in many circumstances. Likewise, the gray crowned crane has a two-syllable call that is commonly performed. Crowned cranes are unique in possessing an inflatable sac beneath the head that is inflated when performing a series of boom-like calls at the onset of the breeding season. This gular sac is larger in the gray crowned crane and at least in captive cranes "booming" is more frequently performed in gray crowned than in black crowned cranes.

Within the Gruinae, there is a whole series of distinct and somewhat complicated calls that are difficult to describe. The alarm call immediately causes other cranes to become alert and perhaps to fly. The flight intention call signals just that. The loud flight call perhaps helps maintain flock cohesion. The low groan call signals acute pain. The piercing guard call warns of both danger and of the individual's aggression. The trumpeting and prolonged unison call—a duet of mated pairs—is a threat to other cranes. The duration and the intensity of the calls can vary depending on the condition of the crane emitting the call.

Crowned cranes have honk-like calls. Anthropoides have low broken calls that are remarkably similar to the calls of sandhills. Wattled cranes are generally silent, and when they do call, the voice is high-pitched and somewhat squeaky. Siberian cranes have soft flute-like calls that are simpler in structure than the call of other Grus species. Sarus have the loudest and shrillest calls of cranes, and brolgas have the lowest calls. As its name suggests, the whooping crane has a penetrating call that carries for great distances over the wetlands.

The voice of the Gruinae cranes is modified by coiling of the trachea in the sternum. The trachea of Siberian cranes and wattled cranes makes a slight dip into the sternum: their calls are high frequency and of less intensity than in other cranes. In the remaining Gruinae species there are varying degrees of coiling, the most advanced being in the Group of Five (Eurasian, whooping, hooded, black-necked, and redcrowned) where the length of the trachea is doubled by two coils that penetrate the entire length of the sternum. The tracheal rings fuse with the sternal bone to create a plate between the tracheal passage and air sacs on the outer side of the sternum. The vibrations of these bones are believed responsible for the amplification of the calls of the crane. If an operation is performed to bypass the sternum and lead the trachea directly from the lower neck to the bronchi, the crane's voice becomes a whisper.

Individual cranes can be identified by "voice prints." Remarkable research by German scientist Dr. Bernard Wessling reveals that recordings of guard calls and unison calls of Eurasian, red-crowned, and whooping cranes can be used to identify individuals. Catching cranes for individual marking with color bands is difficult for humans and dangerous for cranes. Voice printing provides many new opportunities for research to better understand the biology and thus the needs of the endangered cranes.

Threats and dances

The head is the most important unit for communication in cranes. Not only is it the outlet of calls, but also it has many visual features used in communication.

Crowned cranes have bare skin on the sides of the head, tiny black fur-like feathers on the forehead, and elaborate crests. They are the only cranes that commonly all preen each other's heads in what appears to be both a maintenance activity and a sexual display.

The Anthropoides have completely feathered heads with elongated plumes on the side of the head that can be raised during display to increase the apparent size of the head. During display a blue crane elevates these feathers creating a cobra-like look. A triangle of white plumes form just behind the bright red eye of the demoiselle, and can be elevated and fanned open. Wattled cranes elongate their drooping flaccid wattles. Blue, demoiselle, and wattled cranes all use their bills while displaying.

The Grus species have areas of conspicuous red skin on their heads. In Siberian cranes the red skin extends from the eye down along a central groove in the upper mandible. The portion on the top of the head is pulled back slightly when the crane displays. In sandhills, as in Siberians, the red extends from the facial area over the top of the head. When not displaying, the red area can be pulled forward so the backside of the head is then covered by gray feathers.

In the Group of Three (brolga, sarus, and white-naped), the sides of the head are covered by bare red skin, and in the brolga and sarus the red continues down the upper portion of the neck. The feathers covering the ear holes are conspicuous as gray circles surrounded by red skin. The Group of Five somewhat like the sandhill, have red on the top of the head that can be pulled down over the back of the head in display. The ability to voluntarily expand and contract the size of the area of bare red skin gives the crane an ability to communicate in degrees.

Cranes that fear other cranes often adopt a submissive posture and reduce the display component of their heads. With neck retracted and feathers slightly ruffled, a crane communicates submission. In sharp contrast, a crane that communicates aggression and/or sex holds its neck and head high, elevates the inner half of the toes above the substrate, sleeks is plumage, protrudes its thighs, and displays its tertials. From this classic threatening posture a crane can perform a series of complex threat postures and rapid sequence of postures.

The following outlines common threat displays of several species:

• Crowned—upright, then ruffles wings with head lowered and then head up.
• Blue—neck up, head puffed, head lowered to near ground and at same time ruffles elongated tertials, raises head and puffs sides of head while simultaneously moving tail back and forth rapidly.
• Wattled—open wings, held open for a second, closed rapidly, false preens shoulder feathers, head up, ruffles wings, tail back and forth rapidly.
• Siberian—flaps with strength with head lowered to ground level, ruffles, snaps head and neck up and false preens shoulder with wing dropped vertically.
• White-naped—exaggerated flap of wings and head and neck lowered between legs as wings open, as wings close head and neck brought up and then back over the back in spring-like manner, head up, wings ruffled and at same time head and neck lowered to false preen the thigh.
• Red-crowned—exaggerated flap of wings, with wrists closed, humeri raised high over back, red of head turned sideways against black elevated tertials.

One of the highest intensity threat displays is the crouch threat, whereby a crane sits on the ground in front of an adversary in a posture that resembles incubation posture. The beak is often pressed into the substrate and the wings are

sometimes partially opened. From this prostrate-like posture, a crane can leap up and attack.

If threat displays do not resolve a conflict, cranes engage in a ritualized fight that usually does not injure the participants. The combatants approach each other in threat posture, face each other, and then leap up with legs folded. The feet strike at the opponent's breast and both birds are vigorously pushed in opposite directions. During this split second of contact, the dominance relationship is established. When the cranes land, they are separated by several meters. The subordinate bird usually slowly walks away in reduced threat posture. Through this ritualized combat serious injuries are avoided and social relationships are determined. This type of conflict frequently occurs when cranes gather in flocks.

Territorial cranes are acutely aggressive to other cranes. If an intruder approaches a piece of defended real estate, in the majority of the species, the resident pair releases a unison call for an extended period. This display usually results in the departure of the intruders. However, if the intruder continues to penetrate the territory, the resident birds often attack with vigor and the intruder departs. Seldom will an intruder attempt to stand up to the attacks of a resident pair. There is a significant psychological advantage to holding a territory.

Feeding ecology and diet

Cranes can be divided into three groups based on beak proportions and associated foraging behavior: the short-beaked, the medium-beaked, and the long-beaked. The shorter the beak, the more dependent a species is on uplands; conversely, a longer beak allows for a wetland-dependent species.

The short-beaked cranes include the Balearica, Anthropoides, and the lesser sandhill. Balearica and Anthropides forage predominantly in grasslands and agricultural fields, while the lesser sandhills feed in more upland and drier portions of the tundra. During migration and on their wintering grounds these sandhills also forage in grasslands and agricultural fields. The short beaks of these cranes are adapted for grasping insects, seeds and for grazing in a manner somewhat similar to the grazing of geese.

The medium-beaked cranes include five other subspecies of sandhills, Eurasian, hooded, and black-necked cranes. These cranes often forage in uplands like the short-beaked cranes. Harvested grain fields rife with gleanings are particularly important to these cranes during the nonbreeding season. During the breeding season, as well as feeding in nearby and drier uplands, these cranes also forage on a wide variety of plant and animal life in the wetlands.

The long-beaked cranes can be divided into two groups: the diggers (Siberian, wattled, and the Group of Three) and the catchers (red-crowned and whooping). In a quest for the flesh tubers of sedges, the diggers excavate holes up to approximately 1.6 ft (0.5 m) deep in wet mud. Although the diggers can be catchers and the catchers can be diggers, the diggers typically dig in wet soils for the nutrient rich portions of aquatic plants, while the catchers gently probe the bottoms for live animals.

Cranes that have adapted to a human-altered habitat by foraging in pastures and harvested fields are more successful than species restricted to wetlands. Gleaning in agricultural fields in southern areas of both North America and Eurasia, have undoubtedly contributed to the increase in numbers of demoiselle, sandhills, and Eurasians into the hundreds of thousands. Conversely, the more dependent on aquatic habitat, the more endangered the species. The Siberian crane is the most wetland dependent of the diggers and it is considered to be the most endangered species of cranes, although not the rarest—a distinction held by the more wetland-dependent of the catchers, the whooping crane.

Young cranes require a high-protein diet of live animal food independent of the beak type and foraging habitat of adults. Foraging patterns with the young cranes closely resemble those of adult cranes with the exception that the families usually spend more time in wetlands. The Balearicinae forage for live animal food in both wetlands and neighboring uplands. The Anthropoides pairs walk quickly with their juveniles through the uplands on a seemingly urgent quest of insects and other small animals. The medium-beaked cranes forage in both aquatic and upland habitats, while the long-beaked cranes are more restricted to the wetlands.

Vegetation stomping is performed to flush insects that are then grabbed. This behavior is most prevalent in crowned cranes and is included in a ritualized manner in their courtship dance. Cranes of all species will trample down dense emergent aquatic vegetation to create a flat open habitat for their chicks. Presumably the vegetation forms a mat on which the chicks can walk and from which they can more readily catch insects.

Reproductive biology

Cranes are monogamous birds and usually pair in their second or third year and start to breed in their fourth or fifth year. Pairs defend breeding territories that usually include many acres (hectares) of open wetlands or grasslands. A low platform nest is constructed of materials available in the wetland. A clutch of two eggs is typical. The incubation period of about one month is followed by a prefledging period of about 2–3 months.

Young cranes are precocial and remain with their parents for about 9 months. If there is more than one juvenile in a family, there is usually a dominance hierarchy among the chicks. Parents partially feed the juveniles and dominant birds receive proportionately more food from the parents. In times of food scarcity, subordinate juveniles are the first to perish. Most successful pairs usually rear only a single offspring per breeding attempt. After juveniles fledge, cranes usually abandon their territories and gather in flocks and feed in areas of food abundance. At night they roost in flocks in shallow water to better escape terrestrial predators.

Cranes that are completely white (Siberian, whooping, redcrowned) or that have white necks (white-naped, wattled), tend to breed on wide expanses of wetlands far from terrestrial predators. They use white to make themselves conspicuous on their territories. Intruding conspecifics can readily see the white residents and easily avoid contact with them and their land. The gray cranes tend to nest on smaller wetland often near uplands. Rather than making themselves conspicuous, these cranes have evolved strategies to hide at the nest. Sandhills and Eurasian, and to a lesser extent black-necked and hooded, apply iron-rich mud to their backs that stains the feathers a reddish-brown color. With the neck lowered while incubating, a painted crane blends with the pile of mud and dead wetland vegetation that constitutes the nest. Undoubtedly, they are much less obvious to predators than are white cranes.

In contrast to the wattled and Grus, the blue and demoiselle cranes often lay their eggs on the ground in grasslands and do not build a nest. These gray cranes are the same color as many weathered rocks and are usually difficult to spot. They nest in a spot that provides a commanding view of the surrounding area. If danger approaches the crane simply stands up and calmly walks away from the nest, making it extremely difficult to pinpoint the location of the eggs.

In South Africa, where gray-crowned, blue, and wattled cranes inhabit the same wetlands and grasslands, the breeding strategies of the three species are easily compared. Crowned cranes nest in dense aquatic vegetation and are usually impossible to see from land. Their strategy is to hide. Blue cranes nest in the short grass and look like a gray stone or if the grass is taller are hidden but for the white-topped head peering above the grass. In contrast, the wattled crane builds a large platform nest in an open area of a small pond in the wetland. The pond, the nest, and the huge crane with a white neck are all conspicuous. The wattled crane makes itself conspicuous to conspecific intruders. Apparently, it is large enough to defend itself from most predators.

Crane eggs vary in color from white to dark brown. Crowned crane eggs appear white from a distance but have a slight blue tint. Sarus and brolgas lay bright white eggs. These species breed in tropical and subtropical areas where temperatures are sometimes so hot that exposure to sunlight is a threat to the survival of the embryo. These cranes must shade their eggs from the sun. The light color of the eggs might help deflect heat from sunlight. In contrast, cranes that breed in the coldest areas (lesser sandhill, Siberian, and black-necked) have the darkest eggs, perhaps an adaptation to absorb more heat from sunlight. The remaining species are intermediate except for the red-crowned crane in which some females lay almost completely white eggs. This leads to speculation that perhaps in prehistoric times, redcrowned cranes might have nested further south in east Asia where heat is more extreme during the breeding season.

Conservation status

Fifteen species survive today and of these, five are considered Vulnerable and six are Endangered.

Whooping crane conservation

In resettlement time, tall grass prairies covered much of the landscapes of what is the "food basket of the world." The deep roots of the prairie grasses built rich soils. Wetlands of the tall grass prairie provided habitat for the whooping cranes. These cranes probably only numbered in the low thousands. For the pioneers, a big bird was a meal, and whooping crane eggs were treasured by egg collectors. The whooping cranes disappeared as a breeding resident from the prairies in 1922.

A remnant flock of whooping cranes survived by breeding in a wilderness wetland area of northern Canada, an area protected within the borders of Wood Buffalo National Park. These cranes migrate about 2,175 mi (3,500 km) to spend the winter along the coast of Texas in Aransas National Wildlife Refuge. The population reached its lowest point in 1941 with just 15 survivors. DNA studies of the pre- and post-bottleneck populations indicate that perhaps as few as three females were breeding when the population was at its lowest. Through widespread public education, the whooping crane became a household word in Canada and the United States. The cranes responded to protection and remarkably their numbers climbed to about 180 birds at the turn of the twenty-first century.

Although a pair of whopping cranes usually lay a clutch of two eggs, they seldom are successful in rearing two chicks. The second egg and later the second chick seem to be for insurance should something happen to the other egg or chick. As a safeguard against extinction, in 1966 the Canadian and U.S. governments established a captive population of whooping cranes by collecting one egg from each of several whooping crane nests. The eggs were taken by air in a

portable incubator to the Patuxent Wildlife Research Center in Maryland. During many springs over the next three decades, eggs were harvested from the wild cranes and taken to captive breeding centers. Today there are about 120 whooping cranes in captivity at three major breeding centers and three zoos.

Banding studies indicate that the whooping crane can breed in its third year, although most breeding first happens when the cranes are 4–5 years old. Population modeling suggests whooping cranes live for 25–30 years if they survive the first few years when mortality is heaviest. One whooping crane might be capable of breeding for more than two decades.

In captivity, whooping cranes usually take 6–8 years before they start breeding. However, whereas wild cranes lay but two eggs per breeding season, captive birds can be induced to lay 6–8 eggs per year if the eggs are removed as they are laid. One pair of captive whooping cranes is capable of contributing 4–6 offspring in a single breeding season. It might take a wild pair of cranes a decade to fledge that number of offspring.

As well as serving as a "species bank," the captive population is also a source of whooping cranes for release programs. The traditional group of cranes that migrates between Canada and the United States faces a variety of threats. The inter-coastal canal traverses the core wetland area used by cranes at the Arkansas National Wildlife Refuge. Barges filled with toxins travel through the refuge every day, and one spill of chemicals could be the demise of most of the whooping cranes. Whooping cranes forage on blue crabs in tidal pools where the salinity is reduced by rainwater and fresh water inflow from inland rivers. Inland stream flow is being blocked for agriculture and urban use. If the salinity of the tidal pools reaches a certain level, the blue crabs become scarce and the cranes are forced to fly to inland oak savanna areas to feed on acorns and other foods. During winters when an adequate supply is not available for the cranes, 6–7 cranes have died. The "old" flock of whooping cranes, although slowly increasing, is by no means secure.

Since 1976, efforts have been made to start new wild populations of whooping cranes using birds reared from eggs collected from the "old" population of wild cranes, and from eggs and birds produced by the captive breeding centers. Between 1976 and 1988, about 300 whooping crane eggs were substituted into the nests of wild sandhill cranes in Idaho. The sandhills raised and migrated with 77 whooping cranes. But unfortunately, the whooping cranes appear to have been sexually imprinted on sandhill cranes. Not a single conspecific pairing occurred. Before the program was discontinued, a mixed pair of sandhill and whooping crane produced a single hybrid—a Whoophill.

In the mid 1980s, ethologist Dr. Robert Horwich developed a remarkable new technique for rearing cranes in captivity known as "costume-rearing." Using this technique, problems associated with sexual imprinting are avoided and birds are reared that are afraid of humans and can be released into the wild. Crane-costumed keepers cloaked in white and wearing a hand puppet that resembles the head of a whooping crane, rear chicks that are exposed to real live whooping cranes in adjacent enclosures.

There was a nonmigratory breeding population in southwest Louisiana that was extirpated in the 1940s. Since 1993, more than 200 costume-reared whooping cranes have been released on the Kissimmee prairie of south-central Florida in an effort to start a nonmigratory population in that area. Bobcat predation has been a major mortality factor.

In 1993, an experiment began in Wisconsin to establish a new migratory population of whooping cranes in eastern North America. Costume-reared cranes were trained to follow ultralight aircraft. Based on preliminary work with sandhill cranes, in which the birds were led south behind an ultralight and returned on their own to natal areas in spring, it is hoped a new and successful migratory population will be established between breeding grounds in central Wisconsin and wintering grounds on the northwest coastal wetlands of peninsular Florida. In the autumn of 2001, 6 whooping cranes migrated south behind the ultralight. Five survived the winter, and all 5 migrated back to Wisconsin without assistance. Finally, whooping cranes might be returned to the rich prairie wetlands of the great plains.

Siberian crane conservation

The Siberian crane shares many threats with the whooping crane. Both species breed in the far north of respective continents; both species migrate across a continent; and both species must use wetlands that occur near heavily populated areas. But while the whooping crane has only one population, the Siberian crane has three—all of which breed in Russia. One group migrates from western Siberia to Iran. A second group breeds 620 mi (1,000 km) due north of the first group and migrates to India. A third group breeds on the tundra of eastern Siberia and winters in China. The western group numbers fewer than 12 birds. The central group has declined during recent decades from 75 birds to a single pair. The eastern group numbers approximately 3,000.

Prior to massive public education along the flyway through the heart of North America, many whooping cranes were probably shot. Hunting remains a problem along flyways used by Siberian cranes in west Asia. And just as the conservation along the coast of Texas is vital to the survival of whooping cranes in winter, the conservation of wetlands in Iran, India, and China is vital to the conservation of the Siberian crane. Whooping crane management is based on the comparatively well-funded activities of specialists in Canada and the United States. Funds for Siberian crane management are extremely limited, and 12 nations (Afghanistan, Azerbaijan, China, India, Iran, Kazakhstan, Pakistan, Russia, Turkmenistan, Uzbekistan) must participate if the three populations of Siberian cranes are to be maintained and/or restored.

In 1976, Russian ornithologist Dr. Vladimir Flint, in collaboration with the U.S.-based International Crane Foundation (ICF), began a major program for the conservation of the Siberian crane. Hatching eggs were transported from the tundra breeding grounds of eastern Siberia to ICF and the Oka Nature Reserve south of Moscow. A flourishing captive population has been established and many eggs and birds are available for release programs.

In 1978, Iranian ornithologists discovered the remnant population of Siberian cranes in the Caspian lowlands. The cranes spend the winter inside a waterfowl trapping complex where shooting is banned. It was not until 1996 that Russian scientists discovered their breeding grounds west of the town of Uvat in southwest Siberia.

The year 1981 was a banner year for the Siberian crane. That year the breeding grounds of the central population were discovered on the basin of the Kunovat River in western Siberia, the wintering grounds of the eastern population were discovered at Poyang Lake, China, and the species bred for the first time in captivity.

Although the well-known Keoladeo National Park in India provided sanctuary for the central population of Siberian cranes, winter counts in India show a steady decline of cranes, presumably as a result of hunting along the 3,100 mi (5,000 km) migration route. The breeding area of the central population has been protected both for the cranes and for the indigenous local people, the Khanty, some of whom continue to live a traditional lifestyle.

The eastern population holds the largest share of the Siberian cranes. The major breeding area in Russia has been protected as Kytalic Nature Reserve, while the major wintering area in China has been protected as Poyang Lake Nature Reserve. Likewise, several important wetlands in northeast China have been conserved to protect breeding habitat of redcrowned and white-naped cranes and migration staging areas for Siberian cranes. However, there are concerns that water diversion projects in China, designed to meet the needs of humans, might negatively impact wetlands vital to the welfare of the eastern population.

In 1993, the Convention for Migratory Species headquartered in Bonn, Germany, developed, in collaboration with ICF, a Memorandum of Understanding on the Conservation of the Siberian Crane. This agreement has been signed by most of the range states. Every two years delegates from the range states meet to report on conservation actions and to refine recovery programs for the three populations of Siberian cranes.

A number of experiments have been undertaken to augment the western and central populations, but as yet none have met with confirmed success. Several captive-reared cranes released with the wild cranes in India and Iran failed either to join the wild cranes or to migrate. Although scientists have not confirmed the survival of captive-reared Siberian cranes released with wild cranes on the breeding grounds of the wild Siberian cranes, and on the migration staging areas of Eurasian and Siberian cranes in Western Russia, local people near the release areas have reported in subsequent years the presence of color-banded Siberian cranes. Now Russian scientists are exploring the possibility to leading captive-reared Siberian cranes south behind hang gliders, rather than behind ultralight aircraft as is being done in North America for whooping cranes.

Significance to humans

Humans have been intrigued by the grace and beauty of cranes since ancient times. Today they are a symbol of good luck in many parts of the world, and appear on coins and as national symbols. The whooping crane is a special conservation symbol in North America, because of its recovery from the brink of extinction.

Species accounts

List of Species

Gray crowned crane

Balearica regulorum

subfamily

Balearicinae

taxonomy

Arthropoïdes regulorum Bennett, 1834, South Africa. Two subspecies.

other common names

English: Blue-necked crane, royal crane; French: Grue royale; German: Südafrikanischer kronenkranich; Spanish: Grulla Coronada Cuelligrís.

physical characteristics

Height 39–43.3 in (100–110) cm; wingspan 71–79 in (180–200 cm); weight 6.6–8.8 lb (3–4) kg. Distinctive crown of gold feathers. Pale gray neck and red throat wattles.

distribution

Eastern Africa from Kenya to South Africa, west to Zambia, also Angola and Namibia.

habitat

Uses wetlands and grasslands or savanna.

behavior

These birds perch in trees and use ground nests, or rarely tree nests, abandoned by other large birds.

feeding ecology and diet

Wide range of food preferences, including seeds and insects.

reproductive biology

Breed in wetland-grassland areas.

conservation status

Not threatened. The most abundant crane in Africa, though populations have declined. Continued wetland drainage may threaten its future, as many live and forage outside of protected areas.

significance to humans

Gray-crowned cranes are the national bird of Uganda and regarded as a sacred bird or symbol in Kenya, Namibia, South Africa, and Zambia.

Demoiselle crane

Anthropoides virgo

subfamily

Gruinae

taxonomy

Ardea virgo Linnaeus, 1758, India. Monotypic.

other common names

French: Grue demoiselle; German: Jungfernkranich; Spanish: Grulla Damisela.

physical characteristics

Height 35.4 in (90 cm); wingspan 59–67 in (150–170 cm); weight 4.4–6.6 lb (2–3 kg). All gray, but with black neck and head, and white ear tufts behind eye to upper neck.

distribution

Eastern Europe across central Asia to eastern China. Small populations in Morocco and Turkey. Winter in Africa, Pakistan, and India.

habitat

Grassland near streams or other wetlands.

behavior

Aggressively defend their nesting sites.

feeding ecology and diet

Generally grass seeds and other plant materials; also some insects, worms, lizards, and other small vertebrates.

reproductive biology

Eggs are laid in nests made of pebbles, or laid on the ground, in upland or desert areas with some vegetation to hide the incubating parent.

conservation status

Not threatened, though listed on CITES Appendix II. Legally protected in many countries.

significance to humans

Good luck symbols in Mongolia and parts of India, and generally revered in Islamic countries.

Wattled crane

Bugeranus carunculatus

subfamily

Gruinae

taxonomy

Ardea carunculata Gmelin, 1789, Cape of Good Hope. Monotypic.

other common names

English: Great African wattled crane; French: Grue caronculée; German: Klunkerkranich; Spanish: Grulla Carunculada.

physical characteristics

Height 69 in (175 cm); wingspan 90.5–102.3 in (230–260) cm; weight male 18.3–18.7 lb (8.3–8.5 kg), female 15.6–17.4 (7.1–7.9 kg). Body and wings gray and black, white neck, wattles white with some red skin.

distribution

South-central Africa, with some populations in Ethiopia, South Africa, Namibia, and in the Zambezi Delta on Africa's east coast.

habitat

Dependent on wetlands.

behavior

Nonmigratory. Rarely leave their territories.

feeding ecology and diet

Their primary food is sedge tubers, which they find in shallow wetlands.

reproductive biology

Many nests contain only a single egg. Incubation lasts up to 40 days, and the fledgling period is 103 days or more.

conservation status

Endangered, and listed on CITES Appendix II. Protected throughout much of their range.

significance to humans

These birds receive great attention in South Africa as one of the nation's most endangered birds.

Siberian crane

Grus leucogeranus

subfamily

Gruinae

taxonomy

Grus leucogeranus Pallas, 1773, central Siberia. Monotypic.

other common names

English: Great white crane, Siberian white crane, Asiatic white crane; French: Grue de Sibérie; German: Schneekranich; Spanish: Grulla Siberiana.

physical characteristics

Height 55 in (140 cm); wingspan 82.6–90.5 in (210–230 cm); weight 11–19 lb (5–8.6 kg). White crane with dark red mask around bill and eyes. Serrated bill tip.

distribution

Russia; winters in China, Iran, and India.

habitat

Uses wetlands for nesting, breeding, and roosting.

behavior

Migrate long distances over international borders.

feeding ecology and diet

During winter and while migrating, the cranes feed on tubers. While nesting, they feed on invertebrates, cranberries, frogs, mollusks, aquatic insects, and fish.

reproductive biology

Usually lay 2 eggs, incubated for 29 days. Chicks fledge at 70–75 days.

conservation status

Endangered, and listed on CITES Appendix I. Strict dependence on wetlands makes it susceptible to habitat loss due to development, dam building, and oil exploration.

significance to humans

Revered by Khanty people in western Siberia and Yakatian people in eastern Siberia. Treasured as "Lily of Birds" by Indians.

Sandhill crane

Grus canadensis

subfamily

Gruinae

taxonomy

Ardea canadensis Linnaeus, 1758, Hudson Bay, Canada. Six subspecies.

other common names

English: Little brown crane, Canadian crane; French: Grue du Canada; German: Kanadakranich; Spanish: Grulla Canadiense.

physical characteristics

Height up to 47.2 in (120 cm); wingspan 63–82.6 in (160–210 cm); weight 7.3–12 lb (3.3–5.4 kg). Gray body, neck, and head with bare red forecrown.

distribution

Across North America from Quebec west to British Columbia and north to Alaska and eastern Siberia. Additional populations in Pennsylvania, Ohio, Maine, and the Northwest (U.S.). Winter in Florida, Texas, New Mexico, Arizona, California, and Mexico. Nonmigratory subspecies found in Florida, Mississippi, and Cuba.

habitat

Wetland areas. May use savannas and agricultural fields in wintering areas.

behavior

Three subspecies are migratory; three are nonmigratory.

feeding ecology and diet

Omnivorous. Diet includes grains, berries, insects, and rodents.

reproductive biology

Usually lays 2 eggs, incubated for 29–32 days. Chicks fledge at 50–90 days.

conservation status

Four subspecies Not threatened, though listed on CITES Appendix II. Two subspecies, the Mississippi and the Cuban sandhill, are Threatened.

significance to humans

The most abundant of all cranes, it has been a part of Native American culture for over 1,000 years.

Sarus crane

Grus antigone

subfamily

Gruinae

taxonomy

Ardea antigone Linnaeus, 1758, India. Three subspecies.

other common names

English: Sharpe's crane; French: Grue antigone; German: Saruskranich; Spanish: Grulla Sarus.

physical characteristics

Height up to 69 in (176 cm); wingspan 86.6–110.2 in (220–280 cm); weight 11–26.5 lb (5–12 kg). Gray body, red skin on head, throat, and upper neck.

distribution

Northern and central India, southeastern Pakistan, southern Myanmar, Cambodia, southern Laos, Vietnam, and northern Australia.

habitat

Wetlands, including seasonally flooded savannas and human-made areas such as canals, irrigation ditches, and fields.

behavior

Subspecies in India and Australia is generally nonmigratory, but population in southeast Asia is locally migratory.

feeding ecology and diet

A generalist, its diet includes plants, grains, insects, fish, and other small vertebrates.

reproductive biology

Lays 2 or 3 eggs, incubated for 31–34 days. Chicks fledge at 85–100 days.

conservation status

Endangered, and listed on CITES Appendix II.

significance to humans

Regarded as omens for good crops in India.

Eurasian crane

Grus grus

subfamily

Gruinae

taxonomy

Ardea grus Linnaeus, 1758 Sweden. Monotypic.

other common names

English: Common crane; French: Grue cendrée; German: Kranich; Spanish: Grulla Común.

physical characteristics

Height 45 in (114 cm); wingspan 71–78.7 in (180–200 cm); weight male 11–13.4 lb (5–6.1 kg), female 10–13 lb (4.5–5.9 kg). Gray body with black primaries. Head and neck are dark with white stripe from behind eyes down neck. Crown has red skin patch.

distribution

The most widely distributed of all cranes, they occupy an area extending across the Scandinavian countries south to Germany and then east to eastern Russia and China. Winter in Spain, northern Africa, the Middle East, India, Indochina, and China.

habitat

Shallow wetlands. In winter range, it may forage in agricultural fields and pastures.

behavior

Migrates throughout Asia, Europe, and northern Africa.

feeding ecology and diet

Omnivorous, including tubers, stems, leaves, berries, and other plant material; also invertebrates (worms and insects) and some small vertebrates (snakes, fish, rodents).

reproductive biology

Typically lays 2 eggs, incubated for 28–31 days. Chicks fledge at 65–70 days.

conservation status

Not threatened, though listed on CITES Appendix II. Its habitat would benefit from increased protection in heavily populated areas of Europe.

significance to humans

Their yearly return to the Scandinavian countries is heralded as a sign of spring.

Whooping crane

Grus americana

subfamily

Gruinae

taxonomy

Ardea americana Linnaeus, 1758, Hudson Bay, Canada. Monotypic.

other common names

English: Whooper, big white crane; French: Grue blanche; German: Schreikranich; Spanish: Grulla Trompetera.

physical characteristics

Height 5 ft (150 cm), wingspan 7–8 ft (200–230 cm). Weight: male 16 lb (7.3 kg), female 14 lb (6.4 kg). White with black wingtips, legs, and feet; black facial markings; and a bare patch of red skin on its head.

distribution

Wood Buffalo National Park in west-central Canada; winters at Aransas National Wildlife Refuge on the Gulf Coast of Texas.

habitat

Currently use ponds and marshes; historically used potholes and other wetlands of North American plains and prairies. Winter habitat includes coastal marshes.

behavior

Wild flock is migratory, as well as an experimental flock in the Rocky Mountains. An experimental flock in Florida is nonmigratory, and has dispersed from its original release area.

feeding ecology and diet

Omnivorous, its diet includes blue crabs, small fish, rodents, berries, tubers, grain, insects, and other invertebrates.

reproductive biology

Whooping cranes are monogamous. Both parents take turns incubating two eggs for a period of 29–30 days. Both eggs may hatch, but usually only one chick survives the first few months to reach fledging age.

conservation status

Endangered, and listed on CITES Appendix I.

significance to humans

After near extinction and subsequent precarious recovery, it has become a symbol of conservation in North America.

Red-crowned crane

Grus japonensis

subfamily

Gruinae

taxonomy

Ardea (Grus) japonensis P.L.S. Müller, 1776 Japan. Monotypic.

other common names

English: Japanese crane, Manchurian crane; French: Grue du Japon; German: Mandschurenkranich; Spanish: Grulla Manchü.

physical characteristics

Height 59 in (150 cm); wingspan 86.6–98.4 in (220–250 cm); weight 15.4–22 lb (7–10 kg). White body with black neck and white nape. Red skin on crown.

distribution

Most breed in the Amur River basin near the China-Russia border and winter in coastal areas of China and on the Korean peninsula, many within the Korean Demilitarized Zone (DMZ). A nonmigratory population remains year-round on Hokkaidō Japan.

habitat

More aquatic, using marshes and other deep wetland areas. Winter habitat includes rivers, freshwater wetlands, and coastal salt-marshes.

behavior

Well-known for their elaborate courtship dances.

feeding ecology and diet

A generalist, it feeds on insects, fish, rodents, and plants.

reproductive biology

Lays 2 eggs, incubated for 29–34 days. Chicks fledge at about 95 days.

conservation status

Endangered, and listed on CITES Appendix I.

significance to humans

The "sacred crane" is widely revered in the Orient as a symbol of fidelity in marriage, good luck, long life, and love. These cranes are often the subjects of poems, mythology, and art.

Resources

Books

Archibald, G.W. "Cranes and their Allies." In Encyclopedia of Birds: A Comprehensive Illustrated Guide by International Experts, 2nd ed. Edited by Joseph Forshaw. Sydney: UNSW Press Ltd., 1998.

del Hoyo, J., A. Elliott, and J. Sargatal. Handbook of the Birds of the World. Vol. 3, Hoatzin to Auks. Barcelona: Lynx Edicions, 1996.

Meine, Curt D. and George W. Archibald, eds. The Cranes: Status Survey and Conservation Action Plan. Cambridge: IUCN Publication Services, 1996.

Sibley, C.G., and B.L. Monroe, Jr. Distribution and Taxonomy of Birds of the World. New Haven: Yale University Press, 1990.

Periodicals

Horwich, Robert H. "Use of Surrogate Parental Models and Age Periods in a Successful Release of Hand-Reared Sandhill Cranes." Zoo Biology 8 (1989): 379–90.

Krajewski, Carey. "Phylogenetic Relationships Among Cranes (Gruiformes: Gruidae) Based on DNA Hybridization." Auk 106 (1989): 603–18.

Wessling, Bernhard. "Individual Recognition of Cranes, Monitoring and Vocal Communication Analysis by Sonography." IV European Crane Workshop. European Crane Working Group, 2000.

Organizations

International Crane Foundation. P.O. Box 447, Baraboo, WI 53913-0447 USA. Phone: (608) 356-9462. Fax: (608) 356-9465. E-mail: [email protected] Web site: <http://www.savingcranes.org>

George William Archibald, PhD