Cranes: General Questions
Q: How many kinds of cranes are there, and how many does ICF have?
There are 15 species in the crane family Gruidae. According to the conservation status designations assigned by ICF, six of the species are considered endangered. These are the blue, red-crowned, sarus, Siberian, wattled, and whooping cranes. ICF classifies another five species as vulnerable, including the black crowned, black-necked, grey crowned, hooded, and white-naped cranes. We have all 15 species of cranes at ICF. The total number of cranes we have varies from season to season, but we normally have between 100-120 birds. We typically have up to 30 birds on display in the Wattled Crane Exhibit, Johnson Exhibit Pod, and Whooping Crane Exhibit, with approximately 70 additional birds housed in Crane City.
Q: Why does ICF recognize 15 species of cranes?
Some researchers believe there are only 14 species (they place the two African crowned cranes together as a single species). Other researchers may argue that there are more than 15 species (they “split” the crowned cranes into as many as four species). We believe there are enough genetic differences to justify naming two species of crowned cranes, but not enough differences to recognize four.
Q: Which crane is the rarest?
Whooping cranes are the least common crane species. Red-crowned cranes are the second rarest crane species.
Q: What predators might prey on cranes?
Crane predators vary from place to place since cranes live on so many of the continents. In the United States, animals such as raccoons, fox, and bears may prey on the eggs or young. Wolves prey on unfledged whooping cranes at Wood Buffalo National Park. Adult cranes can usually escape these predators, but cannot escape large birds of prey such as golden eagles. The crane’s large size, aggressive disposition, and its ability to fly provide protection from predators. Humans are the most dangerous predator of cranes. Direct predation occurs in the form of hunting. Twelve western states in the U.S. have hunting seasons on sandhills, along with two Canadian provinces. Furthermore, there is some subsistence hunting in Mexico and Russia, as well as in some areas in Asia. Indirect influences, more difficult to guard against, include disturbance and habitat loss.
Q: Why are cranes hunted?
Many species of cranes are hunted for food or sport.
Flight and Migration
Q: How far and how high do cranes fly?
Siberian cranes migrate nearly 10,000 miles round trip. Cranes usually fly at an altitude of 3,000-5,000 feet, although they must fly much higher than that as they pass over mountain ranges.
Q: How good is the vision of a crane?
Visual acuity is difficult to determine, because seeing something depends on several conditions. For instance, some birds see some colors better than humans can. Color discrimination allows birds to find preferred foods more quickly. Birds often look for certain shapes or patterns. As an example, cranes will often see large predatory birds long before we do, but they are deliberately looking for them while we are not. In addition, we rarely think of eyesight as an adaptation for flight, but birds, including cranes, require excellent eyesight to fly.
Q: Do cranes have a sense of smell?
Perhaps. Studies show that some families of birds, including cranes, have enlarged olfactory sense centers in the brain. However, our experience shows that cranes rely on hearing and vision rather than the sense of smell to detect food, other cranes, or enemies.
Q: How much do cranes weigh?
Demoiselle cranes, the lightest species, weigh about five pounds, and red-crowned cranes, the heaviest, weigh up to 26 pounds.
Q: What is their wingspan?
From five to eight feet, depending on the species.
Q: Why do cranes stand on one leg?
They stand on one leg when they are roosting, and tuck one leg up into their body to keep it warm. Birds, like mammals, are warm blooded. Because cranes have higher temperatures and smaller bodies than humans, they lose body heat more readily.
Q: What is a precocial bird?
Precocial chicks, like cranes and other ground-nesting birds, are those which hatch with down feathers, open eyes, and the ability to leave the nest within hours of hatching. Songbirds are altricialthey hatch naked and blind, and are dependent on their parents for food.
Q: What is imprinting?
Imprinting is a rapid learning process which takes place in young precocial birds. Imprinting occurs when young birds follow and identify the first large moving object they see as a parent. They learn their parents’ behavioral and physical characteristics and gain impressions which remain with them for life. The process of imprinting is still not well understood. For instance, there are probably several stages of growth where imprinting is important. There is parental imprinting, when the chick determines its species; but also sexual imprinting, where the chick determines what it will seek for a mate as it matures.
Q: What do the cranes at ICF eat?
At ICF, cranes eat “crane chow”, a special blend of soy, alfalfa, fish, and corn meal, with a special vitamin supplement. All species get the same diet, although protein content changes with the season and the bird’s age. Breeding females also get calcium chips in spring to help with eggshell formation, and all the cranes get shelled corn in winter, to provide extra carbohydrates.
Q: Do cranes cause crop damage?
Yes, on occasion they will. In Wisconsin, cranes may cause crop damage in corn and potato fields, where the birds may feed on newly sprouted corn plants or maturing potato tubers. Members of the ICF Field Ecology Department are involved in a long-term study of crop depredation in a study area located near Briggsville, Wisconsin. ICF researchers are working with local farmers to develop a substance to put on corn kernels that will taste bad to cranes, with the hope that this will deter them from feeding in treated fields. Farmers throughout the world are faced with this challenge, and solutions developed in Wisconsin may be useful for farmers in other countries.
Q: Do chicks know how to eat when they are hatched?
No. In the wild, crane chicks follow their parents and are fed by them. Chicks peck food from their parents’ beaks. When the crane chicks are two to three months old, they are very independent, pecking and probing on their own, and finding food items by trial and error. Occasionally, the parents may still present new food items to the chicks. Feeding the chick may help keep the bond between the chicks and parents strong during the migration and wintering season.
Q: What do wild chicks eat?
Crane chicks eat mostly insects during the spring, since their fast growth requires high-protein foods. Later in the summer, they will begin to feed on larger animals along with roots and tubers.
Growth and Development
Q: How fast do crane chicks grow?
Crane chicks grow very rapidly up to an inch per day some days, or five feet in three months. Some growing crane chicks can put on almost one pound of weight for every pound of food they eat. In the wild, crane chicks may gain up to 20% of their body weight per day, however, we limit them to about 10% per day at ICF.
Q: When do the chicks get feathers, and when do they fledge?
Crane chicks hatch with down feathers, which are replaced in about two months as their cinnamon-colored juvenile plumage grows out from the base of the same feather. In turn, the juvenile plumage is molted, and is followed by the first winter plumage (gray or white, depending on the species). This winter plumage is usually replaced the following year. Most adults molt at least once per year, after the breeding season. Ten species of cranes are flightless during the wing feather molt because they lose most of their flight feathers all at once. Crane chicks usually fledge, or acquire the feathers necessary for flight, when they are about three months old.
Q: How long do the chicks stay with their parents?
The chicks usually stay with the parents less than a year. Sandhill crane chicks separate from their parents during the spring migration, or are driven off as the pair establishes their breeding territory.
Q: How long do cranes live?
Approximately 20-30 years in the wild and up to 80 years in captivity.
Eggs and Reproduction
Q: How many eggs do cranes usually lay? Is it only in spring?
Cranes usually lay two eggs. However, the crowned cranes may lay two to five eggs in a single clutch while the wattled cranes may lay only one egg. Cranes that nest in the north will nest in the spring. Those that live in more tropical areas have a less restricted breeding season. Florida sandhills may nest in any one of six months, while the greater sandhill has a much more restricted breeding season of only about two months. Cranes that live south of the equator adapt somewhat to our northern latitudes at ICF by nesting in late spring or summer.
Q: How many eggs does a female lay?
In the wild there are normally two eggs in a clutch. At ICF we sometimes take the eggs away as soon as they are laid. The female then lays more eggs, an adaptation known as “double clutching.” As many as 19 eggs have been produced by one female during a breeding season (Pasque, 1988). We limit each female to five to six eggs per year to avoid unnecessary stress.
Q: Why do they lay two eggs, when usually only one chick survives?
Migration, territory defense and breeding are difficult, energy-consuming activities that place the adults at risk. If cranes only laid one egg and it was infertile, or the chick died, the birds have expended that energy in a futile effort. The second egg could be considered insurance against failure. In years when food is abundant, both chicks may survive.
Q. How do you limit the number of eggs a female lays in a season?
Cranes will stop laying eggs once they have two eggs in the nest. To stop a female from laying, we leave the last two eggs we want her to lay. Sometimes we give the crane pair fake eggs, or dummy eggs, so they will stop laying and start incubating an egg that will not develop. But some of the birds can tell the difference and will sometimes destroy the fakes!
Q: How many eggs are laid in an average breeding season at ICF?
At ICF, about 130 to 150 eggs will be produced during a typical breeding season. Not all of these eggs are allowed to hatch. We want all the birds to breed and lay eggs, because it is important for their normal development. Being a good parent takes practice, and we want good crane parents. Once these “practicing” parents become good incubators, they sometimes are given more “important” eggs from endangered species, such as Siberian or whooping cranes, to incubate. The pair’s original egg(s) are not allowed to develop. Each year we select certain species with which to work.
Q: How old are cranes when they first breed?
Most species mature and begin breeding in captivity at three years of age. In the wild, we think cranes are at least four to five years old before they nest successfully. Some species, like the Siberians, may take even longer-up to six or seven years.
Q: How many of the eggs laid at ICF are fertile?
Q: How many of the fertile eggs hatch?
About 70% over the past 15 years. However, we do not try to hatch all of the eggs that are fertile. We want all of our pairs to behave as naturally as possible, and that includes breeding and laying eggs. But we have specific goals on which eggs we want to hatch. We are also members of four Species Survival Plans (SSPs). Each plan is governed by a committee that sets breeding goals for pairs of a particular species held by member institutions. Since some pairs are easier to breed than others, the committee makes sure that one pair’s genetics will not become overrepresented in the captive population. In some instances, we are not allowed to hatch the eggs of some of our pairs, because those pairs are already well represented.
Q: How many of the chicks at ICF survive to fledging?
Q: How big are crane eggs?
The size of a crane egg depends on the species. The larger the crane, the larger the egg. The largest of crane eggs will be about 4.6 inches long. They are usually tan with brown speckles.
Q: If you take eggs, will the cranes lay more?
Yes. “Double clutching” is one of the primary justifications for keeping these slowly-reproducing birds in captivity. One sandhill pair once laid 19 eggs in a single season, but we usually want a pair to lay only 5-6 eggs so the female is not unduly stressed.
Q: Do cranes ever select a mate from another species?
On rare occasions in the wild, brolgas have paired with sarus cranes, and Eurasians have paired with hooded cranes. Their offspring are fertile. We do not crossbreed species.
Q: What is the male’s role while waiting for eggs to hatch?
A male will also incubate the eggs, but his primary task is to maintain the integrity of the territory. Incubating pairs trade places about every two hours during daylight hours. This gives each bird a chance to stretch, exercise, and feed. At night, the female incubates while the male stands guard. The male is often the first to feed the chicks.
Q: Cranes mate for life. What happens if one dies?
If a mate is lost, the remaining bird will usually find another partner.
Q: How old are cranes before they mate?
It varies, but typically cranes are several years old before they begin breeding. In captivity, about three years old; in the wild, about four to five years old. Siberian cranes may not breed until they are seven years old.
Q: What do you do with crane eggs that are infertile?
Often, we use infertile eggs to make “dummy eggs.” We make a small hole in one end of the egg and blow out the contents, then fill the egg with plaster. This makes it a bit more durable than an empty shell. Dummy eggs are used by our CCD Department to give inexperienced cranes practice incubating. These eggs are also used by our Education Department for hands-on learning, or sent out to museums or researchers.
Q: What is the process for moving eggs or birds?
Eggs are moved in foam-lined, heated boxes. Plastic gloves are worn when eggs are handled to protect the shells from skin oils. Cranes are shipped in specially designed crates that are large enough so the birds can either stand or lie down, but not large enough for them to open their wings. Mated pairs are shipped in larger crates so they are in visual and vocal contact, although separated by a partition. The size and construction of the crate is important in reducing the possibility of the bird being injured.
Q: Do cranes get deer ticks?
Each October, we conduct an annual health check which includes a check for external parasites such as ticks. We have found few wood ticks on the birds. There are also deer ticks on our site, so remember to do tick checks after walking our trails.
Chick Rearing Techniques
Q: What are isolation pens?
They are pens in which chicks are isolated from all human contact. Chicks raised in isolation pens are fed by a crane puppet through an opening in the door, and exercised by a human disguised as a crane; they hear only other cranes, either on tape or in the pen next door. These birds may later be introduced to wild flocks of cranes where they learn additional survival skills.
Q: Why do you raise cranes in isolation from humans?
There are two main reasons why we rear chicks in isolation:
1. Birds for release: Birds raised in isolation from humans are better adapted for living in the wild. Using the “soft release” method, we may be able to help increase the numbers of cranes in wild flocks. This method was tested on migratory greater sandhill cranes in Wisconsin and in Michigan and in our Florida release program. Note: Parent-reared birds may also be released into the wild. This has been successful in increasing the non-migratory flock of Mississippi sandhills. Mississippi sandhill chicks were reared by sandhill cranes at Patuxent Wildlife Research Center, and later released successfully.
2. Birds for captivity: Some species are more prone to imprinting on people than others (e.g. Eastern sarus cranes). These birds are reared in isolation before being exposed to humans. Exposure to humans is necessary or the chicks may be afraid of people. If afraid, the birds may injure themselves while trying to get away from people.
Q: How many people visit ICF each year?
Approximately 25,000 people visit each year. In addition, we reach thousands of people each year through our website, international programs, and off-site programming.
Q: Why did you move from the old site?
The people who let us use the old site, Norman and Claire Sauey, wanted to use the farm again themselves. In addition, at the old site the birds and staff were getting overcrowded. In the early 1980s, we relocated to our present location on Shady Lane Road just a few miles north of Baraboo, WI.
Q: How much land do you have here?
We currently have about 225 acres.Much of it (about 100 acres) is restored prairie and oak savanna.
Q: What is Crane City?
“Crane City” is the breeding area at the back of the property, which now consists of 65 pens. It is off-limits to the public, since breeding cranes are sensitive to disturbance from people.
Q: Do you have any problems with predators?
Until 1982, we had very few problems. In June of 1982, raccoons climbed the fence of the crane pens, chewed through the nylon flight netting, and dropped into the yards. Tex, the famous whooping crane, was the first bird killed. Patrols, traps, blaring radios, and an electric fence did not stop the raccoons, and five cranes died that summer. Now we have electrified wires on top of the perimeter fences. They are effective in stopping predators. The fences are also buried two feet underground to prevent dogs, foxes, and coyotes from digging underneath. During the winter of 1989-90, we lost four cranes to a mink that could wiggle through the two-inch mesh fence on the pens. Now each winter, when the mink are most active, we install a temporary one-inch mesh poultry wire over the fronts of the pens.
Q: How powerful is the electric fence?
There is not enough power in the fence to injure predators. But even large animals, like raccoons, are surprised by the jolt they get when they touch these fences.
Q: Are there any other institutions with cranes in captivity?
Many zoos and research centers have cranes, but ICF has the most complete collection. ICF is also the only place making a coordinated and comprehensive effort to save critical habitat, propagate cranes in captivity, reintroduce them to the wild, and educate people living nearby about their relationship to wetlands and cranes.
Q: Who names the cranes at ICF?
Generally the CCD staff names them. Sometimes they are named after people (Dr. Saab), or geographic locations (Aransas), others are named after cultural attributes (Haiku-a form of Japanese poem).
Q: What do the cranes at ICF do in the winter?
The Wisconsin winter is similar to conditions in the wild for several of the cranes. Species which are sensitive to the cold are locked indoors at night or for the cold season. Some of the cranes have small heaters to warm their indoor quarters.
Q: How many people work here?
There is over 30 permanent staff, along with many student interns each year, seasonal naturalists, seasonal employees in the Gift Shop, several graduate students, and several dozen volunteers. To find out about employment opportunities, visit our website.
Q: Where does your funding come from?
Much of ICF’s support is from private sources such as grants, donations from individuals or companies, and membership donations. Entrance fees and income from the gift shop also help. The federal government pays us a yearly stipend to take care of each whooping crane kept here.
Q: If I’m interested in working with cranes as a career, what course of study is recommended?
ICF staff members have various backgrounds and levels of education and experience. Aviculturists and Field Ecologists have biology backgrounds, while medical technicians and veterinarians have more specific fields of study. Education staff members have backgrounds in management, environmental education, computers, writing, teaching, etc