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Cranes: General Questions
Q: How many kinds of cranes are there, and how many does ICF have?
A:
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?
A: 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?
A: Whooping cranes are the least common crane species. Red-crowned cranes are the second rarest crane species.
Q: What predators might prey on cranes?
A: 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?
A: Many species of cranes are hunted for food or sport.
Flight and Migration
Q: How far and how high do cranes fly?
A: 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.
Senses
Q: How good is the vision of a crane?
A: 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?
A: 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.
Size
Q: How much do cranes weigh?
A: 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?
A: From five to eight feet, depending on the species.
Behavior
Q: Why do cranes stand on one leg?
A: 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?
A: 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?
A: 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.
Feeding
Q: What do the cranes at ICF eat?
A: 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?
A: 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?
A: 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?
A: 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?
A: 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?
A: 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?
A: 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?
A: 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?
A: 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?
A: 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?
A: 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?
A: 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?
A: 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?
A: 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?
A: About 50%.
Q: How many of the fertile eggs hatch?
A: 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?
A: About 85-90%.
Q: How big are crane eggs?
A: 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?
A: 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?
A: 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: 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?
A: If a mate is lost, the remaining bird will usually find another partner.
Q: How old are cranes before they mate?
A: 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?
A: 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.
Health
Q: What is the process for moving eggs or birds?
A: 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?
A: 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?
A: 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?
A: 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: What else are crane chicks called?
A: Crane chicks are also known as "colts".
Site
Q: How many people visit ICF each year?
A: 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?
A: 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?
A: We currently have about 225 acres.Much of it (about 100 acres) is restored prairie and oak savanna.
Q: What is Crane City?
A: "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?
A: 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?
A: 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?
A: 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?
A: 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?
A: 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.
Organization
Q: How many people work here?
A: 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?
A: 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.
Careers
Q: If I'm interested in working with cranes as a career, what course of study is recommended?
A: 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
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