Raising Cranes

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A costumed biologist interacts with young Whooping Cranes hatched in captivity.

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What does it take to raise a crane in captivity? Experienced and dedicated staff, healthy cranes, and time. When any species is first brought into captivity, it takes trial and error to figure out how to keep the individuals healthy and reproduce successfully. Raising cranes in captivity takes a huge amount of effort (as noted below). However, when wild populations are at great risk, such as with the Whooping Crane, captive breeding has been an essential part of saving an endangered species from disappearing in the wild.

Crane Chick CamJoin us for our monthly Chick Chats with ICF’s aviculture staff. Click here to request an email reminder for our upcoming chats or replay any of our past chats.

Tex's Legacy

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Tex and George Archibald

In the mid 1970s the "Tex" was the only surviving chick of Whooping Cranes taken from the wild when the population was very low. Biologists working with Tex knew that she likely had rare genes found in no other Whooping Crane - genes that could help future Whooping Cranes fight off disease or adapt to new conditions.

But the human-reared Tex was hopelessly imprinted on people and would not mate with another Whooping Crane. How did we get Tex to breed? View George & Tex for the answer...

socializationMatchmaking

A strong pair bond is essential in captive breeding.  ICF’s staff act as matchmakers when pairing captive cranes. We select pairs based on the individual’s genetics, behavior, age, and rearing history to create the best match. Due to the Whooping Crane’s low population in the 1940s, genetics play a very important role in the matchmaking process for this species.

Once individual cranes are identified as a “good match,” the socialization process begins. Socializing a pair can vary in length from a few months to several years based on the birds’ initial attraction to each other. The formation of a strong pair is critical to a successful breeding program, because often a female will not become capable of producing eggs until she has formed a strong bond with her mate.  The Whooping Crane pair shown at left, Achilles and Aransas, took 3+ years to socialize and are a very genetically valuable pair. 

Initial socialization sessions are brief and monitored closely by staff via remote cameras. We look for synchronized preening, roosting, dancing, and unison calling. As the birds become more comfortable with each other, elements are introduced that the cranes may exhibit aggression over, such as food and water.  If the birds are interacting well, they are left together overnight. If they continue to get along after their first night together, they may remain together permanently. Staff continue to monitor the pair, especially as the birds come into their first breeding season together.  

Eggs!

Nest building and egg laying generally begins in mid to late April for Whooping Cranes and continues through early June. Whooping Cranes typically have a two egg clutch, with the second egg laid two to three days after the first. In the wild, a pair would begin incubating and attempt to hatch and rear both eggs in the clutch. However, in captivity we have the option of multiple clutching - eggs are retrieved from the nest as they are laid or as a clutch is completed. By not allowing the pair to incubate, they will be stimulated to produce another clutch of eggs, thereby increasing the number of eggs available for reintroduction programs. Staff look at an individual female’s age, health, and laying history to determine the number of eggs each crane can lay.

By the time breeding season arrives, staff are preparing to begin artificial insemination (AI) on many of the pairs. AI is used to manage for genetic diversity and to increase egg fertility. Since we can do AI on individuals from different pairs, strongly bonded pairs can remain together even if they are not a good genetic match. AI can also result in higher fertility rates than natural mating - birds with clipped wings or leg problems, such as arthritis, may have difficulty copulating naturally, so AI becomes essential. 

Once the desired number of eggs has been reached for the reintroduction programs, many Whooping Crane pairs are given the opportunity to incubate their last clutch of eggs. This not only stops the female from producing more eggs, but also serves as another pair strengthening experience.

In order to successfully incubate all of the Whooping Crane eggs collected through multiple clutching, pairs of other crane species are used as surrogate incubators, including Siberian, Red-crowned, White-naped, and Sandhill Cranes. These other species gladly accept the eggs and are generally more effective at incubating the eggs than machine incubators.

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A Whooping Crane carefully tends to its nest at ICF.

Hatching and Rearing

When an egg is close to hatching (incubation length for Whooping Crane eggs is 29 days), it is placed in an incubator so staff can closely monitor the hatching process, which takes approximately three days. The first step is for the chick to internally pip, or break through the egg’s air cell located at the large end of the egg. At this point, the chick can be heard peeping from inside the egg. Next, the chick has to externally pip by breaking through the egg shell (top right). The third step is for the chick to rotate around the large end of the egg, continuing to break open the egg shell and finally push its way out (right).

Most Whooping Crane chicks hatched at ICF will be released into the wild. Chicks that are genetically valuable may remain in captivity and become part of the captive breeding population. Captive breeding of Whooping Cranes is currently underway at ICF, the U.S. Geological Survey’s Patuxent Wildlife Research Center in Laurel, Maryland; Audubon Species Survival Center in New Orleans; and the Calgary and San Antonio zoos.

chick_rearingChicks raised in captivity may be reared by adult Whooping Cranes or by staff, who wear full-length crane costumes to hide the human form while working with the young cranes (left, a costumed biologist exercises a chick in a pool). We use this costume-rearing technique to make sure the chicks imprint on Whooping Cranes (the costume and hand puppet mimic the colors and shape of an adult crane) and are prepared for life in the wild.

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Hatching step two - a Whooping Crane chick pips through the egg shell.

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Step three - the chick pushes its way out of the shell. 
Images © Joel Sartore/ www.joelsartore.com