Project Design

Direct Autumn Release: a different technique for reintroducing young cranes

What is a "direct autumn release"?

Direct autumn release is a reintroduction technique that is used in addition to the primary ultralight aircraft-led technique. The direct autumn release technique that will be used in the eastern migratory whooping crane reintroduction will consist of rearing whooping crane chicks according to a strict costume/isolation-rearing protocol and then releasing them with older whooping cranes that have successfully migrated in the past or into wild sandhill flocks with which these older whooping cranes are likely to associate. Chicks for direct autumn release will be reared from an early age in the field and then released after fledging. These released juveniles will then learn a fall migration route from the older, wild birds. This method of reintroduction has been extensively tested and proven previously successful with sandhill cranes.

Why do a direct autumn release of whooping cranes?

The direct autumn release of whooping crane chicks is an experiment to complement the known success of the ultralight-led migrations conducted by the Whooping Crane Eastern Partnership (WCEP). This initial success has so far placed more than 30 migrating whooping cranes back into eastern North America. Project managers feel there are enough birds in the wild to make direct autumn release a viable tool. Once a founder group has been established the direct autumn release can be used in conjunction with the ultralight technique to augment these numbers. This technique also affords several key benefits: (1) pending availability of eggs, a larger number of whooping cranes can be reintroduced into the migratory pathway each year, and (2) this technique could be used to continue adding birds to the population if the ultralight-led portion of the project ever became unavailable. In addition, the few chicks originally designated for ultralight-led migration but later found unsuitable could be salvaged by releasing them in the fall according to similar methods used in the direct autumn release. Otherwise, these latter birds might be placed into captivity and lost from the population. One such bird has already been salvaged in 2004 by releasing him with wild cranes, and he has subsequently migrated successfully.

How will you obtain the eggs for the direct autumn release?

Eggs will be collected from project partners and captive breeding facilities such as the USGS Patuxent Wildlife Research Center in Maryland. Chicks for the direct autumn release will then be hatched and isolation-reared until about three weeks of age at the International Crane Foundation's new chick-rearing facility in Baraboo, Wis. They will then be transferred to the isolation-rearing facility in the field at Necedah National Wildlife Refuge.

How will you select hatchlings for direct autumn release?

Earlier hatchings are preferred for the ultralight project, as these chicks are older and stronger prior to arrival at their fledging site in central Wisconsin, and they are better prepared to participate in the ultralight conditioning. Chicks hatched in June need not be as old or strong to start the conditioning process for direct autumn release. These later hatchlings would still have sufficient time to build up strength, fledge and be introduced to existing adults in the wild prior to the fall migration.

How will crane chicks be prepared for direct autumn release?

The chicks are raised according to isolation-rearing protocols including costumed handlers and no human voices. While at ICF, the chicks will be penned next to adult whooping cranes that act as live imprinting models. During their first summer at the Necedah NWR, the chicks live in specially-constructed facilities in the field, where they are likely to be visited by some of the older, wild cranes which will further facilitate proper imprinting. Each day the chicks will be led out of the pen by a costumed handler for exercise and exploration of refuge habitats, and when they are old enough they will be allowed to roam freely at a specific site within the refuge, but always under the watchful eye and supervision of costumed handlers.

How long will it take these birds to migrate to Florida?

Wild whooping cranes are soaring birds and use raising columns of warm air, or thermals, to carry them to altitude. Then they simply glide to the next thermal. By this method they can fly all day, expending minimal energy, and can complete the migration in as little as five to ten days.

How many birds will be released next year and in future years?

The direct autumn release depends on the availability of eggs. The overall goal of the migratory reintroduction project is to establish a self-sustaining flock of at least 125 migratory whooping cranes, including 25 breeding pairs, in eastern North America. To accomplish this, every effort is being made to make available viable chicks for both direct autumn release and ultralight-led reintroduction. If adequate eggs are produced in captivity, beginning in 2005, up to five chicks may be reared for the initial trial of the direct autumn release method. In future years, if the initial efforts are successful, the Whooping Crane Recovery Team will appropriate eggs on a yearly basis according to the success and availability of captive reproduction efforts.

How long will the direct autumn release technique be used?

As long as the technique proves viable and new chicks are available, the direct autumn release will be used in conjunction with the ultralight-led reintroduction into the foreseeable future or until the project's goal of a self-sustaining flock of 125 migratory whooping cranes is achieved.

Why do an ultralight-led release if we can do direct autumn releases that are more natural for the birds and less costly and time-consuming for people?

Initially the ultralight migrations were needed to establish a foundation population of whooping cranes and ensure that those cranes knew the migration route from Wisconsin to Florida. Now that a population of more than 30 migratory whooping cranes has been established, project managers can attempt direct autumn release where chicks can follow older cranes that know the direct autumn release technique may be less costly, the overwhelming success of the ultralight-led reintroduction technique has led project managers to conclude they will continue the technique along with direct autumn release into the foreseeable future. Additionally, more than one reintroduction technique may give the growing population of whooping cranes the best chance to succeed. It is hoped that some of the original founder birds will begin to breed in the near future and teach their offspring this migration route.

Why did we choose this bird to be released with older cranes?

It was initially hoped that number 18-04 would sufficiently integrate with the 2004 ultralight-conditioned flock. The chick was very young compared to other birds and was often distracted during conditioning. Additionally, the bird lost several of his primary flight feathers due to a medical condition, which further impeded his progress with ultralight conditioning. ICF's veterinarian found that the juvenile crane's lost primary feathers were growing back and that the bird's overall health was good. However, much of this improvement occurred late in the ultralight conditioning cycle. After careful consideration by the ultralight migration crew and discussion with project managers, a decision was made that 18-04 would be unsuitable for the ultralight-led migration but might be a candidate to release with older whooping cranes that were freely migrating. The successful release of no. 18-04 to salvage him as a member of the population will provide insight into the future direct autumn release.

What is the ESA status of birds that are direct autumn-released?

Like the ultralight-led whooping cranes, these cranes are designated as endangered species that are part of an experimental, nonessential population; meaning that they are isolated from other whooping crane populations and the survival of the species is not dependent on these individuals. These designations relax some of the restrictions of the Endangered Species Act and lessen possible conflicts between people and whooping crane conservation. All whooping cranes are still fully covered under the Migratory Bird Treaty Act.

Would you ever retrieve a direct autumn-released bird from the wild, and why?

Once released, the young cranes will be left in the wild to form associations with wild whooping cranes. However, if a juvenile bird's survival is threatened by unsafe roosting behavior, unsatisfactory habitat use, or inadequate avoidance of human contact, it will be recaptured. Additionally, if a direct autumn-released crane does not associate with older cranes, it may be retrieved from the wild and re-released at a later date to ensure the juvenile bird learns the appropriate migratory patterns and behavior.

How will the direct autumn-released birds be tracked in the wild?

These birds will be tracked during their first autumn migration and thereafter by U.S. Fish and Wildlife Service and International Crane Foundation staff using VHF and satellite telemetry. Wisconsin Department of Natural Resources biologists assist with monitoring the birds while they are at their summer locations.

What does success look like in terms of the direct autumn release portion of the project?

As with the ultralight-led cranes, the goal of WCEP is for the majority of the direct autumn released birds to complete a fall migration and then return to Necedah NWR the following spring. Additionally, it is important that the juvenile whooping cranes find suitable habitat in the summer after they are first released, as well as during their fall and spring migrations and on their wintering grounds.

If I see a whooper on my property, on my neighbor's property, or at the park, what should I do?

The most important thing to remember is, do not approach the bird. Each exposure lessens the birds' natural fear of humans, which is an important survival mechanism. You should contact your local Department of Natural Resources to report your sighting and they will advise you accordingly. As a result of the relaxation of protections associated with this rule, no conflicts are envisioned between the whooping cranes' reintroduction and activities on private lands. Any disturbance of nesting cranes on private property that is accidental or incidental to an otherwise lawful activity, such as recreation (hunting, trapping); agricultural practices (plowing, planting, application of pesticides, etc.); or construction or water management would not be considered an illegal activity under the Endangered Species Act.