Scott Hereford, Gautier, MS (scott_hereford@fws.gov)

For the captive flocks of endangered North American cranes this has been a good year but not an exceptional year. There were a large number of eggs laid by the captive whooping cranes. The production of the Mississippi sandhill cranes had to be curtailed because of the problems last winter with finding a positive culture for avian tuberculosis in one crane scheduled for release. Here is a summary of crane production by facility:

At the Calgary Zoo’s breeding facility in Alberta, six pairs had eggs, including four new pairs. A total of 28 eggs were laid. Five of these were fertile and hatched. All five hatched, but unfortunately, one chick broke its leg. Surgery was performed to repair the fracture, but the chick died in post operative recovery. Of the current four whooping cranes, three are being costumed reared and one is being parent reared. In addition, two Florida sandhill crane chicks are being costumed reared, and two more will be hatched and raised by whooping crane pairs to give them chick rearing experience.

At the San Antonio Zoo in Texas one whooping crane chick is being costume reared. They had eight eggs laid from two pairs, but only one egg was fertile. In addition to the two pairs, they have two juvenile whooping cranes that hatched last year.

At the International Crane Foundation in Baraboo, Wisconsin, five whooping crane females produced 21 eggs, of which six were fertile. Four eggs hatched with one chick being parent reared and three costume reared. One chick had to be euthanized at 18 days due to developmental problems.

Patuxent Wildlife Research Center, Laurel, Maryland, had ten pairs laying a total of 52 eggs. Of these, 31 were fertile and 29 hatched. Of the ten females that laid eggs, two laid for the first time. From the 29 chicks that hatched, 11 were assigned to the Whooping Crane Eastern Partnership project, 17 to the Florida non-migratory release effort and 1 to captivity for genetic reasons. Patuxent has had three chicks die, one from peritonitis, one from drowning, and one currently listed as unknown but awaiting test results. This leaves 10 for the Whooping Crane Eastern Partnership, 15 for the Florida release and 1 for captivity.

For the Mississippi sandhill cranes, the majority of the production has been at White Oak Plantation in Yulee, Florida. Of the first clutches laid, there were ten eggs, seven of which were fertile. All these eggs were sent to ACRES/Audubon Zoo in New Orleans, Louisiana where all seven hatched. Five are being costume reared and two are being parent reared. On the second clutches, again ten eggs were laid. Four were infertile, two died in the shell before hatching and four hatched. Of these four, two died within two days of hatching, and the other two are doing well.

At the ACRES/Audubon Zoo, in addition to the seven chicks from White Oak, they had two naturally fertile pairs that laid three eggs total. All three eggs hatched, with two being costume reared and one parent reared. Audubon was holding 15 Mississippi sandhill cranes from hatch year 2000 due to the positive test for avian tuberculosis that occurred last winter. Subsequent testing has all been negative, so this spring eight of the cranes were release on the Refuge in Ocean Springs, Mississippi, while seven more cranes are awaiting release in the Fall of 2001. But because of these additional cranes, the decision was made not to use artificial insemination on the pairs of Mississippi sandhill cranes at Audubon to increase the number of chicks being raised this year. Audubon also has four whooping cranes and the one pair there did show signs of nest building this spring, but laid no eggs.

I wish to thank Mary Ann Wellington at the International Crane Foundation, Mike Taylor at White Oak Plantation, Allan Shoults at the Calgary Zoo, Megan Lauber at the Audubon Zoo, Josef San Miguel at the San Antonio Zoo, and Jane Nicolich at Patuxent Wildlife Research Center for the information used to compile this report.

In 2000, a diverse group of folks teamed together to conduct an experiment leading sandhill cranes along a migration route with ultralight aircraft. The goal of the project was to refine a technique that could be used in the future for reintroducing a migratory flock of whooping cranes to eastern North America. Biologists reared and trained birds at Patuxent Wildlife Research Center in Laurel, Maryland, then transferred them to Necedah NWR, Wisconsin at about 5 weeks of age. In the fall, after flight training at Necedah, the ultralights led the cranes on migration to Chassahowitzka NWR in Florida. The birds overwintered at the refuge in Florida and in the spring migrated back to Wisconsin on their own.

Many measures can be used to quantify the successes of last year’s study. We were able to identify a route through the heart of America that kept us clear of restricted airspace and yet closely aligned with the traditional migratory flyway. We found 35 stopovers that allowed us to lead birds from Wisconsin to Florida without exposure to people. We streamlined our training procedures and reduced human contact to the lowest level yet and provided the birds with a natural experience. We set the protocol for future studies while leading eleven birds over 1200 miles and into the imaginations of adventurers and naturalists around the world.

The Bird Team that was set up to carry out the reintroduction approved two studies last year. Both were designed to produce birds that would follow our aircraft but used different methods.

The primary study used an established technique originally developed by Operation Migration over many years with several species. It involved rearing the birds under the expert tutelage of the staff at Patuxent Wildlife Research Center in Maryland and conditioning them to the aircraft starting even before they hatched. We believe that by beginning early the birds can be encouraged to follow the ultralight with only minimal human contact. This reduced exposure to people allows them a more natural experience, free from human interaction. There is less chance that the birds will become overly attracted to handlers and they are more likely to correctly imprint on the adult cranes that were penned next them.

The alternate training method was tested to see if birds could be introduced to the aircraft after they were 30 to 40 days old to allow more flexibility in where the training could take place. These birds, known as cohort 3, were reared at Necedah NWR in Wisconsin, which avoided the necessity of shipping them to and from a captive breeding center. Although they were not introduced to adult birds of the same species, handlers led them through wetlands for several hours each day. At night they were housed in individual pens and they were allowed to socialize while supervised by handlers. This additional conditioning to the costumed parent resulted in a reluctance to follow the aircraft even after receiving more conditioning time than the primary study birds. They were so attracted to the handler that they would only respond if the one they were most familiar with operated the aircraft, despite all the crew being identically costumed. Damage to one of the aircraft curtailed the training schedule and when it was resumed several attempts were made to lead the birds in flight. Unfortunately they showed little interest and would not follow the aircraft on the ground or in the air. The two comparison studies proved that over conditioning birds to handlers is not conducive to encouraging them to follow aircraft. Eventually the training was discontinued and the birds were used to re-test a one by one release technique developed by Dr David Ellis of Patuxent WRC.

Early training of the primary study birds at Patuxent WRC involved the use of a circle pen, which was an enclosure 30 feet in diameter and 2 feet high. Mealworms were used as a treat to entice the chicks to follow from the inside while the aircraft taxied around the perimeter. This protected the birds from the propeller and reduced the number of people required to conduct the training. The birds were led by the aircraft most of the time to minimize their exposure to walking handlers. The training scheduled was dictated by performance; if the birds followed perfectly, further training sessions were postponed. We reasoned that reinforcing a lesson already learned was not worth the additional contact time. We also used adult cranes as role models and digitally recorded calls to ensure that the chicks were sexually imprinted on the correct species. All of these improvements on our earlier techniques allowed us to reduce the conditioning time so the birds were following us with much less human interaction. Before they were moved to Necedah NWR in Wisconsin they received only 7 hours of exposure to the aircraft.

Once at the introduction site in Wisconsin they were penned in enclosures that were disguised to look more natural. Earth tones were used and trees were planted to help mask the human appearance. After early morning training sessions the birds were allowed their freedom, giving them the opportunity to socialize and establish their natural dominance structure unsupervised. Prior to departure on migration, the birds worked with the aircraft for an additional 22 hours. By comparison, in 1997 it took us 287.5 hours to encourage the birds to follow us in flight. That time was reduced to 63 hours the next year and we now have it down to less than 30 hours giving the birds every opportunity to maintain their wildness.

During the 40-day migration we made 33 stops and covered 1227.5 miles. The birds flew a total of 29 hours and 51 minutes on the 31 days when the weather cooperated. Once in Florida the flock became sedentary, leaving the pen to forage in a pasture close by. On February 25 of this year they took off and circled the pen as they often did, only this time they disappeared over the northern horizon. On April 27th, 10 birds were confirmed back at Necedah National Wildlife Refuge in Wisconsin. The return of the Sandhill cranes from last year’s study is very encouraging. The accuracy of the return, the fact that they landed right at the training area, adds credibility to our technique, but what excites us most is their wildness. Managing their experiences and providing a natural environment for the seven months that they were in our care took its toll on the team. For 62 days these immature birds meandered north, covering 1250 miles without one report of human interaction. They avoided people and behaved like wild birds should, proving the worth of our efforts. Our hope was to have as little impact on them as possible, to avoid familiarity with humans, yet instil in them the memory of a summer home and the knowledge of how to return there. Their behaviour validates our methods and opens the door to Phase II of the program. A criterion for success was established by the Bird Team to judge the behaviour and survival rate of the birds once they were released. The goals were set high to justify using the technique with an endangered species but the primary study exceeded the parameters and prompted the Recovery Team to support the reintroduction pending Federal and State approval.

R. P. Urbanek, K. Brunette, M. Knoch, S. Swengel, M. Wellington, K. Maguire, S. Zimorski, T. Kaldenberg, L. Moore, M. McDaniel, and W. Hall

All experimental cranes integrated completely into wild flocks within a few days, and all survived to migrate from Central Wisconsin with wild flocks approximately13-18 November. Four males were recorded during fall migration at Jasper-Pulaski Fish and Wildlife Area, Indiana. Monitoring effort there was minimal, and no checks were made during the initial migration period. Six of the 8 cranes were confirmed wintering within large wild flocks on the following major sandhill crane wintering areas:

Grand Prairie, Okefenokee Swamp, Georgia (1 male)
Hixtown Swamp, Madison Co., Florida (1 female)
Ashley Prairie and Smith Lake, Putnam Co., Florida (1 male)
Fish Prairie, Marion Co.; and Paynes Prairie and Lake Kanapaha, Alachua Co.; Florida (1 male)
Hiwassee Refuge, Meigs Co., Tennessee (2 males)

One female and one male with malfunctioning transmitters were not found during the winter.

All 8 of the costume isolation-reared cranes returned to Central Wisconsin in spring 2001. Seven of them returned to and have remained in the primary study area (proposed whooping crane reintroduction area). Three of these birds were males who have settled in the immediate rearing area near Rynearson Pools on Necedah NWR even though two of these were released elsewhere. The remaining bird of the 8, the female with the nonfunctional transmitter, was observed several times earlier this spring at a large crane area 34 miles southeast of the rearing site.

These results are consistent with those of three cohorts of sandhill cranes reared and released at Seney NWR, Upper Michigan, in 1988, 1989, and 1990. In those releases, the majority of males returned and established residence on the immediate rearing/release area and then went on to successfully pair, establish territories, nest, and produce young. All of these birds were costume isolation-reared from hatching on the experimental reintroduction area and then released locally within wild sandhill flocks. This rearing and release procedure resulted in excellent release candidates who developed a strong philopatric association with their natal area. For a reintroduction of whooping cranes to be successful, it is critical that the initial core group of captive-reared birds return to and remain in the target reintroduction area the following spring/summer and subsequent breeding seasons. The research at Seney and Necedah indicates that this objective may be readily accomplished by proper rearing and release methods.