A REINTRODUCTION EXPERIMENT INVOLVING MATED PAIRS OF PARENT-REARED GREATER SANDHILL CRANES IN NORTHERN ARIZONA

In April 1997, 4 mated pairs of adult greater sandhill cranes (Grus canadensis tabida) were abrupt-released at Monnon Lake, Arizona. Five of 8 adult cranes died within 10 days of release. One crane flew from the release area within 10 days after release and was never relocated. One pair of cranes, with 1 pair member sustaining a broken wing 4 days after release, survived for 4 months and demonstrated the importance of maintaining pair bonds after release. The cause of death of at least 5 birds was predation. The high immediate mortality and complete long-term mortality experienced in this pilot project suggests that adult cranes are poor candidates for release. These poor results encourage that, in future release attempts with mated pairs or other adult cranes, it is important to provide the cranes with roosting habitat while still in captivity and to hold the cranes in an acclimation pen at the release site for several days prior to release

A COMPARISON OF BEHAVIOR FOR TWO COHORTS OF CAPTIVE-REARED GREATER SANDHILL CRANES RELEASED IN NORTHERN ARIZONA

To determine how the behavior of greater sandhill cranes (Grus canadensis tabida) changes according to time of year, time of day, and number of days after release, we observed the activities of 2 groups of captive-reared greater sandhill cranes at Mormon Lake, northern Arizona. The behaviors we compared were alert, loafing, sleeping, foraging, preening, locomotion, and other. We found costume-reared subadult greater sandhill cranes that were established at the study site for a year spent more time foraging and being alert towards predators than parent -reared juvenile greater sandhill cranes that were recently released from captivity. We also found that with time juvenile sandhill cranes were increasingly alert and spent less time loafing. It appeared that captive-reared juvenile sandhill cranes learn behavior important for survival from previously released captive-reared cranes

FATE OF THE SURVIVORS OF THE 1995 AND 1996 ARIZONA TRUCKING MIGRATIONS OF COSTUME-REARED GREATER SANDHILL CRANES

In 1995 and 1996, we trained 2 groups of costume-reared greater sandhill cranes (Grus canadensis tabida) (10 in 1995, 14 in 1996) to follow a truck. Thereafter we led 10 in 1995 and 12 in 1996 from Garland Prairie, northern Arizona, to the Buenos Aires National Wildlife Refuge, southern Arizona (ca. 620 km). These techniques were being developed to create additional, disjunct populations of the whooping crane (G. americana). The cranes taught the migration route in 1995 did not follow the desired migration route in 1996 but did travel north 140 km along the route in spring 1997. By the summer of 1997, we did not know the locations of any of these birds. Results were better for the 1996 trucking cranes. Between 1997 and 1999 there was a 92% (11 of 12) success rate for the 1996 trucking cranes with known locations flying unassisted from the summering to wintering grounds. Through 1999, 7 of the 12 cranes became lost on flights from the wintering to summering grounds. (Some of the trucking cranes apparently followed wild cranes to or toward breeding grounds.

THE ONE-8Y-ONE METHOD FOR RELEASING CRANES

Although the trend for the past 2 decades has been toward releasing naive groups of juveniles after a lengthy acclimation period, in 5 separate releases (1996-2000) we tested the idea that naive juvenile greater sandhill cranes (Grus canadensis tabida) would survive better if released singly into a wild flock of predator-wary birds than if left as a group, inexperienced at foraging and ill prepared to avoiding predators. We released 3 groups of hand-reared juveniles (n = 12 [1996]; n = 8 [1998], n = 12 [1999]) into a wild flock of sandhill cranes (ca 300 birds) on wintering grounds near Gila Bend, Arizona. Another 8 parent-reared colts were released into a small group (4) of sub adult greater sandhill cranes (survivors of the 1996 trucking experiment [Ellis, et aI. 1997; Ellis et al. 2001, Mummert et aI. 2001]) in northcentral Arizona. Another 8 juveniles, costume-reared from hatching, were released into wild sandhill crane flocks in central Wisconsin at autumn staging areas. In all of these tests, cranes were released 1 or 2 at a time, either at the periphery of a wild flock or at a known roost site. Most birds were released in daylight at a foraging area, but because this was a pilot project, we tried a variety of methods. We released a few individuals at odd times (e.g., midnight) and in odd ways (e.g., by flushing a release crane as a wild flock passed overhead). A few birds were initially left stranded after we placed them at ephemeral roosts that had been used recently, but not subsequent to our visit. However, once we made the necessary adjustments, and regardless of release time or situation, all of our cranes very quickly joined their adoptive flocks. We experienced excellent survival, including 100% survival for all 8 of our parentreared fledgling colts released on the sununering ground and followed until they disappeared at the time of migration. Further, all (32) hand-reared birds released on the wintering grounds survived the winter. Also all 8 of the juveniles reared and released in Wisconsin successfully migrated south and returned north to Central Wisconsin the following spring. These results recommend the one-by-one method as a promising strategy for releasing juvenile cranes with minimal training, handling, and maintenance. The method provides a likely strategy for building wild flocks of endangered cranes once a core group is established by some other method

RESULTS OF THE SECOND (1996) EXPERIMENT TO LEAD CRANES ON MIGRATION BEHIND A MOTORIZED GROUND VEHICLE

Fourteen greater sandhill cranes (Grus canadensis tabida) were trained to follow a specially-equipped truck and 12 were led along a ca 620-Ian route from Camp Navajo in northern Arizona to the Buenos Aires National Wildlife Refuge near the ArizonalMexico border. Ten survived the trek, 380 Ian of which were flown, although only a few cranes flew every stage of the route. Major problems during the migration were powerline collisions (ca 15, 2 fatal) and overheating (when air temperatures exceeded ca 25° C). The tenacity of the cranes in following both in 1995 and 1996 under unfavorable conditions (e.g., poor light, exireme dust, or heat) demonstrated that cranes could be led over long distances by motorized vehicles on the ground