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<br />1990,12 eggs were transferred from WBNP to ICF, 11 were fertile and 8 fledged. Nine
<br />eggs were laid by three captive females in 1991, and one chick was parent-reared (Table 6),
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<br />In 1992, the same three breeding pairs produced 16 eggs (3 from natural copulation), and 6
<br />were reared. Closed circuit TV proved effective in (a) eliminating egg breaking by a pair that
<br />broke eggs in 1991, and (b) in monitoring and supervising the socialization of new pairs.
<br />Eleven eggs were received from WBNP, and 7 chicks fledged, One captive-produced chick
<br />was parent-reared, 4 were hand-reared, and one (together with 7 chicks from AWP eggs)
<br />was costume-reared, Costume-rearing refers to the use of a white crane-like costume worn
<br />by animal caretakers whenever they are around the: birds. In this manner, cranes are never
<br />exposed to the human form and remain fearful of Plilople. From the time of hatching,
<br />costume-reared whoopers are exposed to live whodping crane role models in adjacent pens
<br />I
<br />to avoid imprinting problems. Eight of the costume+reared birds were sent to Florida in
<br />January 1993 for the reintroduction experiment. In 1993, three females produced 9 eggs
<br />and four chicks fledged. ICF also received nine fertile eggs from WBNP, eight hatched and
<br />all fledged. Four were sent as chicks to Idaho for use in the guide bird research. In August
<br />1993, ICF held three breeding pairs, three mature females being re-paired to stimulate
<br />breeding, five other pairs nearing sexual maturity, a: single adult male, four yearlings, and
<br />eight juveniles. ICF has the capacity to house 16 breeding pairs of whooping cranes.
<br />Research is ongoing to improve reproduction, rearing procedures, behavioral management,
<br />health care, and other topics which may directly benefit management and recovery,
<br />
<br />J. The Cross-Fostering Experiment
<br />
<br />For any species, the probability of extinction is largely determined by its abundance,
<br />fecundity, and distribution, . Conventional management procedures for the whooping crane
<br />have been aimed primarily at increasing the size of the AWP population. Even though this
<br />population has increased substantially since the 1940's, it remains vulnerable due to its
<br />relatively restricted breeding and wintering distributions. It was recognized that survival
<br />prospects for the whooping crane would be greatly enhanced by establishing additional,
<br />disjunct populations. Although several approachesto establishing additionel breeding
<br />populations had been proposed, the technique which seemed most worthy of consideration
<br />was cross-fostering whooping cranes to sandhill crane foster parents. This procedure was
<br />initially proposed in the 1960's by Fred Bard, a former Director of the Saskatchewan
<br />Museum.of Natural History. By this method, whooping crane eggs from the wild or from
<br />captive breeders would be placed in sandhill crane nests, and the sandhill cranes would
<br />incubate, hatch, rear, and introduce the whooping qrane chicks into the wild.
<br />
<br />Cross-fostering is relatively simple and could be applied in various areas formerly within the
<br />whooping cranes breeding range. Furthermore, migration routes, stopover points, and
<br />wintering locations could ba determined in advance by banding and subsequently observing
<br />potential foster-parent pairs, Despite these obvious advantages, the technique raised a
<br />number of unanswered questions: Would the food items used by sandhill cranes be
<br />nutritionally adequate for whooping cranes? Would!altitudinal differences between the
<br />source of the eggs and the transport point affect h~tchability? Would whooping crane
<br />chicks become sexually imprinted upon sandhill cranes, and eventually select e sandhill
<br />mate? These and other questions could only be anSwered by experimentation (Drewien and
<br />Bizeau 1978, Drewien and Kuyt 1979),
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