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40 <br />a Two of 14 eggs lost to predators. <br />b Four of 15 eggs lost to predators. <br />c Three eggs deserted after a snowstorm, one egg lost to a predator: <br />d Examination of 10 eggs that did not hatch revealed that 4 were infertile, 2 contained <br />early -dead embryos, and 4 contained late -dead embryos. <br />e Poor hatchability of PWRC eggs - during the period 1976 -1978 was due largely to egg <br />infertility (1 1 eggs) and artificial incubation (20 eggs). After 1978, only eggs containing <br />viable embryos (as determined by flotation) were transferred and all eggs were incubated <br />under sandhill cranes at PWRC before their transfer. <br />f One egg lost to a predator before hatching. <br />g Three eggs lost to predators before hatching. <br />h Three eggs believed to be infertile or to contain early dead embryos at the time of <br />transfer. <br />i Two eggs were eaten by predators and two failed to hatch. <br />The new pair remained together for over four months. Between 5 - 15 October, the male <br />was observed initiating migratory flights on five occasions with the female following. <br />However, the female was unable to keep up with the male and she always returned to the <br />territory with the male following. On October 15 the male migrated alone. The only other <br />whooper present, a wild male, immediately joined the female for 2 days until he migrated. <br />The female's history of six years in captivity apparently rendered her physically incapable of <br />sustaining long flights. Attempts to capture her in late October were unsuccessful and she <br />disappeared. The behavior of the males at GL demonstrated that they were highly <br />responsive to the presence of a female during the breeding season. Observations indicated <br />that a long -term pair bond would probably have occurred had the female been able to fly <br />properly and completed the migration. <br />During the 1980's it became apparent that older females did not return to GL or other areas <br />occupied by territorial males during the summer. Experiments to enhance pair formation <br />were carried out from 1986 through 1990 whereby 20 whooping cranes (some individuals <br />were recaptured several times) were captured in isolated summer sites and released at GL <br />near male whooping cranes (Drewien and Clegg 1992). Five (2 males, 3 females) were held <br />for one to four months in a pen prior to being released. Objectives of the experiment was to <br />enhance pair formation opportunities. Although these translocation experiments contributed <br />to numerous associations and interactions between individuals of both sexes, no permanent <br />pair bonds developed. The longest associations lasted two to four months before males and <br />females separated. These results suggested that imprinting problems possibly existed in <br />whooping cranes raised by sandhill cranes. The females exhibited only minimal responses <br />to the presence of males. <br />From 1975 through 1988, 289 eggs were transferred (including 73 eggs from the captive <br />flock at the PWRC), 210 hatched, and 85 chicks fledged (Drewien et al. 1989, Ellis at al. <br />1992). The RMP peaked at 33 birds in 1985 and has declined since then to 10 birds. Dr. <br />Edward O. Garton, biometrician at the University of Idaho, working with Dr. Rod Drewien <br />the leader of the cross - fostering project (Garton et al. 1989), modelled the cross - fostered <br />population to predict when it might become self- sustaining. In the model they assumed (1) <br />