WSP05055

• File Number: 8460.500
• Description: Platte River Recovery Plan
• Basin: South Platte
• Date: 2/11/1994
• Author: USFWS
• Title: Whooping Crane Recovery Plan
• Water Supply Pro - Doc Type: Publication

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a Two of 14 eggs lost to predators,
b Four of 15 eggs lost to predators.
c Three eggs deserted after a snowstorm, one egg lost to a predator..
d Examination of 10 eggs that did not hatch revealed that 4 were infertile, 2 contained
early-dead embryos, and 4 contained late-dead embryos,
e Poor hatchability of PWRC eggS-during the period 1976-1978 was due largely to egg
infertility (11 eggs) and artificial incubation (20 eggs), After 1978, only eggs containing
viable embryos (as determined by flotation) were t~ansferred and all eggs were incubated
under sandhill cranes at PWRC before their transfer.
f One egg lost to a predator before hatching.
9 Three eggs lost to predators before hatching.
h Three eggs believed to be infertile or to contain early dead embryos at the time of
transfer.
i Two eggs were eaten by predators and two failed to hatch.

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The new pair remained together for over four months, Between 5 - 1 5 October, the male
was observed initiating migratory flights on five occasions with the female following,
However, the female was unable to keep up with the male and she always returned to the
territory with the male following, On October 15 the male migrated alone, The only other
whooper present, a wild male, immediately joined the female for 2 days until he migrated,

The female's history of six years in captivity appar~ntly rendered her phYSically incapable of
sustaining long flights, Attempts to capture her in late October were unsuccessful and she
disappeared, The behavior of the males at GL demonstrated that they were highly
responsive to the presence of a female during the ~reeding season, Observations indicated
that a long-term pair bond would probably have ocdurred had the female been able to fly
properly and completed the migration. '

During the 1980's it became apparent that older females did not return to GL or other areas
occupied by territorial males during the summer, Experiments to enhance pair formation
were carried out from 1986 through 1990 whereby: 20 whooping cranes (some individuals
were recaptured several times>' were captured in isolated summer sites and released at GL
near male whooping cranes (Drewien and Clegg 19~2). Five (2 males, 3 females) were held
for one to four months in a pen prior to being released. Objectives of the experiment was to
,
enhance pair formation opportunities, Although the;se translocation experiments contributed
to numerous associations and interactions between,;ndividuals of both sexes, no permanent
pair bonds developed. The longest associations lasted two to four months before males and
females separated. These results suggested that imprinting problems possibly existed in
. whooping cranes raised by sandhill cranes. The females exhibited only minimal responses
to the presence of males,

From 1975 through 1988,289 eggs were transferrEld (including 73 eggs from the captive
flock at the PWRC), 210 hatched, and 85 chicks fledged (Drewien et al. 1989, Elliset ai,
1992), The RMP peaked at 33 birds in 1985 and has declined since then to 10 birds, Dr.
Edward 0, Garton, biometrician at the University of Idaho, working with Dr. Rod Drewien
the leader of the cross-fostering project (Garton et ai, 1989), modelled the cross-fostered
population to predict when it might become self-sustaining. In the model they assumed (1)