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WSP05055
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Last modified
1/26/2010 2:16:45 PM
Creation date
10/12/2006 12:48:38 AM
Metadata
Fields
Template:
Water Supply Protection
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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<br />~...~ <br /> <br />29 <br /> <br />abnormalities, and leg disorders resulting from rapid growth (Kepler 1978). Carpenter and <br />Derrickson (1981) summarized all mortalities in the captive flock from 1967 to 1981. <br /> <br />Eggs were first produced at PWRC in 1975, when one female laid three eggs (Table 3). <br />Although two females produced eggs when they were 5 years old, most captive females <br />have not laid until they were 7-11 years old (Table 4). Factors identified as responsible for <br />delaying reproduction in the captive flock include rearing conditions, dominance <br />relationships, age oJ separation of potential pairs from bachelor flock, sexual compatibility, <br />inadequate pen size, and stress associated with handling and disturbance (Kepler 1976, <br />1978, Derrickson and Carpenter 1981). <br /> <br />Between 1975 and 1993, the captive flock at PWRC produced 356 eggs (Table 3), <br />Seventy-three whooping crane eggs were transferred from PWRC to Grays Lake between <br />1976 and 1984, To date, annual production has been primarily limited by the number of <br />breeding pairs, and egg fertility. Although productive pairs at PWRC exhibit copulatory <br />behavior, and males regularly attempt to mount their mates, successful natural copulations <br />were not observed until 1991. In the spring of 1991, a pair of full-winged, behavioral <br />conditioned, captive-reared whooping cranes, laid the first fertile egg at PWRC without <br />artificial insemination. The Service believes naturally fertile pairs will lay more eggs than <br />artificially inseminated birds. Natural fertilization reduces the risk of injury due to handling. <br />To avoid imprinting problems, PWRC now rears chicks outdoors with a pair of whooping <br />cranes or hand-rears them in visual and auditory contact with a subadult whooping crane <br />role model. In 1992, five additional pairs produced five chicks by natural breeding. To <br />acquire fertile eggs from badly imprinted or handicapped individuals, the females have been <br />artificially inseminated using a variation of the massage technique (Gee and Temple 1978). <br />In order to condition pairs to this procedure, the collection of semen from males and the <br />handling of females are initiated well in advance of laying. Females are inseminated from <br />the time their pubic bones begin to separate until laying ceases. Throughout this period, <br />females are routinely inseminated three times per week and after each oviposition. <br /> <br />From 1975 through 1981,55 of 61 eggs (90 percent) were fertile, from 1982 through <br />1986,89 of 97 eggs (92 percent), and from 1987 through 1992,41 of 53 eggs (77 <br />percent) were fertile from whooping cranes artificially inseminated. Fertility of artificially <br />inseminated eggs over the entire period through 1992 averaged 86 percent. Between 1987 <br />and 1992, the PWRC flock produced 74 eggs (50 fertile). From these 50 and 43 other <br />fertile eggs obtained from WBNP, PWRC fledged 49 birds. During the same interval, PWRC <br />shipped 22 birds to ICF in 1989 to help establish a second captive flock and 6 birds to <br />Florida for release in 1993. The flock was split to reduce the risk of disease outbreaks <br />decimating the entire captive population, <br /> <br />Early attempts to artificially incubate whooping crane eggs suggested problems with less <br />than optimum incubation regimes. Results obtained in 1978 supported this conclusion, <br />because (1) hatchability of the 8 eggs retained at PWRC and incubated under sandhill cranes <br />was 88 percent, (2) of 11 fertile eggs which were incubated artificially before their transfer <br />to GL, only 5 hatched; and (3) the 6 fertile eggs that did not hatch at GL contained 4 late <br />dead, and 2 early dead embryos, Hatchability of whooping crane eggs incubated by cranes <br />exceeds that of eggs incubated in incubators. As a result, since 1979 all whooping crane <br />
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