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41 <br />The cross - fostered females would be breeding at the same rate as the females in Canada; <br />and (2) survival of birds in their first year would be similar to that of first year birds in <br />Canada (Garton at al. 1989). Despite these optimistic and unrealized assumptions, with the <br />future transfer of 30 eggs per year, the population would only reach 6 breeding pairs after <br />50 years. "it is obvious from all scenarios modelled that egg transplants of less than 30 <br />eggs per year will not suffice to establish a self - sustaining population in a reasonable period <br />of time. Natural breeding will be essential to establish a self- sustaining population" (Garton <br />at al. 1989). The lack of pairing and reproduction, prolonged drought on the summer area, <br />and the high mortality led to discontinuing the egg transfers in 1989. <br />Sexual imprinting of a foster - reared species on the foster - parent species had already been <br />confirmed in foster - reared raptors, waterfowl, gulls, finches, and gallinaceous birds (Bird at <br />al. 1985, Immelmann 1972). One test of the imprinting problem occurred at ICF where <br />sandhill cranes were foster - reared by red- crowned cranes (sample of one), white -naped <br />cranes (sample of 2), and Siberian cranes (sample of one). When given a choice the cross - <br />fostered sandhill cranes socialized more with the foster species than with conspecifics. The <br />two foster - reared females showed a stronger preference for the foster species than did the <br />two foster- reared males (Mahan and Simmers 1992). By the fall of 1992, cross- fostered <br />adult female whooping cranes of ages 4 through 12 years had passed through a nesting <br />season on 34 occasions without pairing. Whooping cranes at WBNP begin egg production <br />at an average age of 4 years (E. Kuyt, pers. comm., 1991). <br />In 1992, a wild cross - fostered male whooping crane paired with a female sandhill crane to <br />produce a hybrid chick. Four hybrids were previously produced by artificial insemination in <br />captivity at Patuxent. The hybrid wild chick provided additional evidence that <br />cross- fostering may break down behavioral barriers that normally discourage pairing <br />between the two species. <br />K. Reintroduction Studies In The East <br />A November 21, 1975, letter to members of the Whooping Crane Recovery Team from the <br />Florida Game and Fresh Water Fish Commission (Commission), suggested the possibility of <br />reestablishing a non - migratory whooping crane population in the eastern United States. No <br />genetically pure representative of the nonmigratory Louisiana flock remained in captivity. <br />The letter proposed that Florida sandhill cranes might be used as surrogate parents to instill <br />non - migratory behavior into cross - foster whooping cranes with the goal of restoring a <br />non - migratory flock in the Southeast. It should first be determined that migratory sandhill <br />cranes reared by Florida sandhill crane foster parents would be non- migratory. <br />In 1977, John Allender (Audubon Park Zoological Garden) and George Archibald submitted a <br />proposal to reintroduce whooping cranes to Louisiana. The proposal was tabled for several <br />reasons. The Service did not wish to endorse other reintroduction efforts until the cross - <br />fostering project was fully evaluated (letter of Lynn Greenwalt, Director, FWS to Regional <br />Directors, May 1978). Wildlife agency personnel were also concerned that critical habitat <br />might be designated within the State as a consequence of a release, a designation which <br />might lead to unfavorable constraints on land and hunting management (March 1978 letter <br />of J. Burton Angelis, Secretary, Louisiana Wild Life and Fisheries Commission, to George <br />Archibald). Resource agency personnel in Louisiana were concerned that restrictions on <br />