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fl uctuati ons in water level s, seasonal avail ability of intermittent or <br />ephemeral wetl ands, and changing water- and 1 and -use appl icati ons) . Such <br />habitat changes do not pose jeopardy to the species as long as other suitable <br />stopover options are adequately distributed and available throughout the <br />flyway. <br />WHOOPING CRANE USE OF THE PLATTE RIVER <br />Historical Record (Section 3.1) : The Service's original proposed determination <br />of the Platte River critical habitat zone on December 16, 1975 was based on the <br />premise that this river and its environs constituted the "most valuable part" <br />of the whooping cranes entire migration route. The rationale was that 1) there <br />were more old records of whooping crane sightings along the 'Big Bend" area of <br />the Platte River than anywhere else along the flyway; and 2) confirmed <br />sightings during the few years preceedi ng the proposed determination indicated <br />continued heavy use of the area. <br />The preponderance of early records along the Platte River was due to the <br />efforts of Myron H. Swenk, a professor at the University of Nebraska, and A. M. <br />Brooking of the Hastings Museum, who actively solicited and compiled reports of <br />whooping crane sightings in Nebraska from 1912-1933, and from 1934 -1944, <br />respectively. Swenk and Brooking relied on the observations of others (e. g. , <br />farmers, ranchers, local residents and hunters, most of wham lived in the 'Big <br />Bend" area) and did not field-verify the sightings. The interest generated by <br />these researchers at a time when knowledge of the whooping crane's migratory <br />habits was fragmentary--and when similar observation efforts were not being <br />coordinated at other locations al ong the flyway- -thus resulted in a dispropor- <br />tionate number of sightings along the Matte River prior to 1950. <br />While conducting research on the species during the 19401s, Robert Porter Allen <br />of the National Audubon Society thoroughly reevaluated the sightings records <br />compiled by Swenk and Brooking. In the process, Allen discovered a substantial <br />disparity between the large numbers of migrant whooping cranes reported in <br />Nebraska and the species' status at wintering grounds in Texas and Louisiana <br />where it had become rare after 1912. In some cases, he noted that individual <br />flocks sighted in Nebraska exceeded the species' total population size as <br />determined fran counts on the winter grounds. <br />Allen attributed this disparity in numbers to "honest mistakes in identifica- <br />ti on ". on the part of the Nebraska observers, an explanation that he further <br />supported through personal follow -up of sightings reported to him. A <br />significant consequence of this problem was that the Nebraska records falsely <br />reflected an increase in the whooping crane popul ati on -- interpreted by Swenk as <br />a "distinct recovery of the species"--during a period when the population was <br />experiencing serious decline. The encouraging picture presented by the <br />Nebraska records unfortunately delayed needed recovery action. <br />In his classic monograph on the species ( "The Whooping Crane ", published in <br />1952), Allen eliminated records involving at least 77 percent of the whooping <br />cranes sighted in Nebraska from 1912 -1944, including approximately 68 percent <br />of the birds reported by Swenk (1912 - 1933), and approximately 92 percent of the <br />IV <br />