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Whooping Crane <br />Background <br />The whooping crane (Gnus americana) was listed as a federally endangered species on <br />March 11, 1967, and critical habitat was designated on May 15, 1978. Its principal historic <br />breeding range extended from central Illinois northwestward through northern Iowa, western <br />Minnesota, northeastern North Dakota, southern Manitoba and Saskatchewan, and the <br />general vicinity of Edmonton, Alberta, to the present nesting area of Wood Buffalo National <br />Park (Wood Buffalo), Northwest Territories in Canada (USFWS 1994). Winter distribution <br />was primarily along the Gulf of Mexico from Louisiana to northeastern Mexico. There were <br />several migration routes, including a lesser migration route to wintering areas along the <br />Atlantic Coast. Some whooping cranes were believed to have migrated to interior Mexico, <br />following the migration route of sandhill cranes. The total population of whooping cranes as <br />of 1869 was estimated at approximately 1,300 birds (Allen 1952). Two other estimates put <br />the 1870 population at between 500 and 700 birds (USFWS 1994, Cannon 1996). By 1937 <br />only two small breeding populations survived: A non - migratory group of about 10 -15 birds <br />in southwestern Louisiana, and the flock known as the Aransas -Wood Buffalo population <br />which included about 20 migratory whooping cranes (McIlhenny 1938, Lynch 1984, Cannon <br />1996, Drewien et al. 2000). This section focuses on the Aransas -Wood Buffalo migratory <br />population. <br />Aransas -Wood Buffalo Whooping Crane Population Estimates <br />The size of the Aransas -Wood Buffalo migratory population has increased from 18 in 1938- <br />1939 (USFWS 1994) to 180 birds in 2000 -2001 (W. Jobman, pers comm.). Whooping crane <br />census information from 1938 -2000 is shown in Table 1. The peak count of 188 occurred in <br />1999 -2000 and the low count of 16 occurred in 1941 -1942 (USFWS 1994, W. Jobman pers. <br />comm.). <br />Aransas -Wood Buffalo Whooping Crane Migration <br />Spring migration from Aransas National Wildlife Refuge begins as early as March 7 (Wally <br />Jobman, unpublished data in Austin and Richert 2001). Some cranes have been observed <br />earlier in Oklahoma Nebraska and Kansas (February to early March) and it is assumed that <br />these birds wintered in a location other than Aransas, Texas. The earliest whooping crane <br />observation in Nebraska occurred on February 10 and the latest spring migrant was observed <br />on May 23 (reference to data table). The peak migration, based on the median date of <br />spring migration occurrence in Nebraska is April 12th (Austin and Richert 200 1) with the 10th <br />and 90th percent confidence intervals being March 29 and April 24 for the time period 1975- <br />1999 (Austin and Richert 2001). <br />Fall migration from Wood - Buffalo, Canada begins in September, with the earliest <br />observation in the United States being in North and South Dakota in early September. The <br />earliest fall migrating whooping crane observation in Nebraska occurred on October 1 and <br />the latest fall migrant was observed on November 21 (reference). The peak migration, based <br />on the median date of fall migration occurrence in Nebraska is October 27th (Austin and <br />Richert 2001), with the 10th and 90th percent confidence intervals being October 17 and <br />Draft Baseline Report — Whooping Crane Section 4 <br />