. 45° 40° 35° 30° 25° 115° 110° 105° 100° 95° 90° 85° 80° m. :'. -DisiTilniliniis ol tlic avcniijf niimhir (il lanlcs ohsitMil (mt coimi duniiK ilic iiuiluiiilci siirvcvs. HITD-HISl' ( Hmfi: ipMiKlil. 1 li>- Wikllilc Socifiy). A majority of eagles seen during the winter inventory was associated with the Mississippi River floodplain. Since 1973, nunil)ers of eagles tensused in Januaiv along the Illinois River usually ranged between 100 and 300, with a maximum of 383 observed in l'.)8(). Ihe percentage of all eagles censused by the I NHS during January that were immatures ranged
. 45° 40° 35° 30° 25° 115° 110° 105° 100° 95° 90° 85° 80° m. :'. -DisiTilniliniis ol tlic avcniijf niimhir (il lanlcs ohsitMil (mt coimi duniiK ilic iiuiluiiilci siirvcvs. HITD-HISl' ( Hmfi: ipMiKlil. 1 li>- Wikllilc Socifiy). A majority of eagles seen during the winter inventory was associated with the Mississippi River floodplain. Since 1973, nunil)ers of eagles tensused in Januaiv along the Illinois River usually ranged between 100 and 300, with a maximum of 383 observed in l'.)8(). Ihe percentage of all eagles censused by the I NHS during January that were immatures ranged between and (Table 3). In a majority of the years, the percentage of immature eagles varied between 30 and 37%. Southern (1963) cautioned, however, against using the proportion of immatures to adult eagles wintering in the Mississippi Valley bordering Illinois as a realistic estimate o( leprochu live suctess. Millsap (1986:436) re])orted that the jjercfiitage of imiTiature bald eagles observed on the midwintei sur- vey from 1979 to 1982 varied between and 4 . Sprunt (1965) reported that estimates of inimatuie bald eagle age ratios ranged between 21.(j and from surveys (ondiKterl by the National AudulK)n Society from 1961 to 1963. The counts compiled by Elton Fawks were both aerial and ground (ounts (Table 3). count in- (hided the Mississippi Ri\ei from I)ubu(|ue to "below St. Louis," the Illinois Rivei, and vaiying numbers and combinations of refuges and reservoirs. The Mis- sissippi River from (Irafton to was added in 1976. The 1982 count also included the Fox. Wabash, Rock, and Ohio rivers. Fiom 1961 to 1978, the count was maove. but thev do not concen- tiatc- on . neai large rivers where bald eagles are
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Keywords: ., bo, bookcentury1900, bookcollectionbiodiversity, bookleafnumber15
