. Distribution and abundance of winter populations of bald eagles in Illinois. Bald eagle. I 15 29 12 DEC JAN Fig. numbci of bald eagles counted per invenloiv in ihe Upper Illinois River Region. 197( Seasonal patterns of hald eagle octiirrence in the Central Illinois Rivei Region are ilhistiated in Figure 20. No census tliglits were toiuhuied from mid-. Peak population counts occurred between 3 Janu- ary and 9 March in this region with the highest count of 53 eagles reported on 20 January 1982. Generally, fewer than 25 eagles were seen on each census in this region. Immature b


. Distribution and abundance of winter populations of bald eagles in Illinois. Bald eagle. I 15 29 12 DEC JAN Fig. numbci of bald eagles counted per invenloiv in ihe Upper Illinois River Region. 197( Seasonal patterns of hald eagle octiirrence in the Central Illinois Rivei Region are ilhistiated in Figure 20. No census tliglits were toiuhuied from mid-. Peak population counts occurred between 3 Janu- ary and 9 March in this region with the highest count of 53 eagles reported on 20 January 1982. Generally, fewer than 25 eagles were seen on each census in this region. Immature birds consisted of 0 to of the eagles observed on individual inventories, and the av- erage proportion of immatures for all eagles seen was The mean number of bald eagles observed per inventory for individual areas is depicted in Figure 19. The downstream portion of this region, between La Salle, Illinois, and Spring Valley, Illinois, was gen- erally used the most by eagles (Appendix). The density of bald eagles in the Upper Illinois River Region av- eraged per river mile or per square mile of Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Havera, Stephen P; Kruse, Glen W. [Champaign, Ill. ] : Illinois Natural History Survey


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