Distribution and abundance of winter Distribution and abundance of winter populations of bald eagles in Illinois distributionabun129have Year: 1988 Illinois Natural History Survey Biological Notes No. 129 Southeast Alaska Northwest Interior Maine/ Nova Scotia I \\ Florida Breeding Area Represented by Bandings Fig. migraioi \ |)'l) Scrviii- 1986) Oilohii icmM-rics (IS. lisli . U ildlile most likely to occur. Areas covered in the Christmas bird counts are generally those surroimding the loca- tion of local Audubon Society chapters. Bald eagles observe
Distribution and abundance of winter Distribution and abundance of winter populations of bald eagles in Illinois distributionabun129have Year: 1988 Illinois Natural History Survey Biological Notes No. 129 Southeast Alaska Northwest Interior Maine/ Nova Scotia I \\ Florida Breeding Area Represented by Bandings Fig. migraioi \ |)'l) Scrviii- 1986) Oilohii icmM-rics (IS. lisli . U ildlile most likely to occur. Areas covered in the Christmas bird counts are generally those surroimding the loca- tion of local Audubon Society chapters. Bald eagles observed on the Christmas bird counts ranged from 256 in 1974 to 767 in 1986 (Table 3). Differences in dates of counts, areas coveted, skills of observers, and weather conditions and the emphasis placed on counting eagles as opposed to other species create variability among the inventories (Table !5). Whereas counts for a single year vary widely, there are several instances when the changes between years are similar. Kxamiiiation of eagle numbers in Table 3 reveals that both the INHS and Fawks inventories show intreases from 1961 to 1962, decreases from 1962 through 1964, and increases fiom 1964 to 1965 and from 1977 tiirough 1979. Such similarities in trends suggest that patterns of changes in eagle nimi- bers in Illinois are real and demonstrate the impor- tance of more than one type of amnial count. Moving .3-year averages of the aiuuial winter
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