. 10,00 Fig. 17.—Mean niniiljer ol bald eagles counted per inventory at census areas within the Lower Mississippi River Region, 1972-1986. or per square mile of wetland habitat. These density values of bald eagles were the lowest of all the Mississippi Ri\er regions. Upper Illinois River Region. The L^pper Illinois River Region stretches from Morris, Illinois, to near Spring Valley, Illinois (Fig. 6). Most portions of this region were surveyed 59 times between September and .-Vpril from 1976 to 1985. This relativelv short, highly de- veloped segment of the Illinois River vallev seldom sho
. 10,00 Fig. 17.—Mean niniiljer ol bald eagles counted per inventory at census areas within the Lower Mississippi River Region, 1972-1986. or per square mile of wetland habitat. These density values of bald eagles were the lowest of all the Mississippi Ri\er regions. Upper Illinois River Region. The L^pper Illinois River Region stretches from Morris, Illinois, to near Spring Valley, Illinois (Fig. 6). Most portions of this region were surveyed 59 times between September and .-Vpril from 1976 to 1985. This relativelv short, highly de- veloped segment of the Illinois River vallev seldom showed substantial use bv bald eagles. The seasonal pattern of eagle numbers in the Upper Illinois Ri\er Region is shown in Figure 18. The trend toward earlier observations of eagles in the fall during the years inventoried was also apparent in this legion. In the late 1970s, eagles were usually first seen during aerial inventories in the latter half of November, but in more recent years, the first observa- tions generalh occurred in mid-October. The earliest sighting ot bald eagles during any census in all regions (F"ig. 6) occurred in the LIpper Illinois Ri\er Region when four birds were seen between L'tica ami Mar- seilles on 10 September 1980. Spring departure ot eagles from the L'i)per Illinois Ri\er Region was gen- erall\ completed b\ earK .\piil.
Size: 1867px × 2678px
Photo credit: © The Bookworm Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionbiodiversity, bookcontributoruniv
