Z T.H Ev A, UD) U B30 NB Lae 
MISSISSIPPI RIVER DAM 12 
RIVER ROAD 
Figure 1. The study area extended for 14 miles along the Mississippi River, its back- 
waters and sloughs. River Road parallels the main channel for some distance and 
Crooked Slough thereafter. We also traveled two side roads, one of which went to 
Lock and Dam 12, during our census trips. We censused the birds during 41 of the 
53 days spent in the area. Areas of major eagle concentrations are marked on the 
map (A, B, C, D); these areas corresponded with open holes in the frozen river sys- 
tem. We observed additional eagles between these areas. Most of the terrain border- 
ing the river was forested. 
Figure 2. We often observed from one to 
ten eagles in a single tree. Usually they 
were in the open parts of trees where 
limbs were sturdy. Large trees in semi- 
open situations were preferred for loafing 
areas, but smaller trees in dense forest 
stands were occasionally used while the 
birds were feeding. The adults have wing- 
spreads of about seven feet. 
Deer and other mammals (e.g., beaver, 
muskrats, and foxes) were abundant in 
the area. Numerous birds were also in 
the vicinity (e.g., Pileated Woodpeckers, 
Red-shouldered Hawks, and many passer- 
ine species.) 
( 
Figure 3. We occasionally observed 
eagles in dense forest growths along small 
sloughs. Never were more than three or 
four birds present at one time. The larg- 
est number of immatures observed during 
a single census was 15. The proporticn of 
adults (peak number 254 on February 2): 
to the largest number of immatures (15 on 
February 25) was 17:1. The plumageés of 
immatures varied; some had white under- 
parts; others had white coverts and/or 
white patches on the back. 
