Vol. 25, No. 6 
Page 2 
1 
Ecology and Management of Squirrels - W-66-R C. M. Nixon, 
L. P. Hansen 
In last month's newsletter we hypothesized that intrinsic mechanisms closely 
tuned to the density of squirrels regulate fox squirrel densities. To test this 
hypothesis we designed a field experiment using 7 separate oak-hickory dominated 
plots. During fall 1979, we livetrapped and removed (1) all captured males from 
2 plots (Allerton B and Busch), (2) all captured females from 2 plots (Allerton 
A and C), and (3) all captured fox squirrels from 1 plot (Allerton D). For 
controls, we monitored 2 woodlots (Trelease and Brownfield) from which fox 
squirrels had not been removed. 
Fox squirrels captured elsewhere were released on all of the experimental 
and control plots in fall 1979 to serve as introduced ,f immigrants." Each study 
plot was retrapped without removal during spring 1930 to determine recapture and 
reproductive rates of resident and introduced squirrels and the rates of 
recruitment of new squirrels. Regardless of prior removals, few of the released 
squirrels were recaptured on the same plots where they were released. Therefore, 
we discontinued attempts to artificially introduce immigrants onto the study 
plots. We also ceased using Trelease and Brownfield woodlots as controls because 
the structure and composition of plant species on these plots differed markedly 
from the experimental plots. 
An additional grid (Allerton E) was set up as a control during fall 19$0. 
Removal during the fall and retrapping during the spring occurred during 1930—31 
and 1981-32 as in 1979-80 except that only the adult segment of the population 
was removed. In next month's newsletter we will begin discussion of some of the 
results of this experiment. 
Responses of Prairie Chickens to Habitat Ma nipulation - W-66-R R.L. Westemeier, 
J.E. Buhnerkempe 
Included in the annual census of prairie chickens this spring, as in 1981, 
was a census of pheasants on the Bogota Study Area; standard census methods were 
used. As in the past 19 years, a block of some 32 mi (81.9 km ) that included 
the prairie chicken sanctuaries near Bogota was surveyed beginning about l April, 
primarily to locate booming prairie chickens. The survey was extended into early 
May, the peak crowing season for pheasants, in 1981 and 1982. A special effort 
was made to triangulate each crowing cock pheasant on the sanctuaries by making 
frequent listening stops and by listening for 4 minutes instead of the standard 
2 minutes at each stop. 
We estimated 46 crowing cock pheasants on the 32-section block this spring 
(30 cocks on or very near the sanctuaries and 16 cocks away from the sanctuaries 
on private lands), which is essentially the same population level and distribution 
of pheasants as in spring 1981 (MWRL 25(2):2-3). Comparative densities of 
pheasant cocks are 18.8 per mi * 2 (2.6 km 2 ) for the 1.6 mi 2 (4.1 km 2 ) of sanctuaries 
and 0.5 per mi 2 for 30.4 mi 2 (77*8 km 2 ) of private land. The pheasants at Bogota 
continue to be essentially a local population that is strongly dependent upon 
sanctuary habitat. 
