236 
Ferguson & Bohlen 
Table 5. Survivorship of juvenile spiny lizards on “crowded” versus “noncrowded” sectors 
of a 4-acre study area in Pottowattomee Co., Kansas. Significant differences between sur- 
vivorships on crowded and noncrowded sectors are indicated as follows: *p<.05 (Chi squared 
test) . 
# of Lizards at 
Beginning of 
Interval Not 
Surviving to 
End of Interval 
# of Lizards at 
Beginning of Proportion 
Interval Surviving Surviving to 
to End of Interval End of Interval 
1971 A. Late July to Late August Interval: 
# of crowded sectors 
(>12 lizards/6400 ft.“) 
5 
45 
59 
.57 
# of noncrowded sectors 
( <12 lizards/6400 ft.^) 
14 
43 
72 
.63 
1971 B. Late August to Late September Interval: 
# of crowded sectors 
(>13 lizards/6400 ft.^) 
6 
40 
87 
.69 
# of noncrowded sectors 
( <13 lizards/6400 ft.^) 
14 
35 
74 
.68 
1972 A. Late July to Late August Interval: 
# of crowded sectors 
(>4 lizards/6400 ft.^) 
8 
18 
21 
.54 
# of noncrowded sectors 
( <4 lizards/6400 ft.^) 
12 
14 
10 
.42 
1972 B. Late August to Late September Interval: 
# of crowded sectors 
(>3 lizards/6400 ft.^) 
8 
23 
14 
.38 
# of noncrowded sectors 
( <3 lizards/6400 ft.^) 
* 
12 
6 
13 
.68 
However, additional circumstantial evi- 
While this does not prove 
that resource 
dence suggested that there was a possible 
competition was increasing, such a change in 
seasonal increase in resource 
competition. 
availability would certainly 
accompany an 
Food availability per lizard clearly was de- 
creasing during the hatching season (Table 
6). Thus, while lizard numbers increased 
from 60 to 90 from early August to October, 
1972, the density in the habitat of those 
insect species also found in the intestinal 
tract of lizards decreased during September 
to 44 percent of the level of early August. 
increase in competition. While predation is 
probably an important source of mortality, 
we suspect that an interaction between pre- 
dation and competition similar to that sug- 
gested by the data of Fox (1973) on Uta 
stansburiana may be causing the observed 
pattern of mortality and density change. 
