Figure 13.2 (A) Infanticide during the lactation period of Belding’s ground squirrels. Reproductive females aggressively defend territories against conspecifics that
may attempt to abduct and kill their young. (B) Space constraints early in the active season of Belding’s ground squirrels when females are pregnant. Much of the
squirrels’ habitat is covered by snow, and females aggressively compete for space available for establishing maternal territories.
A B
Figure 13.3 Possible assistance from mothers in establishing maternal territo-
ries among female Belding’s ground squirrels. Aggressive behavior among year-
ling females occurs at lower (A) rates and (B) intensity than it does in experienced
females. During gestation, when females establish maternal territories, squirrels
with yearling daughters setting up a territory nearby exhibit higher rates of ag-
gression toward unrelated squirrels than do experienced females without yearling
daughters. Intensity scores for aggressive interactions were assigned as follows:
threat —1; chase 5 m —2; chase 5 m —3; attack— 4. Data were evaluated
with ANOVA, and post-hoc comparisons were performed with Tukey’s tests. Dif-
ferent lower case letters indicate significant differences (P0.05) between
groups. Two yearling females represented in the graph had the same mother.
Figure 13.4 (A) Rates and (B) intensity of vigilant behavior among female
Belding’s ground squirrels during the breeding cycle. Although rates of vigilance
did not differ among females, vigilant behavior tended to be more acute among
females with yearling daughters nearby. Intensity scores for vigilant behavior
were assigned as follows: resting alert —1; posting (standing on hind legs)—
3; alarm calling —5. Females were awarded an additional point if vigilant behav-
ior occurred on an elevated post such as a rock or fallen tree. Data were evalu-
ated with ANOVA, and post-hoc comparisons were performed with Tukey’s tests.
Different lower case letters indicate significant differences (P0.05) between
groups. Two yearling females represented in the graph had the same mother.