rie dogs, and perhaps female Utah prairie dogs as well, rear
larger litters after copulating with several males. Another
reason is that monopolization of estrous females by males
is probably easier for black-tailed prairie dogs than for
Gunnison’s and Utah prairie dogs. Factors that affect the
monopolization of estrous females include visibility within
the home territory, number of entrances per mating burrow,
and reproductive synchrony among females.
Nonparental infanticide among black-tailed prairie dogs
involves killing by adults of both sexes, and affects 39% of
litters. Infanticide among Gunnison’s prairie dogs, by con-
trast, is exceedingly rare. Among Utah prairie dogs, infan-
ticide involves killing by adult males only, and affects 15%
of litters. Reasons for these striking interspecific differences
are elusive.450 Chapter Thirty-Seven