Alternative reproductive tactics in male eastern gray squirrels: “making the best of a bad job”

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Abstract
Male eastern gray squirrels (Sciurus carolinensis) congregate around and pursue a female on her single day of estrus. The tactics of uniquely marked adult males were monitored during winter mating bouts from 1986 to 1990 to examine variation in male copulatory success. Two tactics were chosen by males: active pursuit or satellite. Active-pursuit males were dominant and defended proximity to females. Satellite males were subordinate and remained dispersed in the female's home range. Active pursuit was used only by males ≤2.75 years old. The switch point between the tactics is about 3 years. Copulations were not distributed evenly among males, with about 30% of all adult males failing to copulate during a breeding season. Active pursuit was the most successful strategy, with male success attributed to the ability to defend access to the female. However, satellite males successfully copulated due to the escape of females from dominant males. Females appear to avoid the overt aggression characteristic of the competition among active-pursuit males by running from the group of males. Male success after a female's breakaway was evenly distributed between the two tactics and accounted for all copulations by satellite males. The activepursuit and satellite tactics appear to be a conditional evolutionarily stable strategy where young, subordinate males are “making the best of a bad job”.

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