Patrolling the area, not ousting intruders, relates to reproductive success for territorial male Leon Springs pupfish, Cyprinodon bovinus.

We considered the relationship between the benefits and costs of territorial defense in a wild population of the Leon Springs pupfish, Cyprinodon bovinus. We defined benefit as the number of eggs deposited on an artificial substratum placed within the defender's territory. Costs included two defensive behaviors.

Changing tactics: dominance, territoriality, and the responses of "primary" males to competition from conditional breeders in the variegated pupfish (Cyprinodon variegatus).

Using variegated pupfish, we examined the flexibility in "primary" male tactics when dealing with the aggressive costs of competition. Analogous to conditional mating strategies, we expected primary males to exhibit one of two interrelated tactics (i.e.