Resource attractiveness of the male beaugregory damselfish and his decision to court or defend

We examined the decisions territorial male beaugregory damselfish (Stegastes leucostictus) make when presented with mating and aggressive situations simultaneously. Specifically, we tested how males responded to simultaneous and consecutive presentations of conspecific males and females in bottles. We hypothesized that (1) territorial males would show lower levels of courtship toward females when a competing male is also present compared to when only the female is present and (2) territorial males would show higher levels of aggression toward intruding males when a female is also present on their territories than when only the intruder is present. We predicted that males with high-quality breeding sites would court females and attack competitors more vigorously than males with low-quality breeding sites. Males on low-quality breeding sites exhibited fewer conspicuous courtship displays toward bottled females and a lower bite rate toward bottled males than did the males on high-quality breeding sites. We concluded that poor breeding-site quality was responsible for the decline in the most conspicuous aspects of both courtship and aggression. When presented simultaneously with a bottled male and a bottled female, defenders of both breeding-site types drastically reduced the number of courtship displays and the amount of time they spent near the female. Thus, all aspects of courtship were reduced in the presence of a male intruder. Time spent near the bottled male also decreased in these simultaneous presentations; however, this decrease was less dramatic than the reduction in time spent near bottled females. Habitat quality did not affect these trade-off decisions, but the bite rate exhibited toward the bottled male increased in the simultaneous presentations compared to the single presentations. Due to this increase in a territorial male's defensive behavior when a female is present, we conclude that the presence of a female temporarily increased the value of a territory. We suggest that the possible loss of a territory to an intruding male takes priority over the potential benefits of successfully courting a single female and that it is a male's future reproduction, as well as his current reproduction, by which he assesses his benefits.