Structural complexity but not territory sizes influences flight initiation distance in a damselfish

Abstract

The fear of predators can lead to behavioral changes in their prey, but animals must trade off defensive behavior against other compelling needs. For territorial species, responding to predators may be especially costly, because defense and escape are mutually incompatible. A growing literature documents risk assessment in fish, but a few studies have focused on extremely territorial fish, and nothing is known about how territory size, territorial interactions, habitat structural complexity, and life stage may modify risk assessment. We studied this in a damselfish (Stegastes fuscus) on coral reefs and measured risk assessment using flight initiation distance (FID). We found that only structural complexity explained variation in FID; fish in more complex habitats tolerated closer approach. Our study suggests that individuals in relatively more structurally complex territories are bolder than those that occur in less complex territories. Documenting the relative importance of these variables is important, because antipredator behavior influences not only the predator–prey relationship, but can also generate cascading effects, and influence the structure of the community and potentially entire ecosystems.