Animals must forage to acquire energy for survival and reproduction, yet foraging exposes them to predators. This creates a trade-off between energy intake and safety that shapes behavior, wherein the mere perception of predation risk can create a “landscape of fear.” Within this trade-off, both risk and energetic needs vary, shifting the balance and favoring different foraging strategies. Using Neotropical electric fish as a study system, I investigated how foraging under predation risk is shaped across biological scales, including environmental dynamics, interspecific differences, species-level traits, and intraspecific variations. These nocturnal fish emit continuous electric signals to sense the environment, and recording these signals allows passive monitoring of activity. They typically avoid light, making moonlight a quantifiable proxy for perceived risk. I first developed a R package and hardware system to predict and recreate moonlight cycles. Next, I tested whether eye size, a proxy for visual acuity, predicts interspecific differences in moonlight responses by deploying loggers in an Amazonian stream. Smaller eyes predicted stronger moonlight avoidance, whereas a large-eyed species lacked a moonlight response entirely. I then investigated the timing mechanisms of the sand knifefish, discovering that exogenous and endogenous mechanisms interact to guide activity across the complex moonlight cycle by dynamically tracking shifting dark periods. Lastly, I tested how risk-taking is influenced by body condition and life stage. In captive experiments, adults—but not juveniles—became more risk-prone as condition decreased. Collectively, this research shows how factors across biological scales shape animal behavior within a dynamic nocturnal landscape of fear.
Lok Poon
Dr. William Crampton, Advisor
Read More