Title: Shaping the acoustic image: How moth tails divert bat attack by altering echoic information

Program: Ecology, Evolution, and Behavior PhD

Committee Chair: Allison Simler-Williamson

Committee: Allison Simler-Williamson, Jesse Barber, Sven Buerki, Akito Kawahara

Abstract: Predator deflection traits can increase survival by altering how predators perceive prey. In insectivorous bats, prey capture depends on echolocation. Bats emit ultrasonic calls and interpret the returning echoes to detect, localize, and track flying insects such as moths. In saturniid moths, elongated hindwing tails divert bat attacks and markedly increase escape success. Yet the acoustic mechanisms underlying this anti-bat strategy remain unresolved. Here, I integrate three complementary approaches to test how moth tails shape the echoic information available to echolocating bats. First, using three-dimensional acoustic imaging of tethered luna moths (Actias luna) in flight, I found that tails generate spatially distinct acoustic glints that are separable from wing reflections. These glints persist across a broad range of imaging geometries, reshaping the temporal and spatial organization of echoes. Second, using a broad comparative dataset of hindwing appendages from moths and butterflies, I found that true saturniid tails occupy a distinct acoustic regime characterized by high angular robustness and low energy asymmetry. This retroreflector-like performance is predicted by integrated three-dimensional morphology, including elongation, dense cup architecture, and broader directional organization of the distal spatulate end of the tail. Third, experimental flattening of luna moth tail tips demonstrates that geometry itself is functionally important. Flattening reduces peak echo intensity, alters the angular distribution of echo energy, resulting in weaker echoes across angles, and increases capture probability in bat predation trials despite no detectable change in bat attack behavior. Together, these results indicate that saturniid hindwing tails are specialized anti-bat sensory structures whose defensive value depends on ultrasonic retroreflective characteristics imparted by complex three-dimensional morphology. Rather than simply strengthening echoes, this morphology reorganizes echo structure in ways that can shape predator perception. More broadly, this project provides a general sensory-ecology framework for understanding how predator perception can shape prey morphology.