Meeting Abstract
Common Poorwills (Phalaenoptilus nuttallii) are nocturnal insectivorous birds that have a sit-and-wait predation strategy. They wait for an insect to fly overhead, then fly up and catch it in their beak. P. nuttallii have several wing and feather features that are hypothesized to reduce their locomotion-induced sounds, aiding in silent flight. These specialized features include a velvety dorsal surface and vane fringe, both present on flight feathers. There are two hypotheses for the evolution of silent flight: prey detection and stealth. The prey detection hypothesis predicts that silent flight evolved to reduce the sounds generated by locomotion, improving a predator’s ability to acoustically locate prey. The stealth hypothesis predicts silent flight evolved to help predators launch surprise attacks. The prey detection hypothesis predicts that the predator relies on auditory cues to hunt. However, P. nuttallii is not known to hunt acoustically and their eye morphology and hunting behavior suggest that they may be primarily visual hunters. Therefore, we hypothesize that silent flight evolved in P. nuttallii to aid in stealth. Silencing features may reduce ultrasound by dampening the sounds produced when two feathers rub together, allowing P. nuttallii to avoid detection by hearing insects while hunting. We assess hypotheses of how flying insects may detect an approaching predator, and how likely it is that silencing features present on P. nuttallii wings aid in a stealthy hunting strategy. We recorded P. nuttallii hunting in the wild with an infrared camera to quantify their feeding behavior and the behavior of their intended prey during an attack.
