Meeting Abstract

P3-98   -   Mayfly swarming flight behavior limits male-male interaction Fabian, ST*; Rodrigo-Gonzalez, C; Lin, HT; Bioengineering, Imperial College London, UK; Bioengineering, Imperial College London, UK; Bioengineering, Imperial College London, UK s.fabian@imperial.ac.uk http://www.samueltfabian.com

Mayfly swarms are a spectacular early summer event in temperate latitudes. While exact swarming behaviors vary, a common feature of mayfly swarms is the bobbing of males, in which individuals oscillate between near-vertical climbs and parachuting descents. We investigated the flight behavior of swarms of common mayflies (Ephemera vulgata) for principles underpinning their conspecific pursuits, and thus the potential functionality of in-flight bobbing. We found that male mayflies operated an inexact filter on pursuit targets, readily chasing passing birds, other insects, or any thrown object. Absolute motion is not even required for the target, as males pursued and attempted to mate with suspended stationary black spheres. We summarize that male mayflies apply the most basic of contrast filters, with any object in the airspace above them being considered a target. To contrast this simple filter, mayflies do not simply pursue the target’s current location, but intercept it by flying toward a future meeting point, resembling the flight of dragonflies and other predatory insects. Interception is the fastest way to reach a non-maneuvering target, suggesting that being the first to couple cruising females is imperative. The loose target filter may result in faster interception of females, but also means more frequent mistaken chases of other males. We suggest that vertical bobbing flight creates specific visual statistics and reduces males flying above on another, thus reducing the likelihood of unnecessary male-male interactions. Males also frequently aborted chases when targets dropped below them in altitude, thus the constant switching between climb and descent phases may further disrupt unproductive male-male chases.