Larger but not louder: bigger honey bee colonies have quieter combs

Communication is impossible if the sender's signal cannot overcome background noise to reach the receiver. This obstacle is present in all communication modalities, forcing organisms to develop diverse mechanisms to overcome noise. Honey bees will modify combs to improve signal efficiency of substrate-borne vibrations, but it is unknown whether, and if so, how, bees compensate for the largest potential source of noise: the bees themselves. The number of bees in a colony changes markedly throughout the year, but the size of the nest cavity does not, forcing workers into high densities on the combs. How, then, do bees communicate via substrate-borne vibrations on combs that are covered in bees? We used accelerometers to measure comb vibrations, while varying the number of workers on the comb. Surprisingly, comb vibrations decreased with increased worker number. Furthermore, inserting freshly killed bees to the comb demonstrated that it is not simply the bees' collective mass that damps vibrations, but is probably their behavior. We propose that their posture damps vibrations, with each bee linking up to six neighboring cells with her legs. This collective damping reduces background noise and improves the landscape for communication. These results demonstrate how living systems, including superorganisms, can overcome physical obstacles with curiously simple and elegant solutions. Background noise is a pervasive problem in communication. Honey bees must address this problem because thousands of individuals occupy and communicate within a single nest made of beeswax combs. While it is known that bees use beeswax comb vibrations to communicate, it is unknown how they overcome background noise when the combs become covered in bees. We show that comb vibrations decrease, not increase, as the number of bees on the comb increases. This unexpected result is not due to bees' mass, but rather their interactions with the comb that damps vibrations. By reducing background vibrations, workers make the comb "quieter" and improve the substrate for communication. Therefore, we show that the communication landscape for sending signals within the superorganism is improved, not hindered, as the colony grows.