Where the fiddlers sing: fiddler crabs change their tunes depending on the context

Males of the fiddler crab Austruca lactea exhibit drumming behaviour as vibroacoustic communication and wave their enlarged claw for courtship. However, we identified that they also perform drumming as an agonistic behaviour. To determine whether vibrational characteristics differ depending on context, we compared five drumming parameters (pulse rate, pulses per train, train duration, pulse duration and dominant frequency) between courtship and agonistic contexts. We found that courtship drumming had a longer train duration, with more pulses per train than agonistic drumming. However, agonistic drumming had a higher pulse rate than courtship drumming. Pulse duration and dominant frequency did not differ significantly between contexts. Therefore, fiddler crabs' vibrational signals might have evolved into two different signals, for agonistic and courtship interactions.(c) 2023 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.