title: How effective are acoustic signals in territorial defence in the Lusitanian toadfish?
abstract: The function of fish sounds in territorial defence, in particular its influence on the intruder's behaviour during territorial invasions, is poorly known. Breeding Lusitanian toadfish males (Halobatrachus didactylus) use sounds (boatwhistles) to defend nests from intruders. Results from a previous study suggest that boatwhistles function as a 'keep-out signal' during territorial defence. To test this hypothesis we performed territorial intrusion experiments with muted Lusitanian toadfish. Males were muted by making a cut and deflating the swimbladder (the sound-producing apparatus) under anaesthesia. Toadfish nest-holder males reacted to intruders mainly by emitting sounds (sham-operated and control groups) and less frequently with escalated bouts of fighting. When the nest-holder produced a boatwhistle, the intruder fled more frequently than expected by chance alone. Muted males experienced a higher number of intrusions than the other groups, probably because of their inability to vocalise. Together, our results show that fish acoustic signals are effective deterrents in nest/territorial intrusions, similar to bird song.
authors.affiliation: MARE - Marine and Environmental Sciences Centre, ISPA Instituto Universitário, 1149-041 Lisboa, Portugal.
authors.forename: Carlotta
authors.initials: C
authors.lastname: Conti
authors.affiliation: Departamento de Biologia Animal, cE3c - Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal.
authors.forename: Paulo J
authors.initials: PJ
authors.lastname: Fonseca
authors.affiliation: Facoltà di Scienze Matematiche, Fisiche e Naturali, Dipartimento di Biologia - CSEE, University of Trieste, 34127 Trieste, Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Picciulin
authors.affiliation: MARE - Marine and Environmental Sciences Centre, ISPA Instituto Universitário, 1149-041 Lisboa, Portugal amorim@ispa.pt.
authors.forename: M Clara P
authors.initials: MC
authors.lastname: Amorim
mesh_terms: D000162:Acoustics; D000818:Animals; D024541:Batrachoidiformes / Q000502:physiology*; D008297:Male; D013731:Territoriality; D014828:Vocalization, Animal
keywords: Batrachoididae; Halobatrachus didactylus; Muting experiments; Sound production; Teleost fish; Territorial behaviour; ‘Keep-out’ signal