title: Silent katydid females are at higher risk of bat predation than acoustically signalling katydid males.
abstract: Males that produce conspicuous mate attraction signals are often at high risk of predation from eavesdropping predators. Females of such species typically search for signalling males and their higher motility may also place them at risk. The relative predation risk faced by males and females in the context of mate-finding using long-distance signals has rarely been investigated. In this study, we show, using a combination of diet analysis and behavioural experiments, that katydid females, who do not produce acoustic signals, are at higher risk of predation from a major bat predator, Megaderma spasma, than calling males. Female katydids were represented in much higher numbers than males in the culled remains beneath roosts of M. spasma. Playback experiments using katydid calls revealed that male calls were approached in only about one-third of the trials overall, whereas tethered, flying katydids were always approached and attacked. Our results question the idea that necessary costs of mate-finding, including risk of predation, are higher in signalling males than in searching females.
authors.affiliation: Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560012, India Post graduate and Research Department of Zoology, The American College, Madurai 625 002, India.
authors.forename: Hanumanthan
authors.initials: H
authors.lastname: Raghuram
authors.affiliation: Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560012, India.
authors.forename: Rittik
authors.initials: R
authors.lastname: Deb
authors.affiliation: Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560012, India.
authors.forename: Diptarup
authors.initials: D
authors.lastname: Nandi
authors.affiliation: Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560012, India rohini@ces.iisc.ernet.in.
authors.forename: Rohini
authors.initials: R
authors.lastname: Balakrishnan
mesh_terms: D000819:Animal Communication; D000818:Animals; D002685:Chiroptera / Q000502:physiology*; D005260:Female; D020387:Food Chain; D008297:Male; D009987:Orthoptera / Q000502:physiology*; D011235:Predatory Behavior; D012306:Risk; D012727:Sex Characteristics; D012726:Sexual Behavior, Animal
keywords: bat predation; bushcrickets; eavesdropping; lesser false vampire; palaeotropics; sex-biased predation