The high-output singing displays of a lekking bat encode information on body size and individual identity
A growing body of research suggests that songs are an important part of the courtship behavior of many bat species, however there is little information on the basic characteristics of these vocalizations, or how they may function as a courtship signal. Lekking male lesser short-tailed bats (Mystacina tuberculata) appear to use vocal displays as a primary method for attracting mates, but it is unclear if these vocalizations constitute songs, and what characteristics females may use for mate selection. We recorded 16 lekking males and described the frequency and temporal properties of their vocalizations. We identified four notes (upsweeps, downsweeps, trills, and tones) that comprise courtship vocalizations, and males produced these notes either singly, or combined them linearly to form composite syllables. We classified 51 distinct syllable types (with an average of 29 types per male), with four (trills, upsweep-trills, trill-downsweeps, and upsweep-trill-downsweeps) comprising 69% of all syllables produced. The duration of trill-downsweeps scaled negatively with forearm length (a proxy for body size in bats), and all four main syllable types showed evidence of individuality. Based on the behavioral characteristics and contexts of these courtship vocalizations, we posit that this behavior constitutes singing. Furthermore, M. tuberculata potentially has one of the highest sustained song outputs yet described. Our results suggest the singing displays of M. tuberculata are signals that provide useful, honest cues of male characteristics and identity to females, and are as complex as the songs of many passerines.
Male courtship displays are predicted to honestly advertise aspects of male traits. Like many birds, some bat species produce songs to attract mates, but the characteristics of these songs are not well understood within the context of sexual selection. We demonstrate that the courtship vocalizations of Mystacina tuberculata – a species that likely relies on singing as its primary method of mate attraction – are a complex set of signals. Males have large syllable repertoires, encode four of their most-common syllables with individual signatures, and have one of the highest recorded song outputs for either birds or bats. Moreover, the length of one of the most commonly used syllable types is inversely related to male size, providing females the opportunity to appraise male size by auditory cues alone. Our work is part of a growing body of research demonstrating singing behavior in bats.
KeywordsAllometry Chiroptera Courtship Lek breeding Sexual selection Song
We are grateful to the New Zealand Department of Conservation – particularly T. Thurley and D. Smith – for assistance and support. We thank R. Germain for statistical advice, and three anonymous reviewers for their comments on previous versions of this manuscript.
Funding was provided by the Australasian Society for the Study of Animal Behaviour, the Australasian Bat Society, Bat Conservation International, and the University of Auckland.
Compliance with Ethical Standards
Conflict of Interest
The authors declare that they have no conflict of interest.
All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. The capture and marking of individuals was approved by both the University of Auckland Animal Ethics Committee (permit AEC#000920) and the New Zealand Department of Conservation (High Impact Research and Collection Permit WK-32184-RES).
- Bohn K, Montiel-Reyes F, Salazar I (2016) The complex songs of two Molossid species. In: Ortega J (ed) Sociality in Bats. Springer, Switzerland, pp 143–160Google Scholar
- Bradbury JW, Vehrencamp SL (1998) Principles of animal communication. Sinauer Associates Inc., Sunderland, MAGoogle Scholar
- Catchpole CK, Slater PJB (2003) Bird song: biological themes and variations. Cambridge University Press, Cambridge, UKGoogle Scholar
- ESRI (2012) ArcMap 10. Environmental Systems Research Institute, Redlands, CAGoogle Scholar
- Kroodsma D (2005) The singing life of birds: the art and science of listening to birdsong. Houghton Mifflin Harcourt, New YorkGoogle Scholar
- Marler P (2004) Science and birdsong: the good old days. In: Marler P, Slabbekoorn H (eds) Nature's Music: the science of birdsong. Academic Press, New York, pp 1–38Google Scholar
- Marler P, Slabbekoorn H (2004) Nature's music: the science of birdsong. Elsevier Academic Press, San Diego, CaliforniaGoogle Scholar
- Pollak GD, Casseday J (2012) The neural basis of echolocation in bats. Springer, BerlinGoogle Scholar
- R Core Team (2013) R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna. https://www.R-project.org/
- Revelle W (2018) Psych: Procedures for Personality and Psychological Research, Northwestern University, Evanston, Illinois. https://www.CRAN.R-project.org/package=psychVersion=1.8.3
- Rice WR, Gaines SD (1994) ‘Heads I win, tails you lose’: testing directional alternative hypotheses in ecological and evolutionary research. TREE 9:236–237Google Scholar
- SAS Institute Inc. (2016) JMP Pro 13. Cary, NC: SAS Institute Inc.Google Scholar
- Smarsh GC, Smotherman M (2015) Singing away from home: Songs are used on foraging territories in the African megadermatid bat, Cardioderma cor. In: Proceeding of Meetings on Acoustics 25:010002. Acoustical Society of America, JacksonvilleGoogle Scholar
- Sokal RR, Rohlf FJ (1995) Biometry: The principles and practice of statistics in biological research. W.H. Freeman and Co., New YorkGoogle Scholar
- Vehrencamp SL (2000) Handicap, index, and conventional signal elements of bird song. In: Espmark Y, Amundsen T, Rosenqvist GO (eds) Animal signals. Tapir Academic Press, Trondheim, Norway, pp 277–300Google Scholar
- Wells KD (2010) The ecology and behavior of amphibians. University of Chicago Press, ChicagoGoogle Scholar