Function of male song in the greater white-lined bat, Saccopteryx bilineata SUSAN M. DAVIDSON & GERALD S. WILKINSON Department of Biology, University of Maryland (Received 14 March 2001; initial acceptance 16 August 2001; final acceptance 13 June 2003; MS. number: A9023) The use of vocalizations by males to attract mates and defend territories is widespread in birds but uncommon in mammals. In the greater white-lined bat, males defend small territories in tree buttresses and produce complex audible vocalizations. During the day, females roost within these territories, and males with females in their territories have higher reproductive success than males without females. To determine call function, we recorded male vocalizations on the island of Trinidad and made behavioural observations of the focal male and nearby bats at the time the calls were given. Noisy broadband calls were directed mainly at other males whereas tonal calls were used primarily in interactions with females. Two other types of calls were given independently of any observable context and may be involved in territorial defence or conspecific notification. Poisson regression showed that males with song repertoires that contained more unique types of composite syllables had more females in their territories. In addition, several acoustic features of one common call type significantly correlated with the number of females on a territory. Male vocalizations may, therefore, transfer information to colony members about male quality or fighting ability. Ó 2004 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. Many male animals have evolved vocalizations that are used in territorial defence, mate attraction, or both; any of these uses of vocalization can strongly affect reproductive success (Bradbury & Vehrencamp 1998). Male vocal displays are well documented in orthopterans (reviewed in Zuk & Simmons 1997), anurans (e.g. Ryan 1980; Arak 1983) and songbirds (reviewed in Catchpole & Slater 1995). Male vocal displays are also found in some marine mammals, such as humpback whales, Megaptera novaean- gliae (Payne & McVay 1971), and several types of seals (Bartholomew & Collias 1962; Stirling & Siniff 1979; Thomas & Stirling 1983; Bartsh et al. 1992; Terhune 1994; Van Parijs et al. 1997). In terrestrial mammals, however, vocal displays are un- common, and many species rely on olfactory or visual dis- plays for mate attraction and territorial defence (Bradbury & Vehrencamp 1998). Primates are one group of terrestrial mammals in which males produce vocal displays for these functions. Male mouse lemurs, Microcebus murinus, use trill calls to attract females (Zimmermann & Lerch 1993), and male gibbons, Hylobates spp., use song in territorial and mate defence (Mitani 1988; Cowlishaw 1992). Male orang-utans, Pongo pygmaeus (Mitani 1985), and howler monkeys, Alouatta spp. (Carpenter 1935), use vocal displays to maintain spacing between groups. Bats are the other group of male terrestrial mammals in which vocal displays have been documented. Male epomophorine bats commonly use vocal displays (Wickler & Seibt 1976); male hammer-headed bats, Hypsignathus monstrosus, call to attract females to a lek (Bradbury 1977a). Male Nyctalus noctula also produce vocalizations that are thought to attract females (Sluiter & van Heerdt 1966). Pipistrellus pipistrellus males advertise the loca- tion of day roosts to females with song-flight displays (Lundberg & Gerell 1986) and use social calls for territorial defence (Barlow & Jones 1997). In the megadermatids, Megaderma lyra produce song-flight displays aimed at females in their groups (Leippert 1994) and Cardioderma cor use song to delineate feeding territories (McWilliam 1987). Complex vocal displays have also been reported in the greater white-lined bat (Bradbury & Emmons 1974; Davidson & Wilkinson 2002). At dawn, males return to defend roost territories and produce complex audible vocalizations consisting mainly of short repeated tones for a period lasting 10e15 min (Bradbury 1977b). Although mating occurs in December or January, males vocalize and defend territories year-round (Bradbury & Emmons 1974; Tannenbaum 1975). Up to eight females can roost within the territory of a male, while other peripheral males Correspondence: G. S. Wilkinson, Department of Biology, University of Maryland, College Park, MD 20742, U.S.A. (email: wilkinso@umd.edu). 883 0003e3472/03/$30.00/0 Ó 2004 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. ANIMAL BEHAVIOUR, 2004, 67, 883e891 doi:10.1016/j.anbehav.2003.06.016