Smith & Roberts: Call repertoire of Litoria adelaidensis 
correlation for Rana nicobariensis between duration of its 
advertisement call and proximity of its nearest calling 
neighbour (Jehle & Arak 1998). Litoria adelaidensis males 
often call from emergent vegetation (typically reeds), and 
accordingly the physical structure of their breeding 
habitat may impose a limitation to male spacing. These 
circumstances may favour graded interactions between 
males. 
Call type 4 was rarely recorded and may function in 
male-male interactions. On other occasions, we have 
observed pairs of males in close proximity, on a single 
reed stem, making this call. However, the locations of 
other males when call type 4 was recorded in this study 
are unknown. These observations, and the rarity of call 
type 4, indicate that it may act as a short range 
"encounter" call (e.g. Robertson 1984; Halliday & Tejedo 
1995). This conclusion needs confirmation by further 
observation and playback experimentation. 
Studies designed to further investigate the functions 
of the call types of L. adelaidensis are required. These need 
to examine responses of both males and females to call 
playback, and account for how the intensity of the calls 
of neighbours and male size may affect calling tactics 
(e.g. Robertson 1984; Rose & Brenowitz 1997; Brenowitz 
& Rose 1999). The slender treefrog may lend itself to 
studies concerned with the evolution of vocal repertoires 
and vocal behaviours in frogs. 
Acknowledgements: This research was conducted with the permission of 
the Department of Conservation and Land Management (permit 
SF002650), Western Australia, and the University of Western Australia, 
Animal Experimentation Committee (approval number 98/008/E36). 
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