Journal of the Royal Society of Western Australia, 86:91-95, 2003 
Call repertoire of an Australian treefrog, 
Litoria adelaidensis (Anura, Hylidae) 
M J Smith & J D Roberts 
School of Animal Biology M092, University of Western Australia, 
35 Stirling Highway, Crawley WA 6009 
£3 droberts@cyllene.uwa.edu.au 
(Manuscript received November 2002 ; accepted April 2003) 
Abstract 
Litoria adelaidensis (Anura: Hylidae) has a call repertoire that includes two structurally different 
call types. Males produced three recognizable pulsed calls (call types 1 to 3) and one unpulsed call 
(call type 4). All call types have two distinct frequency peaks. Call type 1 was produced most often, 
suggesting that this signal functions to attract females. Call type 4 was rarely produced and may be 
associated with male-male interactions, as males in close proximity to each other were observed 
making this call. The purposes of call types 2 and 3 are unknown. The different calls may be part of 
a graded response incorporating both male-male interaction and female attraction. 
Key words: frog, vocal repertoire, advertisement call, acoustic communication, Hylidae, Litoria 
adelaidensis 
Introduction 
Organisms that emit acoustic signals often have a 
repertoire of calls, the extent of which reflects the 
strength and complexity of both sexual and natural 
selection (Narins et al. 2000). Female frogs typically use 
the male call to locate and choose between potential 
mates and may therefore impose strong selection on call 
structure (Gerhardt 1994). Male frogs can use acoustic 
signals in response to physical and/or acoustic intrusions 
by other males (Narins et al. 2000) and may use 
conspecific calls to determine the proximity (Brenowitz et 
al. 1984), size (Davies & Halliday 1978; Wagner 1992) and 
possibly condition of rivals (Halliday & Tejedo, 1995). 
Although many species use a single call for both 
functions ( e.g . Littlejohn 1977; Wells 1977; Halliday & 
Tejedo 1995), a number have developed more complex 
signal repertoires (e.g. Given 1987; Narins et al. 2000) in 
which different calls serve different functions (e.g. 
Robertson 1984; Littlejohn & Harrison 1985). 
Male frogs can produce acoustic signals that differ in 
both temporal and spectral structure (e.g. Ovaska & 
Calbeck 1997; Jehle & Arak 1998). Hyla regilla provides an 
excellent example, as it produces three distinct signals 
with similar spectral characteristics but different 
temporal properties (Brenowitz et al. 2001). A diphasic 
"advertisement call" is emitted commonly throughout 
the night and appears to attract females and to influence 
male spacing (Whitney & Krebs 1975a,b). A monophasic 
"advertisement call" is emitted at a high rate when 
females approach and is produced until the male has 
entered into amplexus with the female, but its exact 
function remains unclear (Brenowitz et al. 2001). Hyla 
regilla also produce an "encounter call" that is believed to 
be an aggressive signal that is important in the 
establishment of spacing between calling males 
© Royal Society of Western Australia 2003 
(Brenowitz et al. 2001). Males will switch to the encounter 
call after hearing the signal of an "intruding male". 
Not only do male frogs often produce several different 
signals, but the signals may vary in a graded fashion 
from one extreme to another or from one call to another 
(Gerhardt & Huber 2002). Graded signals are typically 
produced in response to external stimuli such as 
conspecific male calls and/or physical intrusions or the 
approach of a potential mate. The advertisement call of 
Rana nicobariensis, for example, varies considerably in 
duration (approximately 20 fold) and the duration of the 
call is inversely related to the distance between the focal 
calling male and his nearest calling neighbour (Jehle & 
Arak 1998). Further, some species produce compound 
calls that incorporate both advertisement and aggressive 
signals (cf Jehle & Arak 1998). Accordingly, the degree of 
within and between species variation in the acoustic 
signals of frogs contrasts with the view of early 
researchers that the calls of anurans were highly 
stereotyped and discrete (e.g. Blair 1958; Bogert 1960). The 
acoustic signals made by frogs show great variability 
which can be generated by natural, inter-sexual and 
intra-sexual selection (Gerhardt & Huber 2002). 
A first step in studying anuran vocalizations is to 
record and quantify the types of calls that are produced 
by a species and to associate them with possible 
functions. Although there are extensive data on calls of 
Australian myobatrachid frogs (e.g. Littlejohn 1959; 
Littlejohn & Main 1959; Roberts & Wardell-Johnson 1995; 
Roberts 1997) and investigations of their function (e.g. 
Robertson 1984; Littlejohn & Harrison 1985; Gerhardt et 
al. 2000), comparatively few studies have investigated the 
call structure or call function for Australian hylid species. 
Here we quantify the acoustic signals of a south-western 
Australian frog, the slender treefrog, Litoria adelaidensis. 
The vocal repertoire of this species has not been 
described, but anecdotal evidence suggests that L. 
adelaidensis emits several different calls. 
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