Journal of the Royal Society of Western Australia, 87(3), September 2004 
considerable amount of field work on all species in this 
genus (Roberts 1997a,b). 
Data are presented as means ± standard errors with 
an a of 0.05 used throughout. 
Results 
Field Observations 
Kellerberrin: on the 16 th April 2002, there was a heavy 
rainfall event that produced 13.5 mm of rainfall in 24 
hours. Subsequently, we observed a large breeding 
chorus where males were calling both in the water and 
from the damp ground surrounding the pond. From 
19:00 to 19:30 h, we observed four single-male matings. 
From 20:00 - 21:00 hrs, we observed three separate, 
multiple-male amplexus events comprising five, six and 
seven males respectively, trying to amplex a single 
female. In each multiple-male amplexus, one male was in 
inguinal amplexus, one male around each of the front 
legs, and the remaining males were vying for position 
underneath and alongside the other males (Figure 1). On 
the following night (17 th April), after a further 7 mm of 
rain, during two hours of observation, we saw two single 
male matings. On the third night (18 ,h April), we 
observed three single male matings. By the fourth night 
(19 th April) all breeding activity (calling and mating) had 
ceased and the pond contained numerous egg masses. 
There was a strong bias to males on 16 th April but this 
was drastically reduced on the following two nights 
(Table 1). 
Narembeen: this pond was observed from 00:30 hrs to 
03:30 hrs. At 00:30 hrs there was one amplexed pair. 
Other pairs formed over the next three hours. Seventeen 
pairs, four unamplexed females and eighteen 
unamplexed males were collected between 03:00 hrs and 
03:30 hrs (close to dawn: a total of 21 females, 35 males). 
Sixteen conventional single male, single female pairs 
formed. A seventeenth pair was approached and touched 
by a calling male but the calling male did not make any 
obvious attempt to amplex or displace the amplexed 
male. The caller left and resumed calling. 
At Narembeen, mated males had significantly smaller 
snout-vent lengths than unmated males (t n = 2.203, p = 
0.035; mated males 59.23 mm ± 1.01; unmated males, 
62.22 mm ± 0.91). The correlation between snout-vent 
lengths of mated males and females was not significant (r 
= 0.150, p > 0.05). The number of eggs deposited per pair 
averaged 918 ±102 with a range from 28 to 1616. We do 
Figure 1. Amplexed group: one female and four males, 
Kellerberrin. The head and limbs of the female are obscured but 
her abdomen is visible between the two males on the left. 
not know whether females were depositing eggs before 
pairs were collected so the average may be an 
underestimate of actual fecundity if there were some 
incomplete clutches (e.g., the low of 28). 
Operational Sex Ratios 
Operational sex ratios and frequencies of multiple 
male matings are given in Table 1. For the first night at 
Kellerberrin we calculated separate OSR values for 
observations from 19.00 - 19.30, and those made between 
20:00 hrs - 21:00 hrs, because females were not marked 
and we could not determine whether the same females 
were amplexed at both time periods. To calculate the 
OSR we assumed all frogs present in the pond at the 
time of observation were available to mate as all females 
appeared gravid and most males were calling. 
Discussion 
Our observations document polyandrous mating 
aggregations that might lead to multiple paternity of 
single egg clutches in N. kunapalari. Our data are 
consistent with an increased frequency of multiple-male, 
single females aggregations when the OSR is more 
heavily male biased If we assume the early data from 16 th 
April reflect initial pairing that is modified over time 
(Table 1). Our observations are comparable to the 
multiple-male amplexes in N. pelabatoides, illustrated on 
the cover of Main (1965). We did not follow amplexed 
pairs through the process of egg deposition and the extra 
Table 1 
Sex ratio and frequency of single- and multiple-male matings in breeding choruses of N. kunapalari. 
Kellerberrin Narembeen 
16/4/2002 17/4/2002 18/4/2002 21/2/1986 
19.00-19.30 20.00-21.00 
Males 
32 
32 
28 
26 
35 
Females 
4 
4 
15 
14 
21 
OSR 
0.125 
0.125 
0.54 
0.54 
0.6 
Number single matings 
4 
0 
2 
3 
17 
Matings with > 1 male 
0 
3 
0 
0 
0 
% Matings with > 1 male 
0 
100 
0 
0 
0 
98 
