Journal of the Royal Society of Western Australia, 86(3), September 2003 
Figure 2. Rainfall measured on a daily cycle at the Placer Dome Asia Pacific Paddington gold mine, near Ora Banda. Dotted line shows 
the 10 mm level of rainfall. 
Main (1968) reported that N. sutor breeds only in 
February and March, whereas P. occidentalis breeds 
between January and June. Neobatrachus sutor has a 
tadpole life of about 40 days and P. occidentalis has a 
larval development period of 30-40 days (Main 1968). The 
lack of large ponds likely to be present for four to five 
weeks in the undisturbed areas around Ora Banda 
precluded breeding by N. sutor. 
We are convinced that most of the N. sutor that came 
to the surface after the rain on 27-28 January and 2-3 
February did not breed but could have fed on the 
abundance of termites, and possibly other invertebrates. 
Diets of N. sutor and P. occidentalis are unknown; 
however, it is highly likely they eat a variety of 
invertebrates with a high proportion of termites, as Read 
(1999) reported N. centralis eating a wide variety of 
invertebrates but predominantly ants. Predavec & 
Dickman (1993) reported that diets of the arid-adapted 
sympatric N. nichollsi, Cycloram australis and N. centralis 
in south-western Queensland varied but consisted 
mainly of Formicidae, Isoptera and Coleoptera. 
Read (1999) reported that most N. centralis were 
caught on the surface after a minimum of 5 mm of rain. 
Our unpublished terrestrial fauna data for Ora Banda 
from September 2000 to June 2002 indicate that 5 mm of 
rain was insufficient to bring a substantial number of N. 
sutor to the surface (we only caught the occasional frog 
with 5 mm or less rain), but 4-6 mm of rain is sufficient 
for P. occidentalis to be surface active. Pseudophryne 
occidentalis can be found under rocks and leaf litter in 
moist locations when it has not rained for some time. 
They deposit their eggs on damp soil in tunnels and 
tadpoles emerge at an advanced stage of development 
when the tunnels flood with water (Main 1968; Tyler el 
al. 1994). A small amount of rain sufficient to create a few 
surface puddles and a damp environment appears to be 
sufficient for these frogs to become surface active. 
Cocooned and metabolically depressed N. sutor (Withers 
1993, 1995) probably wait for more rain than P. 
occidentalis before they eat their cocoon, dig their way to 
the surface and become active. This species lays its eggs 
in ephemeral ponds during summer. 
If P. occidentalis become surface active after 5 mm of 
rain, then using rainfall data since 1988 we calculate that 
they could have been active on an average of 17.5 
occasions per year (Fig 2). This is an underestimate. 
Rainfall data are recorded for a 24 hour period and if rain 
occurred across a recording period this would have 
increased the number of opportunities for this species to 
be active. Similarly, we do not know if cumulative 
rainfall over a short period that provides a total in excess 
of this amount is also sufficient for this species to become 
surface active. If N. sutor require a minimum of 10 mm of 
rainfall to emerge then they could have been active on a 
minimum average of 9.3 occasions per year, but if they 
require 20 mm of rain this would have reduced the 
number of occasions they could have been active to 3.7 
occasions per year. If N. sutor responds to cumulative 
rainfall over shorter periods then these will also be 
underestimates. Opportunities for N. sutor to successfully 
breed are obviously less than those to feed as they 
require temporary ponds that will last for at least 40 days 
(Main 1968) and to have formed during February and 
March. Because we are unsure of how much rain is 
required to create ponds that will last for at least 40 days 
during summer, we could not estimate the number of 
breeding opportunities over the last 15 years. 
Acknowledgements: Frogs were collected under licence (SF4103) from the 
Department of Conservation and Land Management. This research was 
financially supported by OMG Cawse Nickel and Placer Dome Asia 
Pacific Kalgoorlie West Operations for which we are very appreciative. 
References 
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