feeding strategy of a
Yellow-spotted monitor Varanus
panoptes panoptes (Storr, 1980).
& Photos: Rob Valentic
Monitor Varanus panoptes
a large, predominantly terrestrial monitor, widespread and favouring
heavy soils in humid areas of northern Australia (Wilson &
Knowles, 1992). Indeed, anyone who has witnessed an adult
on its rear legs in the hot expanses of an alluvial floodplain will
testify that it is a formidable sight. The following report
based on a single adult specimen that was followed for several hours
it foraged in and around our makeshift camp in the ‘Top End’ of the
Shady Camp is
located on the banks of the lower Mary River (12°30’E, 131°43’S). A concrete
barrage has been constructed across the river which marks the
confluence of fresh and tidal (estuarine) waters.
Riparian alluvial floodplain with deep cracking in the heavy clay soil.
Open grassland with scattered Banyan Trees Ficus virens in the
campground. Seasonal climate:The
following observation took place on the 17th November 1990.
indigenous people of the Kakadu area refer to this period as
‘Gunumeleng’ on their seasonal calendar. It is the
season of very hot weather with increasing humidity. Clouds
build up each afternoon causing thunderstorms and irregular rainfall.
this period, the herpetofauna becomes increasingly active as air
pressure fluctuates, and typically dormant dry season species such as
Frilled Lizards Chlamydosaurus
kingii leave the tree tops and are seen with more frequency on the ground.
Time: 08:15 to 10:05hrs (Central Standard Time). Weather conditions:
Air temperature: 33°C, with a gentle breeze and full cloud cover.
Relative humidity: 90%+.
An adult male Varanus p. panoptes
(total length estimated at > 1.5 metres) was observed active
the camp. Having camped in the area for several days I was
with the beast, as its retreat site was beneath the concrete foundation
of the toilet only a few metres from camp.
monitor appeared to focus intently on the black-soil substrate
immediately in front of it as it ambled slowly around the gas bottle,
its tongue flickering constantly and its head tilted downwards.
watched and pondered how great it was to have such a guest in camp, the
lizard suddenly stopped, fixing its gaze immediately in front of the
snout. It then began to vigorously scratch the stratum
using the digits of both fore feet as a rake. A small frog
subsequently leapt from the disturbed soil and was seized in the jaws
of the monitor, whilst in mid-flight, and was consumed with the head
raised at an acute angle. The
monitor progressed again and continued this foraging pattern within an
area of some sixty square metres before retiring beneath the ‘bush
dunny’ at 10:10hrs. During these observations, a distance
of some two metres was maintained between myself and the lizard,
which did not seem at all perturbed by my close proximity. A
total of eighteen frogs were consumed in the above manner.
monitor discovered a further specimen which I stole from him for
identification purposes. It was identified as an Ornate
Frog Opisthodon ornatus, a
species also widespread across the northern half of the
continent. From close scrutiny it appeared that all other
taken by the monitor were of the same species.
bipedally erect adult Yellow-spotted Monitor Varanus p. panoptes
from north of Longreach, Queensland
Burrowing Frog Opisthodon ornatusfrom
close inspection of the immediate stratum was made whenever the monitor
stopped, but no discernible evidence of any imperfection in soil level
or consistency could be detected. Perhaps the vision of V. p. panoptes
was considerably more adept at noting such indications (if any) than
mine. Perhaps scent particles from the concealed frogs were
transferred via the constantly flickering tongue-tips. In
any case, the success
was exemplary, as on any occasion the monitor would stop and commence
scratching, he did not fail to locate and devour another O. ornatus.
REFERENCE: Wilson, S.K.
& Knowles, D.G. 1992. Australia's Reptiles
- A Photographic Reference to the Terrestrial Reptiles of Australia. Cornstalk Publishing,
Pymble NSW. 447pp.