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Account of a Greater Bar-sided Skink Eulamprus tenuis trapped in a narrow crevice opening

  • Department of Planning and Environment
Herpetofauna 42 (1 & 2) 2012 Page 11
The Greater Bar-sided Skink Eulamprus tenuis
(Figure 1) is a common insectivorous lizard
that occurs in Sydney. The species is saxi-
colous and arboreal, found in woodland and
forested areas on the east coast of Australia
(Greer, 2002; Rankin, 1973). The Bar-sided
Skink is not frequently seen because of its cre-
puscular habits and preference for shade.
Basking often occurs close to retreat sites such
as rock crevices, hollow logs and cracks in
trees (Swan et al., 2004).
On 8 July 2012, while bushwalking in
Georges River National Park (33.97°S
151.01°E), south of Sydney, I observed a Bar-
sided Skink becoming wedged at the head
and neck region in a narrow part of a sand-
stone crevice (Figure 2). The incident occurred
in dry sclerophyll forest on a steep hillside
dominated by sandstone structures. The
crevice was of relatively even width at first
glance; however upon re-examination post-
incident, the roof possessed rough protruding
grains of sandstone, most likely from erosion.
The trapped lizard was an adult, approxi-
mately 6 cm SVL.
I observed the lizard basking next to the
crevice before trying to retreat, presumably
disturbed by my approach. The head and
neck became firmly lodged between the roof
and base of the crevice as the lizard pressed
Matthew Mo
Department of Primary Industries, PO Box 242, Parramatta, NSW 2151.
Figure 1. A Greater Bar-sided Skink Eulamprus tenuis.
itself into the resulting position, rotating the
head from side to side to penetrate further.
The body and tail was left completely exposed
(Figure 3). I touched the lizard around the
hind limbs to determine that the lizard was
actually caught, as opposed to choosing to
remain stationary. The time of the incident
was 15:56 hours, referenced from a digital
image recording. At the time, there seemed a
possibility that the lizard was tensing up parts
of the neck against the crevice roof in a
defensive response of my presence; hence the
lizard would relax its body upon my departure
and escape by its own means. Initially I chose
not to engage in action that may constitute
I returned at 16:33 hours (more than half an
hour later) and found the lizard in the identi-
cal position. Presuming that the lizard was
highly unlikely to free itself and would certain-
ly succumb to inevitable predation or starva-
tion otherwise, I aided its release. I gradually
slid a fresh eucalypt leaf over the lizard, util-
ising temporary gaps between the lizard and
the crevice roof created as the lizard rotated
tension around different parts of its neck
region. The leaf was wedged to shield the
lizard's head and neck from the rough texture
of the crevice roof. I grasped the lizard by the
body and applied gentle tension away from
the rock structure, freeing the lizard with rela-
tive ease.
The lizard, placed on a part of the sandstone
structure where I initially observed it, showed
obvious signs of weariness, i.e. heavy breath-
ing. Apart from minor scratches to the scales
on the head, no serious injuries were sus-
tained (Figure 4). The lizard returned to its
crevice without difficulty after a short recovery.
Under torchlight, I observed another Greater
Page 12 Herpetofauna 42 (1 & 2) 2012
Figure 2. Head and neck of lizard firmly lodged between the roof and
base of the crevice.
Herpetofauna 42 (1 & 2) 2012 Page 13
Figure 3. The lizard in a vulnerable position with the body and tail com-
pletely exposed.
Bar-sided Skink and a Broad-tailed Gecko
Phyllurus platurus deeper in the same crevice.
From this, I gather that the particular crevice
is commonly used by saxicolous lizards.
Although the incident occurred when the
lizard attempted to retreat in response to my
approach, I consider the action of it becom-
ing caught between the roof and floor of the
crevice a natural occurrence. The same situa-
tion may have occurred if a predator such as
a carnivorous bird or monitor lizard had been
the cause of the disturbance. The incident
described here raises questions as to the fre-
quency and/or likelihood of saxicolous lizards
becoming trapped in their natural retreat
sites. In the past, it would be presumed that
saxicolous taxa move fluidly in their natural
surroundings and would probably never
become trapped in a position as described
here. This observation is an example of a
saxicolous species misjudging the size of a
crevice opening and taking up a position that
could result in death.
Although scale loss did not occur in this inci-
dent, scincid lizards can be quite resilient
towards open abrasions. In the past, I have
observed free-living White's Skinks Liopholis
whitii and Eastern Blue-tongued Skinks
Tiliqua scincoides persisting in the wild
despite missing scales. In addition, head
wounds are frequently sustained in male
Broad-headed Skinks Eumeces laticeps
during intraspecific fighting (Cooper & Vitt,
I thank Dr Brad Law for reviewing the original
manuscript and providing useful comments.
Page 14 Herpetofauna 42 (1 & 2) 2012
Cooper, W.E. & Vitt, L.J. 1987. Deferred
agonistic behavior in a long-lived scincid
lizard Eumeces laticeps. Oecologica 72: 321-
Greer, A.E. 1992. Revision of the species
previously associated with the Australian
scincid lizard Eulamprus tenuis. Records of the
Australian Museum 44: 7-19.
Rankin, P.R. 1973. The barred sided skink
Sphenomorphus tenuis tenuis (Gray) in the
Sydney region. Herpetofauna 6(2): 8-14.
Swan, G., Shea, G. & Sadlier, R. 2004. A
Field Guide to Reptiles of New South Wales.
Second Edition. Reed New Holland, Sydney.
Figure 4. Minor scratching on the head post-incident.
... A major feature is Yeramba Lagoon, the location of the first established population of invasive Red-eared Sliders (Trachemys scripta elegans) in New South Wales (Burgin 2006;Robey et al. 2011). This is also where we once observed a Greater Bar-sided Skink (Concinnia tenuis) retreating and becoming stuck in a narrow crevice opening in the rocky outcrops overlooking the Georges River (Mo 2012). On this visit, this species was numerous, and one individual fled, potentially due to the presence of a Brown Goshawk (Falco cenchroides) perched in a tree close to the park boundary ( Fig. 19). ...
A laboratory experiment with the broad-headed skink (Eumeces laticeps) involving staged agonistic encounters demonstrates that larger males have an advantage over smaller ones in agonistic bouts. Field data on head wounds produced by intraspecific fighting during the breeding season show a much higher frequency of new wounds among males over 100 mm in snout-vent-length than in smaller males. The significant difference in new-wound frequency strongly suggests avoidance of fights by the small males, which is corroborated by laboratory and field observations. Access by males to reproductively active females depends on the ability to defeat other males in aggressive contests virtually always involving head biting if the males are of nearly equal size. Because the probability of winning agonistic encounters increases with size, young males avoid fights with older males. Aggressive contests with larger males and reproductive attempts other than courtship in the absence of larger males are deferred. Aggressive behavior in E. laticeps may be employed in direct defense of females, but might also be expressed in defense of specific sites and/or territories. In the laboratory, males in their home cages were significantly more likely to win encounters with males of similar size than were males fighting in the home cages of opponents. This suggests that encounter site could be important in determining encounter outcome and that field study of possible site defense or territoriality is needed.
A Field Guide to Reptiles of New South Wales
  • G Swan
  • G Shea
  • R Sadlier
Swan, G., Shea, G. & Sadlier, R. 2004. A Field Guide to Reptiles of New South Wales. Second Edition. Reed New Holland, Sydney.
The barred sided skink Sphenomorphus tenuis tenuis (Gray) in the Sydney region
  • P R Rankin
Rankin, P.R. 1973. The barred sided skink Sphenomorphus tenuis tenuis (Gray) in the Sydney region. Herpetofauna 6(2): 8-14.