"Behavioural Observations on an Unnamed Species of Skink Liopholis (formerly Egernia) ""Cape Range"" from Cape Range"

2012·1.8 MB·English

by  M J Bamford

BEHAVIOURAL OBSERVATIONS ON AN UNNAMED
SPECIES OF SKINK LIOPHOLIS (FORMERLY EQERNIAJ
“CAPE RANGE” FROM CAPE RANGE
By M.J. BAMFORD and A.R. BAMFORD
23 Plover Way, Kingsley, WA, 6026.
INTRODUCTION on the North West Cape (ca.
22°30'S, 113°45'E). The collection
Social behaviour, in which
was carried out as part of an
individuals of a species form a
inventory fauna survey being
cohesive group and interact with
conducted for the Department
each other over extended
of Defence under a Licence to
periods, is rare among reptiles.
Collect Fauna for Scientific
Among Australian skink lizards
Purposes, and in 2009/2010 the
until recently assigned to the
specimens were maintained in
genus Egernia, however, such
captivity under SF006843, issued
social behaviour is commonplace
by the Department of Environ¬
and well-documented (Hutch¬
ment and Conservation.
inson 1993). In many species, the
social unit is a family group Six specimens were caught from
consisting of adults and young two locations in pitfall and
funnel traps set along drift-
animals of one or more age
fences in open shrubland and
cohorts, but the nature of
hummock (spinifex) grassland on
interactions within such units is
not well-known. From late 2004, shallow red sand over limestone.
the opportunity arose to observe The six specimens were kept
because they were initially
social behaviour in a captive
breeding colony of what was thought to represent a major
then an undescribed species range extension for E. inornata,
and two of these were lodged
similar to Egernia inornata, and
this paper presents the results of with the WA Museum. The
these observations. In a revision remaining four specimens, three
from one location and one from
of Egernia, E. inornata has been
a different location, were kept
placed in the genus Liopholis
under observation when it was
(Gardner et al. 2008), and the
noted that a female was pregnant
undescribed species is referred to
here as Liopholis “Cape Range”. (members of the group are
viviparous).
ORIGIN OF STUDY ANIMALS
CAPTIVE HOUSING
The study animals were collected
in October 2004 on the The captive specimens were
Learmonth Air Weapons Range initially maintained in a 60cm
107
vivarium on red sand taken from females) at the time of collection
their collection location. The and three or more years old. They
colony was moved to a 90cm displayed no growth in captivity:
vivarium in April 2009. They the male (lizard #1) had a SVL of
had continuous access to a “hot- 62mm in October 2004 and in
rock”, a shelter that simulated a February 2010. The two females
burrow (two shelters provided (lizard #2 and #3) had SVLs of 56
from April 2009), water ad and 57mm in October 2004 and
libitum, and were fed several February 2010.
times a week on commercial cat
From 2005 to July 2011, breeding
food (chicken), finely chopped
occurred in January of 2005,
apple and live food (termites,
2008, 2009, 2010 and 2011. Mating
small crickets and small wood and courtship behaviour were
roaches). The vivarium was lit
never observed. Breeding events
with a “repti-glow” light for
were as follows:
approximately 10 hours a day.
January 2005. Wild-caught
Heating and lighting were not
female (lizard #2), probably
varied over the year, but the
pregnant when collected, pro¬
artificial period of lighting was
duced two young. One of these
shorter than the summer
found dead in July. Second
daylength, so the lizards did
specimen (lizard #5) survived and
experience seasonal variation in
still alive in March 2011.
photoperiod. They also experi¬
Gestation was approximately 10
enced seasonal variation in
to 12 weeks.
ambient temperature, with this
varying from 22° to 30° C in 16th January 2008. Lizard #5
summer and 16° to 20° C in produced two young when just
winter. under three years of age.
Therefore, sexual maturity in
third year of life. She had an SVL
DESCRIPTIONS OF CAPTIVE of 56mm and has displayed little
SPECIMENS AND BREEDING subsequent growth. When
measured at the age of 15 months
Three specimens, collected on 8th
(April 2009), these two young
to 10th October 2004, were still
had SVLs of 41mm and 44mm.
alive in March 2010. The fourth
specimen died in April 2005 4th and 14th January 2009. Lizard
from injuries received during #5 produced two young; her
fighting. It is believed this second brood. When measured at
specimen (a male) was from a the age of three months, these
different colony and was not young had SVLs of 30 and 36mm.
accepted by the other animals. At the age of 13 months, the
Based on subsequent obser¬ larger of these had an SVL of
vations on captive-bred animals, 47mm.
the three surviving specimens 12th January 2010. Lizard #5
were adults (one male, two produced one young, although it
108
is suspected that a second young but did not breed again. Her
was born and eaten. At this time captive-bred daughter bred for
there were four adults and four the first time at the end of her
juveniles (one or two years old) third year, and bred each year
in the colony. The colony was subsequently, bearing either one
subsequently divided into or two young on each occasion.
separate vivaria, with Lizard #1 The father is lizard #1, the
(wild caught male), lizard #2 surviving wild-caught male.
(wild caught female) and lizard
Measurements indicate that
#5 (captive born female) in one adult males are slightly larger
enclosure, and Lizard #4 (wild
than females. They are also
caught male) and the surviving
slightly brighter in colour.
young of lizard #5 in the other Young animals are also brighter
enclosure.
in colour than adults, being
3rd January 2011. Lizard #5 pro¬ orange with a distinctly dark cap,
duced one young. compared with the tawny and
In summary, the wild-caught more uniformly-coloured adults
female, pregnant at the time of (see Figure 1). This distinctive
collection, produced two young juvenile colouration fades by the
Figure 1. Juvenile Liopholis sp. "Cape Range" raising its forequarters in an agonistic
display towards an approaching adult.
109
age of one year. Little or no Adults appeared less inclined to
growth occurs after sexual steal food from juveniles less
maturity is reached (at the end of than one year old than from
the third year of life for one other adults.
female). The three wild caught
Interactions between adults and
animals were adult-sized when
juveniles were more complex
collected so were presumably at than interactions observed be¬
least three years old. They there¬
tween adults and included clear
fore had a minimum age of 11
agonistic behaviour. Juveniles in
years by July 2011 and showed no
their first year of life and still
signs of senescence.
displaying the contrasting bright
orange body and dark cap
employed posturing when ap¬
OBSERVATIONS ON SOCIAL
proached by an adult, including
INTERACTIONS
when food was present. This
Social interactions between involved raising and laterally
adults were limited. Lizard #4 compressing the body, particu¬
died from injuries sustained in larly the fore-quarters, arching
the neck and tilting the head to
fights with lizard #1. This death
was almost certainly due to display the dark cap towards the
inadvertently mixing animals approaching adult (see Figure 1).
from different colonies. No other This appeared to appease the
fighting was observed but some adult, which would otherwise be
injuries were sustained amongst quite capable of stealing the food
the captive animals, consisting of or even eating a young juvenile,
scars across the back and the loss although the young juveniles
(followed by regeneration) of the would also sometimes run away.
tail in some cases. One animal The possible disappearance and
also lost a digit. This suggests that presumed death and consump¬
occasional fights did take place, tion of one neonate in January
although some injuries, such as 2010 suggests that the appease¬
the loss of a tail-tip, could have ment display was not always
been inadvertent when the successful, although this may
animals were being fed. At least have been an artefact of captive
one of the wild-caught adults conditions and excessive colony
had a missing digit. When feed¬ size. Juveniles over a year old and
ing, particularly on live food, in which the distinctive
adults would try to steal food colouration had faded did oc¬
from each other and would run casionally attempt the posturing
away with food to avoid con¬ display when approached by an
frontations. On one occasion, adult, but also ran away.
lizard #5 (adult female) trembled Posturing was not observed in
when approached by lizard #1 juveniles over two years of age.
(adult male). This was in Feb¬ In addition to the agonistic dis¬
ruary 2010 so was post-breeding. play, juveniles in their first year
110
of life would approach feeding reptiles even in largely solitary
adults and appeared to taste the species, but the juvenile Liopholis
food they were eating. While “Cape Range” are not simply
juveniles recognised live insects brighter, but also have a dis¬
as food readily, they did not tinctly dark cap that is presented
immediately recognise cat-food to adults as part of the agonistic
or finely-chopped apple as edible. display, it is not known if such
By licking the food being eaten colouration and displays are
by an adult, they appeared to found in other Liopholis species,
“learn” that this material was or in other social species formerly
edible. This licking of food held assigned to Egernia.
by an adult did not involve theft
The loss of the early-juvenile
of the food by the juvenile, and colouration and behaviour
the adult did not try to avoid the
results in immature lizards (more
contact as it would do if
than about a year old and
approached by another adult. certainly more than two years
The agonistic display was not
old) having to run from adults
used by juveniles approaching
more often, and it may be at this
adults, only by juveniles when stage that young lizards may
approached by an adult.
move to the periphery of a
colony and even disperse. Sexual
maturity is reached in the third
CONCLUSIONS year of life and at least in
captivity longevity is in excess of
The social skink Liopholis “Cape
11 years.
Range” has distinctive early-
juvenile colouration and be¬
haviour that ensures young REFERENCES
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adults without themselves being
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