I

February 1992

Asiatic Herpetological Research

Vol.4, pp. 99-112|

On the Ecology of Przewalsky's Gecko (Teratoscincus przewalskii) in theTransaltai Gobi, Mongolia

DIMITRI V. SEMENOVx

1

AND LEO J. BORKIN 2

Severtzov Institute of Evolutionary Animal Morphology and Ecology, Russian Academy of Sciences,

Moscow 117071, Russia
department ofHerpetology, Zoological Institute, Russian Academy of Sciences, St. Petersburg 199034,
RussiaAbstract. -Przewalsky's Gecko {Teratoscincus przewalskii) is one of the least studied representatives of
the herpetofauna of Central Asia.

We present the results of a study of the habitat, demography, spatial

distribution, activity, and diet of this lizard.

Our observations indicate that individuals of T. przewalskii are
Individuals of this species do not

active foragers that feed primarily on beetles, and are strictly nocturnal.
protect territories, but do exhibit aggressive behavior.

We present a detailed analysis of home ranges over a

five year period.

Key words: Reptilia, Lacertilia, Gekkonidae, Teratoscincus przewalskii, Gobi Desert, Mongolia, ecology.

FIG.

1.

An adult Teratoscincus przewalskii.
Introduction

FIG. 2.

A juvenile Teratoscincus przewalskii.

Zhao, 1985).

From the time it was first described,
Przewalsky's Gecko (Teratoscincus

summers of 1981, 1982, andobservationsof this species were
1985,

przewalskii Strauch, 1887) has remained
one of the least studied representatives of
the herpetofauna of Central Asia.
As
from
its
close
CentralAsian
distinguishedrelative, the Turkestan Plate-Tailed Gecko(T. scincus Schlegel), this species has been

performed at the Ekhiyn-Gol (Ehiin-Gol)
Desert Station of the Joint Soviet-

very rarely studied in nature, and it was

Ekhiyn-Gol (Ehiin-Gol) Oasis is situated in
the subzone of extremely arid deserts(average annual precipitation is 20-50 mm)

1961 that it was recorded in theonly
fauna of Mongolia (Figs. 1, 2 and Plate 1).
Occasional data on its biology are available(Borkin et al., 1983a, 1983b; Munkhbayar,
1976; Obst, 1962; Semenov and Borkin,
1986; Szczerbak and Golubev, 1986;in

1992 by Asiatic Herpetological Research

In theMongolian Complex Biological Expedition.
In addition, material on this species wascollected in other regions of the Transaltai

Gobi in the course of faunal surveys. The

in the south of the

Bayanhongor Aymag

Frosty winters withas
low as -34°C, hotof
temperaturessummers (air temperatures of up to 42°C
(Province), (Fig.

air

3).

Vol. 4, p. 100

Asiatic Herpetological Research

February 1992

Asiatic Herpetological Research

February 1992

Vol. 4, p. 101

U
u
3
«
L.
O.

E
<u

H

14

18

20

22

Time (hrs)FIG. 4. Daily variation in air and ground surface temperature at Ekhiya-Gol Oasis, Transaltai Desert,
Bayanhongor Aymag (Province), Mongolia, June 15, 1981, warmest day of the Summer.

sandy

site

with some Saxaul.

stakes were placed at 10

Markedm intervals. The

plot was inspected daily at various times

from June 26 to August 17, 1981, from
July 5 to August 13, 1982, and July 7-8,
1985. Gecko observations were recorded
in relation to the stakes. In 1981 and 1982,
a total of 83 geckos were marked, and 365
recaptures were recorded on the plot andnear its boundaries. In fact, all individuals
inhabiting the plot during this period weremarked.

Occasional non-marked animals

appeared due to irregular invasions. The
data were processed according to Semenov
and Kulikova (1983) and Semenov andBorkin (1985). For each individual, thesize of the home range, average andmaximum movement, average radius ofsightings, extent of reciprocal overlapping,in range position wereand changes

determined depending on the completenessof the data. Body length, tail length, andsex of captured animals were also recorded.
Along with observations on this permanentplot, the population density of this speciesinEkhiyn-Gol was determined by acomplete removal study on August 16-23,

1981 on another plot of the same size,
located on the other sand site. The absolutedensity with consideration of the marginal
effect was estimated according to Semenov

and Shenbrot (1985).

To characterize the daily and temperaturedependent activities of Przewalsky's
Gecko, the time of observation and air andground temperatures were recorded.
Cloacal temperatures were recorded from45 geckos in three localities.

The stomach contents of 29 individuals
caught in the vicinity of the Ekhiyn-Gol
Oasis were studied. The weight of thestomach and its contents and the taxonomic
identity, size, and dimensions of food items
were determined, and the parameters of dietdiversity were calculated according toSemenov (1986).
The behavior of geckos in their naturalenvironment was observed in a corral 2 by
2 m, by 25 cm in height, constructed ofObservations werepolyethylene film.
andnight with a red torch.
performed dayAsiatic Herpetological ResearchVol. 4, p. 102

February 1992

969
Relative Humidity

Barometric Pressure

-968

£

'i

3

X

>

0!

24

I

i

i

i

i

i

i

i

i

i

i

2

4

6

8

10

12

14

16

18

20

962
22

24

Time
FIG. 5.

Daily variation in relative humidity and barometric pressure at Ekhiya-Gol Oasis, Transaltai
Desert, Bayanhongor Aymag (Province), Mongolia, June 15, 1981, warmest day of the Summer.

Results and Discussion

addition to Saxaul on sand, and sometimes

Habitat Preference

replace it. On margins of oases, geckos
occur on small sandy hills with low shrubs

Unlike the stenotopic psammophilous T.
scincus (Szczerbak and Golubev, 1986),
Przewalsky's Gecko (also a predominantly

psammophilous species) regularly occurs inother biotopes. It seems to depend on therelative rarity and patchiness of sandy sites
in the Transaltai Gobi where broken stonedeserts prevail. The commonest habitat ofprzewalskii in this region issemistabilized sands overgrown with
Saxaul (Fig. 6). Stationary observations
are performed at precisely such a place.
The marking plot in 1981 was permanently
inhabited by 18 individuals. A similar
result was obtained on the other census plot
where 19 geckos were caught.
With
consideration of the marginal effect, the last
figure yields an estimated density of 11.5
individuals per hectare.
In 1982, 12
residents
were recorded on thepermanent
T.

plot.

In gecko habitats, Tamarix sp. andCalligonum mongolicum may be present in{Reaumuria soongorica, Zygophyllum
xanthoxylon, Ephedra przewalskii, andrarely, Nitraria sphaerocarpa). It should be
noted that Przewalsky's gecko was foundin only part of all seemingly suitable sandy

biotopes (habitats) in the Transaltai Gobi.
They definitely avoid clear nonstabilized
sand without vegetation.

Sometimes geckos also settle on small
with fine soil covered by a dense

hills

surface crust, or on takyr-like sites, such asat Toli-Bulag in the vicinity of Ekhiyn-Gol

or at Dzamiin-Huren-Els [southernmost

Mongolia, Omnogovi Aymag (Province)].

At the latter site, geckos were numerous
under Tamarix sp. bushes and under
Nitraria sphaerocarpa. Thus, on August
31, 1982, in spite of rain, 22 individuals
were caught in a 1.5 hour period.

As well as on sandy biotopes, thisspecies may be found on broken stonedesert sites adjacent to sand, includinghammada absolutely devoid of vegetation.

Asiatic Herpetological Research

February 1992

FIG. 6.

A small sand hill with Saxaul Trees {Haloxylon ammodendron).

Vol. 4, p. 103

This was a plot used forobservation of T. przewalskii, June 22, 1981.

According to our data, T. przewalskii
may live in areas up to 200 m distant fromsand. Obviously, this enables geckos topopulate isolated sandy areas scattered in

51 mm.

the Transaltai as islands in stony regions ofOn the plot in 1981, 16 males, 11
females, 22 subadults, and 15 juveniles
were marked. On the same plot in 1982,
13 males (12 marked the previous year), 8
females (6 marked the previous year), 15
subadults (7 marked the previous year),and 3 juveniles were recorded. Of the 12

thedesert.

We

note asituation inparticularly

Bayan-Gol[Omnogovi Aymag (Province)] where ininteresting

the middle of July, geckos were found only

on slopes (sometimes steep) of stony hills,
and were completely absent from adjacentsands (Semenov and Shenbrot, 1986b).
Demographic Parameters
In the Ekhiyn-Gol population, adults
with body lengths exceeding 70
areprevalent. The maximum body length of ammmature gecko is 94 mm for males, and
96 mm for females. Body weight reaches
25 g.
The minimum body length ofindividuals that have overwintered once isAfter hatching, juveniles have aminimum body length of 40 mm and abody weight of about 2 g (Fig. 7).

geckos caught on the plot in 1985, 6 weremarked in 1981-1982, including a male anda female marked as adults in 1981, a female
marked as an adult in 1982, a male marked
as a subadult in 1981, and a male and afemale marked as subadults in 1982.
All subadults marked in 1981 reached
the adult sizeby the summer of 1982,

though some of them were provisionallyleft in thesubadult group.

Thus, maturity

Vol. 4, p. 104

Asiatic Herpetological Research

February 1992

February 1992

TABLE. 1.

Vol. 4, p. 105

Spatial distribution in a population of T. przewalskii.

Sex/age groups, yearof observations

Males (1981)

N

Asiatic Herpetological ResearchHome range area,

Average movement,

Radius of recurrentm"msightings, m

Maximalmovement, mAsiatic Herpetological ResearchVol. 4, p. 106

February 1992

FIG 8. The movements of an adult female T. przewalskii.

Dot: records of the lizard in 1981. Triangle:
records of the lizard in 1982. Star: centroid of the 1981 records. Hexagon: centroid of the 1982 records.
Solid arrow: denotes the next closest sighting in time. Dashed line: arbitrary boundary of the 1981
individual range. Dot-dash line: arbitrary boundary of the 1982 individual range.

other parameters (the combined data forboth seasons) are higher in males than infemales (Table 1), but in no case is thedifference at a significant level (home= 0.61,> 0.05;tmethods (Stamps, 1977).

N =19, P > 0.05;
individual movements: t = 1.92, N = 32, P

range:

conditions of relatively poor visibility, andwidely exploiting nonvisual orientation

radius of recurrent sightings: t =N = 21, P > 0.05; maximum
movements: = 1.51, N = 22, P > 0.05).

0.77,

t

However, the home range area and theradius of recurrent sightings is significandy

greater in males than in subadults (home= 2.66, N = 26, P < 0.05;
range: trecurrent sightings: t = 3.12, N = 28, P <0.01).

Special attention should be given to the

movement of marked juveniles.

year (one of them was at a distance of 180m; another had formed a home range 23 mfrom the marking point). Altogether, 18
juveniles were marked, of which 14 were
not encountered during the same year, and4 occurred twice each. It may be assumed
that in Przewalsky's Gecko, juveniles aremode, similar to theagamid, Phrynocephalus versicolor(Semenov and Borkin, 1985). Having
hatched, juveniles do not form homein

The home ranges of these geckos
overlap greatly (Fig. 7), irrespective of sex.
Obviously Przewalsky's Geckos are notterritorial.
Their spatial distribution

corresponds to thescheme typical lizards

actively looking for their prey, living in

Unlikeadults (see above), only 2 of 15 juveniles
marked in 1981 were recorded in the next

thedispersal

ranges, but disperse and only setde after the

Movements ofoverwintering.
exceedthe maximum
juveniles may
firstAsiatic Herpetological Research

February 1992

Vol. 4, p. 107

FIG. 9. Individual ranges of the gecko, T. przewalskii in 1981. Open triangle: records of lizards captured
only once. Solid line: arbitrary boundary of individual ranges.

movements of adults (see above).
Shelter

Strong wind and drizzling rain do notdecrease the activity of geckos noticeably.
Distinct periods of increased and decreased
activity are evident at different times not

Przewalsky's Geckos use their own
burrows and those of rodents as shelters.
Gecko burrows are, as a rule, made at thebase of bushes, with a semicircular
opening. The length of the burrow is a few
dozen centimeters.

clearly related to any weather conditions.
Such periods are not restricted to post-

Activity and Temperature

The cloacal temperature in 45 geckos
measured from 22:00 to 23:30 hours at
three different localities ranged from 17.5

Przewalsky's Geckoisexclusively

nocturnal. This is its distinction from manyother "nocturnal" representatives of the
Gekkonidae, which are characterized bymixed or crepuscular activities (Szczerbak

and Golubev, 1986). According to Obst
(1963), in the Galbyn-Gobi, in the first 10
days of September, geckos were active
between 20:00 and 24:00 hours. We
observed active individuals from 21:50 to
04:00 hours, at air temperatures of 16-29.5°C and ground temperatures of 18-29 °C.

sunset hours, as in some other gecko
species (Pianka and Pianka, 1976; Cooper
et al., 1985). This ecological aspect of thisspecies requires special study.

Figure 10 demonstrates theofcloacal temperature to air
relationshipin25
individuals of different
temperature
and
sex
the
[in
vicinity of Ekhiyn-Gol
age
and Shara-Hulsny-Bulag oasis in the southof Bayanhongor Aymag (Province)]. As arule, cloacal temperature is slightly lower
than air temperature by about 1°C. In only
to 28.5 °C.

was cloacal temperaturethan
airhighertemperature. This may havebeen the result of stress since these lizards
six individuals

Vol. 4, p. 108

Asiatic Herpetological Research

24

February 1992

30

26

Air Temperature
FIG. 10. The relation between air and cloacal temperatures in T. przewalskii.

were either being pursued or handled for along time.
During a few minutes offactor of by the combined action of lighthandling, the cloacal temperature in a gecko
may increase by 3-4°C. Figure 1 1 shows

alone. In any case, suitable temperatures
occur not only at night, but also in theevening and morning (Fig. 4), but geckos
were never met during the light of day.

the temperatures of 1 1 geckos from thevicinity of the Shara-Hulsny-Bulak Oasis.

Measurements were made on July 5, 1982,
The sanda strong wind.
temperature was slightly higher than the airtemperature. The temperature of the backof the lizards slightly exceeded the cloacal
temperature. In 20 individuals caught in
the Dzamiin-Huren-Els area in late summer

and temperature, rather than by temperatureDietduring(August 31, 1982), the cloacal temperature

was 17.5-19.8°C, averaging 18.3°C, withan air temperature of 18.0-1 8. 2°C. The
temperature of the sand surface was 1 8°C,
and the temperature of the ground air layer
dropped from 17.5 to 16.2°C during the
22:00-23:20 hour measurement period. It
should be noted that lizards were caught
and measurements made during a weak

Analysis of the stomach contents ofGecko (Table 2)demonstrates that, like the Middle Asian T.
scincus, (Bannikov et al., 1977) thisspecies feeds mainly on beetles.

Przewalsky'sSpecialization in feeding on beetles
manifests itself in the development of arobust jaw apparatus.
Relatively lowofdiversity parameters
feeding are theof
thisconsequencespecialization (Table
Similar values are only known for3).
some populations of the agamid lizard,

scanty and diverse to make any final
conclusions on the thermobiology ofPrzewalsky's Gecko.

Phrynocephalus versicolor feeding mainly
on ants. They are much higher in otherlizards of the Transaltai Gobi (Semenov,
The largest food items are the1986).
tenebrionid darkling beetles (18x6 mm),and their larvae (24x4 mm) [these are solarge that only one beetle or one larva is

The strictly nocturnal activities of thisspecies seem to be controlled by a light

consumed at a time]; the smallest are ants
(1x3 mm). Sometimes geckos may devour
larger objects. A gecko consumed an adultrain.

On the whole, the above data are tooAsiatic Herpetological Research

February 1992

Vol. 4, p. 109

4>

U
3
«
t-

a.

E

H

"T

20

30

40

50

Time (min after 22:00)
FIG. 1 1.

Environmental and body temperatures in T. przewalskii versus time.

lizard, Phrynocephalus versicolor (about 80
in length, including the tail, and 10mmmm

width) placed in the same bag with it.
According to the observations of Szczerbak
and Golubev (1986), these geckos will
attack small lizards in a terrarium. The
average weight of a full stomach reaches
7.8% of body weight.

quite rapidly over the period of several
hours (Obst, 1963).

inTeratoscincus scincus molts not less than
three times during the season.

Accordingto observations in captivity, molting takes

5-6 days (Szczerbak and Golubev, 1986).

Behavior
Molting

Prolonged observations of marked
lizards helps to record the frequency ofmolting (Semenov and Shenbrot, 1986a).
Approximately half of the geckos observedin 1981 and 1982 molted during the periodof observation. Only one individual (asubadult male) made two molts during one
season: one in the middle of July and one in
the middle of August, 1981. As all molted
geckos were supplied with dorsal numbers
again, and since in the next year these
individuals were once again without
numbers, it may be stated that molting takes
place more than once a year. According toour data, there are no special molting

As was noted above, Przewalsky's
Geckos do not protect territories.
Nevertheless, in the corral, distinct
aggressive behavior was observed: an adultdarted at an approaching young gecko andpowerful blow to its head(perhaps having bitten it); one of thememitted a short acoustic signal.
Przewalsky's Geckos have no permanent"observation posts" on the home range, andseemingly do not protect either the range ortheir shelters. Such protection is known
for most of the Gekkonidae (Stamps,
1977). The aggressive behavior must be
inflicted a

related to the support of the individual
distance (Carpenter, 1965).

periods, since molting individuals wereobserved throughout our observation
period. Like other geckos, Przewalsky's
Gecko devours the shed skin layers (foundintwostomachs).

Accordingtoobservations in a terrarium, molting occurs

its
movements,
by
is
a
Gecko
typicalpredator
Przewalsky's

Judgingthat actively forages for its prey, in contrast

to most other geckos that mainly wait forprey (Stamps, 1977).

It isinteresting toVol.4, p. 110

Asiatic Herpetological Research

TABLE. 2. Stomach contents of T. przewalskii (N=14).
Food items

February 1992

February 1992

Asiatic Herpetological Research

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