Distribution and Habitat Use of Dice Snakes (Natrix tessellata) in Slovenia

Abstract

The dice snake (Natrix tessellata) is a protected species in Slovenia, whose distribution is incompletely known and only little information about its habitat use is available. We analyzed historical and recent distributional data and performed a study of habitat use to acquire relevant information for the conservation of dice snakes in Slo-venia. Using a line transect method, we compared habitats at localities of recorded dice snakes with habitats available next to the line transects in four buffer zones (10, 20, 50, and 100 m distant from the transect). All transect lines were located in areas of less than 1 km from the rivers Sava and Kolpa. In order to get a better idea on habitat selection , habitat use including all precise localities (n = 117) of dice snakes in Slovenia was analyzed. Dice snakes were recorded mainly in the lowlands throughout the country, but were rare in the northeastern part. Its presence in the river Kolpa was confirmed for the first time. More than 75% of observations were recorded within 10 meters from a water body. To a minor degree, snakes selected grasslands and urban areas along the Sava River and land covered with shrub vegetation at the Kolpa River. Forest habitats as well as agricultural land with herbaceous plants were avoided along the Sava River.

Full text

207
© 2011 Deutsche Gesellscha für Herpetologie und Terrarienkunde e.V. (DGHT), Rheinbach, Germany
Distribution and Habitat Use of Dice Snakes (Natrix tessellata)
in Slovenia
A Ž, M K, M G  K M
Abstract. e dice snake (Natrix tessellata) is a protected species in Slovenia, whose distribution is incompletely
known and only little information about its habitat use is available. We analyzed historical and recent distributional
data and performed a study of habitat use to acquire relevant information for the conservation of dice snakes in Slo-
venia. Using a line transect method, we compared habitats at localities of recorded dice snakes with habitats avail-
able next to the line transects in four buer zones (, , , and  m distant from the transect). All transect lines
were located in areas of less than  km from the rivers Sava and Kolpa. In order to get a better idea on habitat selec-
tion, habitat use including all precise localities (n = ) of dice snakes in Slovenia was analyzed. Dice snakes were
recorded mainly in the lowlands throughout the country, but were rare in the northeastern part. Its presence in the
river Kolpa was conrmed for the rst time. More than  of observations were recorded within  meters from
a water body. To a minor degree, snakes selected grasslands and urban areas along the Sava River and land covered
with shrub vegetation at the Kolpa River. Forest habitats as well as agricultural land with herbaceous plants were
avoided along the Sava River.
Key words. Squamata, Serpentes, Natrix tessellata, Slovenia, distribution, habitat use
Introduction
Knowledge of the habitat use of endangered species is
crucial for many applications, such as eective manage-
ment, impact assessments, and preparation of conserva-
tion strategies. In Slovenia, Natrix tessellata is a species
protected by European (included in Annex IV of Habi-
tat Directive //ECC, and Bern Convention )
and national legislation (Decree on the Protection of
Endangered Animal Species ), classied in the cat-
egory V as a vulnerable species according to the criteria
of the Red List of threatened plant and animal species
of Slovenia (Red Data List ). is classication was
made on the basis of scarce distributional data and in-
sucient knowledge of the status of dice snakes in Slo-
venia and would require a revision when more data be-
come available. On joining the European Community in
, Slovenia also embarked on the task of implement-
ing the Habitat Directive by designating special areas of
conservation (SAC) as a part of the Natura  net-
work. However, the dice snake is not included in Annex
 of the Habitat Directive, for which SAC should be des-
ignated. It is an “Annex -species”, which concludes that
dice snakes should be protected at all sites where they
are found naturally. However, scarce and incomplete
data on their distribution render this a dicult task. Hi-
bernation sites should also receive special attention of
conservation (C  N , C et
al. , V et al. ), but locations of such sites
are not yet known in Slovenia. ough, the dice snake is
included in all impact assessments, in most cases its sta-
tus of an “Annex -species” is not properly considered
comparing to other species. Consequently, Slovenia, by
our opinion, did not implement the Habitat Directive
which is the motivation for studies, such as the one pre-
sented herewith.
As a typical member of the genus Natrix, dice snakes
are good swimmers and divers and because of their
main prey, sh, they are bound to aquatic habitats
(K ). During the active season they remain
in the immediate vicinity of surface water at a distance
of less than  m to the water (C  N
, C et al. , N  M ,
V et al. ). Its use of habitat is therefore re-
stricted to a rather narrow belt surrounding suitable wa-
ter bodies with abundant sh, which has been shown
in many studies of herpetofaunal communities or relat-
ed ecological studies of dice snakes (e.g. L  G-
 , F et al. , M , ,
C-M et al. ). Only few anecdotal re-
cords on the diet of dice snakes from Slovenia are avail-
able, which include the bullhead (Cottus gobio), brown
trout (Salmo trutta), chub (Squalius cephalus), and frog
tadpoles (Rana sp.) as prey items (C  K
, F. K pers. comm., and our pers. obs.).
According to T () the dice snake occurs
throughout Slovenia, mainly along lowland rivers with
dense vegetation. It is also common on the coastal part
of the country at semi-saline water bodies (M ,
T ). Interestingly, it has also been recorded
in one of the karstic caves of northern or central Slo-
venia (N ). Previous data suggested that the
dice snake was missing from two major rivers (Drava
and Kolpa), since there was only one nd of a dice snake
from the upper section of Drava River and one from the
lower section of Kolpa River (T ). Besides these
generalizations and anecdotal records about the occur-
MERTENSIELLA 18 207-216 20 September 2011 ISBN 978-3-9812565-4-3

208
A Ž, M K, M G  K M
rence of dice snakes, no study on habitat use by the dice
snake has been accomplished in Slovenia. We present
herewith a review on the distribution of the dice snake
in Slovenia, supplemented with new data, an analysis of
altitudinal distribution, and habitat use on a national
scale.
Some studies on habitat use applied absolute fre-
quencies (e.g. C et al. ), without considering
habitat availability in the study area. On a regional scale
we focus on a comparative analysis of habitat use of dice
snakes in relation to habitat availability. is could pre-
sent a basis for ecient conservational guidelines for
this species in Slovenia and abroad.
Material and Methods
Study Area
Two separate study areas were included in our analysis
of habitat selection: study area “Sava Site” denes a lower
section of Sava River between Krško and Brežice (south-
east Slovenia, lat. ˚’’’N, long. ˚’’’E, mean al-
titude  m a.s.l.); study area “Kolpa Site” is a middle
section of the Kolpa River in Slovenia between Kuželj
Fig. 1. Typical habitat at the Sava River (Sava Site) in south-east Slovenia. Photo: M G.
Fig. 2 (right). Typical habitat at the Kolpa River (Kolpa Site)
in southern Slovenia. Photo: M K.

209
Distribution and Habitat of Dice Snakes in Slovenia
and Sodevci (Kuželj, lat. ˚’’’N, long. ˚’’’E,
mean altitude  m a.s.l. and Sodevci, lat. ˚’’’N,
long. ˚’’’E, mean altitude  m a.s.l.). At Sava Site
the riverbed of the Sava River is regulated and the for-
merly ooded alluvial plains are today mostly convert-
ed into agricultural elds and forest plantations (MKPG
). Forested areas are newly grown but scarce and lo-
cated mostly along the river banks. Yet, the lower part of
the river Sava still represents a relatively well preserved
habitat compared to other rivers in the lowlands of Slo-
venia. e climatic conditions in this area are typical for
a temperate continental region with a precipitation of
 mm per year and an average temperature of –
°C annually (P  O A ). In con-
trast, Kolpa Site is situated in a typical karstic landscape
in the northern Dinaric Mountains with a prevalence of
carbonate rocks. e Kolpa River represents an excep-
tion since the hydrological conditions of this region are
characterized by the lack of surface water, many subter-
ranean water systems and other typical karstic phenom-
ena. is area is one of the most extensively forested are-
as in Slovenia with over  forest cover. Most common
are beech and r forest associations (Omphalodo-Fage-
tum s. lat.). e vicinity of the Adriatic Sea inuences
this region, characterized also by its relatively high alti-
tude dierences and variable climate and weather con-
ditions. e climate is considered to be temperate con-
tinental and mountainous with average temperatures
Fig. . Study areas: the upper map (1) shows the study area Sava Site and the bottom map (2) represents the study area Kolpa
Site with transect lines (red) and habitat types indicated.

210
around  °C and precipitation around  mm per year
(P  O A ). Typical sites of both
study areas are shown in Figures  and  and the land-
scape with habitat types and transect lines is shown in
Figure .
Field Work and Data Sets
We used a line transect method adapted for the studies
on reptiles (B et al. ). All transects were lo-
cated less than  meters from the river. At Sava Site
data were gathered from May to September of  and
, whereas at the Kolpa Site sampling lasted between
April and September from  to . Field work
was conducted in suitable weather conditions (sunny to
partly cloudy) during the day. e methods dier in the
number of inspections of transect lines; each transect
line at the Sava Site was inspected once, whereas at the
Kolpa Site inspections were repeated  times. All nds
from transect lines were included in the results. Record-
ed individuals were not marked and we treated every
nd as an individual one. Localities were taken with a
hand held GPS. Field data were recorded with a stand-
ard form, including locality, date, time, habitat type,
presence and number of associated reptile species, age
class (juveniles, subadults, adults) and sex of the speci-
mens if possible. All eld work was conducted by the
rst author.
We applied three principal data sets to investigate
habitat selection and distribution. e rst set includ-
ed data collected on line transects and was used to an-
alyze habitat selection by the dice snake on a regional
scale in both study areas. e second data set was used
for habitat use on a national scale and was drawn from
eld sampling and literature data with precise geo-ref-
erenced locations. ird, we used the database of Slove-
nian reptiles maintained at the Centre for Cartography
of Fauna and Flora (CKFF) to evaluate the distribution
of the dice snake in Slovenia based on UTM grids of  x
 km. ese data include precise localities that contain
geo-referenced information (GPS coordinates) and also
geographically less precise localities that include infor-
mation based on a wide, less precise scale (example: Mt.
Snežnik, city Krško) and lack any habitat information.
Data Analysis
Habitat availability for dice snakes in the study areas
was estimated by GIS analysis of land use data (MKGP
) in a buer zone of , ,  and  meters dis-
Fig. . Distribution of the dice snake (Natrix tessellata) in Slovenia: pink shaded represent the UTM squares that contain records,
but without geo-reference (GPS) and red dots represent precise locality data, which were also used in habitat use analysis.
A Ž, M K, M G  K M

211
Results
Distribution in Slovenia
All currently known localities of dice snakes in Slovenia
are distributed across  UTM squares of  x  km
Fig. . Available habitat types (transects) and habitat types
used by dice snakes (Natrix tessellata) (localities) at study
area Sava Site with buer zones of 10, 20, 50 and 100 meters
around transect lines or capture sites. Habitat types are: water
body (W), urban land (U), forest (F), shrubs (S), grassland
(G), agricultural land with woody plants (AW), and agricul-
tural land with herbaceous plants (AH).
Fig. . Proportion of capture sites of dice snakes (Natrix
tessellata) in relation to the distance from the nearest water
body in Slovenia (n = 117).
Fig. . Available habitat types (transects) and habitat types
used by dice snakes (Natrix tessellata) (localities) at study area
Kolpa Site with buer zones of 10, 20, 50 and 100 meters
around transect lines or capture sites. See Fig. 6 for legend
on habitat.
tance from all inspected transect lines. Next, we cal-
culated habitat composition for dice snakes by apply-
ing circle buers around individual snake nds with
the perimeter of , ,  and  meters. e maxi-
mum buer includes known average home ranges of
dice snakes, which are approximately .– hectares in
size (C  N , C at al. ,
N  M ). We compared the availa-
ble habitat types in the area with habitat types actually
occupied by dice snakes using ESRI ArcView . so-
ware. e same soware was combined with the digital
elevation model (DEM ) and land use (MKGP )
to analyze habitat use on a country-wide scale from the
second data set (see above).
Fig. 8. Average land use in a 10, 20, 500 and 100 meter buer
zone around capture sites of dice snakes (Natrix tessellata) in
Slovenia (n = 117) (see Fig. 6 for legend on habitat types).
Distribution and Habitat of Dice Snakes in Slovenia

212
with  precise locality records (Fig. ). is represents
 of all UTM squares in Slovenia. e majority of lo-
calities with dice snakes in Slovenia lie between  and
 m a.s.l. (Q and Q quartile). Based on precise data
only, dice snakes have been observed from sea level, at
the saltpans of Sečovlje and at Škocjanski zatok in coast-
al Slovenia (B et al. ), to the elevation of 
m a.s.l. at Ribnica, southern Slovenia.
Habitat Use
Regional scale: A total of  dice snakes were recorded at
the Sava Site and  dice snakes at the Kolpa Site. All of
the nds were made along the river banks or very close
to the water. Maximum distance from the nearest water
body was  m (Fig. ).
At Sava Site, available habitat types are relatively uni-
formly distributed with a slightly larger portion of ag-
ricultural land with herbaceous plants, grasslands and
shrubs (Fig. : transects). ere is only little agricultural
land with woody plants available as habitat. Compari-
son between habitat availability and habitat occupied by
dice snakes (Fig. : localities) show that the snakes were
detected more oen in water, grasslands and urban ar-
eas than expected from the habitat availability. On the
other hand, snakes were found less oen in forest and
agricultural land with herbaceous plants than expected.
Fig. 9. Site of several dice snakes (observed in le lower corner of image) near a cli approximately 50–100 m above a cool
mountain stream at Zaga, at 370 m a.s.l. in northwestern Slovenia. Presumably, dice snake seek that area for thermoregulatory
activities, possibly also oviposition and hibernation, as the cool temperatures of the shady canyon below, where they would
forage, are unlikely areas to provide suitable elevated temperatures. Shaded areas, in particular in the canyon, were digitally
elucidated to get a better view on the structure and height of the cli. Photo: K M.
A Ž, M K, M G  K M

213
At the Kolpa Site, forest occupies the largest portion
of available habitat types followed by grasslands, wa-
ter, urban areas and agricultural land with herbaceous
plants (Fig. : transects). e relatively large portion of
urban areas at the Kolpa Site results from transect lines
positioned mostly on roads along rivers and passing
through villages. Half of the dice snakes were captured
in the vicinity of water (Fig. : localities- m). In com-
parison to the habitat availability, dice snakes selected
water and shrub habitats more oen than forests and
grasslands (Fig. ).
National scale: Habitat use on a country-wide scale
shows that most dice snakes (.) were found in the
water or water was within a  m buer zone around
the capture sites (Fig. : SLO- m). On a larger scale
( m buer around capture sites), habitat types
were more balanced between forest (.), grassland
(.) and water (.) (Fig. : SLO- m). e ma-
jority (about ) of all precise localities (n = ) have
been recorded close to a water body (at a distance less
than  meters), and only few nds were located farther
away. Tthe farthest distance measured was  m in Laze
pri Predgradu (Fig. ).
Discussion
Distribution of the Dice Snake in Slovenia
e current data of dice snake nds in Slovenia sug-
gest that the species is relatively uniformly distributed
throughout the lowlands of the country and that it oc-
curs in the vicinities of all major rivers, such as Drava,
Sava, Kolpa and Soča, except for Mura River in north-
eastern Slovenia, where it seems to be rare (Fig. ).
From the Mura River in NE Slovenia there have been
only two records of dice snakes in our data base, one
from a gravel pit at Zgornje Konjišče and the other from
Dokležovje. e local rarity and absence of dice snakes
Fig. 10. Dice snake, Natrix tessellata, from the cli in Fig. 9.
Photo: K M.
from the eastern part of Slovenia is in accordance with
a similar lack of data in neighboring areas of Austria,
Hungary, and Croatia (C et al. , P et al.
, J H et al. ), aside from the re-
cent recovery of dice snakes in Styria (K  M-
 ). It is not clear, however, whether this reects
a real lack of dice snakes due to extinction aer historic
degradation of once populated habitats in eastern Slo-
venia and related landscapes across the border. Alter-
natively dice snakes may have not found suitable habi-
tat in this region that could have promoted the evolu-
tion of a large population. However, we attribute this
to a lack of recent search eorts in NE Slovenia, because
K  M () report on the recoloniza-
tion of dice snakes from Graz to the Slovenian border
along the once heavily polluted Mura River aer a mas-
sive program was installed to rehabilitate that river sys-
tem. Subsequently, dice snakes have been detected since
the s at several locations on the Austrian side along
the section, where the Mura River constitutes the bor-
der between Austria and Slovenia (K  M
). It would require studying several factors to un-
derstand the reasons for the presence or absence of dice
snakes in this region of Slovenia. On the other hand, in
other parts of Slovenia dice snakes are better connected
with populations from neighboring countries, such as
dice snakes from the rivers Sotla and Kolpa adjacent to
Croatia (J H et al. ). Similarly, the dice
snake is distributed throughout the whole region along
both sides of the border with Italy (S  G
, see Fig. ).
Some regions in Slovenia are less suitable for the col-
onization of dice snake because of the lack of surface
water, such as higher parts in the Slovenian Alps and
high-karst region in the Dinaric Mountains. e species
is present in some northwestern parts of Slovenia, and
we expect it to be more frequent because cool streams in
the Julian Alps apparently do not prevent the coloniza-
tion of dice snakes (R & B , and Figs.
, ). Currently we lack data from the middle section of
the river Sava (between the towns Litija and Hrastnik)
and from some other larger rivers of Slovenia, e.g. the
middle section of Krka River, Ledava River, Reka River,
which is most likely due to lack of recent research eorts.
It is already known from other reports that dice snakes
occur also in brackish waters of lagoons, salt marshes,
river mouths, and sea water (G et al. ,
K , M ). e Sečovlje saltpans in
south-western Slovenia form a big network of ditches
with brackish water and suitable hunting places for dice
snakes. Another area with similar landscape features,
but with fresh water, is the Ljubljana moor, which has
historically spanned over a large area of central Slove-
nia. Nowadays, the wetland is a large network of ditches,
strongly aected by agriculture and surrounded by ur-
ban landscape and karstic Dinaric Mountains. Yet, it still
provides suitable habitat for dice snakes.
Distribution and Habitat of Dice Snakes in Slovenia

214
Habitat Use on a Regional Scale
In the lower section of the Sava River (Sava Site), we
found dice snakes almost exclusively on river banks cov-
ered with shrubs or woody plants. Although the resolu-
tion of the land use data was not as high as eld data ob-
tained directly from the snakes’ capture sites, the results
still show that agricultural land represented a substan-
tial part of the habitat used by dice snakes. However, this
does not necessary mean that dice snakes were living in
agricultural land, since we applied a circle buer around
the capture sites for analysis and agricultural land could
be included in the results due to its proximity to a river
habitat and not because it would have been actively se-
lected for by dice snakes. Agricultural elds and inten-
sively cultivated grasslands are common components of
the Sava plains today, oen leaving only a narrow belt of
trees or shrubby vegetation of approximately two meters
between river banks and agricultural land. Our results
here imply that although the landscape is intensively
cultivated, a narrow belt of suitable structure along the
water body can assure sucient habitat quality for dice
snakes. is is in accordance with similar results from
other parts of Europe (e.g. G et al. , M-
 , , C  N , C
et al. , , K  M , M et al.
, N  M , V et al. ).
e area along the Kolpa River (Kolpa Site) is mostly
covered with forests with little agricultural land because
of poor soil conditions. e area is also scarcely inhab-
ited, although there are several small villages with up to
 houses alongside the river. Our results point to the
importance of shore habitats that are anked by shrubby
vegetation but contain no or little forests. Similarly to
other studies (Z  K , C
et al. , M et al. ), dice snakes favored sites
covered with moderately dense vegetation. e banks of
the Kolpa River are densely overgrown with scrubs or
trees, except where remains of old dams of water mills
provide an opening of approximately  meters width.
Such old rocky dams are favorable basking spots for dice
snakes, where they also nd many shelters in the rock
crevices and under scrubs and trees. ese dams and the
occasional rocky outcrops apparently provide the dice
snakes with sucient access to solar radiation to main-
tain relevant physiological processes by thermoregula-
tion. It indicates that some human infrastructure pro-
vides suitable habitat for dice snakes or might in some
cases even increase habitat suitability, as has also been
suggested elsewhere (M , , C et
al. , K  M , M et al. ).
At least this seems to be the case in areas with high for-
est cover and with open structures that oer plenty of
shelter. Additionally, the Kolpa River contains substan-
tial segments with natural riverbed, exposed to river
erosion with changing depths and shoals that provide
a structurally diverse place for dice snake to forage and
nd shelter.
Habitat Use and Altitudinal Distribution
on a National Scale
In Slovenia, the dice snake occurs in the vicinities of
all lowland water bodies with a large supply of sh. It
prefers relatively open shores that are overgrown with
grassy, shrubby or moderate tree vegetation. Some dice
snake nds were also associated with urban areas. e
smallest portion of habitat types used by dice snakes
pertained to agricultural elds, suggesting that dice
snakes prefer an uncultivated landscape.
In Slovenia, the dice snake usually occurs below 
m a.s.l., whereas the average elevation of Slovenia is 
m a.s.l. (range in Slovenia,  to  m a.s.l.). Com-
pared to other countries, the low altitudes occupied by
dice snakes in Slovenia are surprising, since this species
occurs up to ~ m a.s.l. in the Swiss Alps (M
, G et al. ), close to  m a.s.l. in
Austria (C  T ), and at least up to
 m a.s.l. in northern Italy (S  G ),
although the latter record is supposed to be an erratic,
single stray nd. But indications of once existing popu-
lations have been found in the same area up to approxi-
mately  m (B et al. ). Dice snakes can
occur up to  m a.s.l. in southern countries (G
et al. ) and even up to  m a.s.l. in central Asia
(B et al. ). At present it is not clear whether
the absence of dice snakes from higher regions in Slo-
venia reects true absence or insucient eld work in
these areas. We hope that future studies will shed more
light on the distribution and ecology of dice snake in
Slovenia.
Acknowledgments
We thank all who contributed data to the Centre for Car-
tography of Fauna and Flora and/or to the Societas Herpe-
tologica Slovenica and made preparation of this work possi-
ble. Special thanks to A. L from CKFF for preparation
of maps included in this article. Field work in study area Sava
Site was conducted as a part of a project titled “Inventarisa-
tion of Fauna and Flora and Habitat Type Mapping in the Area
of Planned Power Plants Brežice and Mokrice” funded by Hi-
droelektrarne na Spodnji Savi, d.o.o. Field work in study area
Kolpa Site contributed to a M.S. thesis by the rst author at
the Department for Biology, Biotechnical Faculty, University
of Ljubljana, Slovenia.
References
B, A.G., D, I.S.  A.K. R ():
Zemnovodyne i presmykajuschtschiesja SSR. – Moaskau
(Isdatel’stvo “Mysly”).
B, G., C, T., G, M., G, G., J,
M., K, E., P, D., R, D., Š, M.,
T, M.  R. V (): Quell che rimane di un
antico mare, Baia di San Canziano: ritrovamenti fossili tra
l’imodizia. – Falco, Koper : –.
A Ž, M K, M G  K M

215
B, R., M, F.  L. S (): Le attuali con-
oscenze sull’erpetofauna Bresciana. – Natura Bresciana, Ann.
Mus. Civ. St. Nat., Brescia : –.
B C (): Law on ratication of Convention of
conservation of free living European ora and fauna and their
natural habitats (Ur. l. RS /).
B, S.T., A, D.R., B, K.P.  J.L. L
(): Distance Sampling: Estimating Abundance of Biologi-
cal Populations. – Chapman and Hall, London.
C, A.  F. T (): Atlas der Amphibien und
Reptilien Österreichs. – Neue Denkschrien des Naturhist.
Museum Wien, Bd. .
C, A., G, H.  F. T (): Atlas zur
Verbreitung und Ökologie der Amphibien und Reptilien in
Österreich: Auswertung der Herpetofaunistischen Datenbank
der Herpetologischen Sammlung des Naturhistorischen Mu-
seums in Wien. – Umweltbundesamt, Wien.
C, V.  M. K (): Report on eld work of the
group for reptiles. - In: S et al. (Eds.): Biology Stu-
dent Research Camp Lovrenc na Pohorju . – Biology Stu-
dent Society, Ljubljana: – (in Slovene).
C, M., F, E., L, L.  V. T-J ():
e ecology of the western whip snake (Coluber viridiavus
Lacépede, ) in Mediterranean Central Italy. – Herpetozoa
: –.
C, A.E.  M. N (): Studio telemetrico
dell’habitat della Biscia tassellata, Natrix tessellata (Lauren-
ti, ) in tre popolazioni del Cantone Ticino (Svizzera). –
Bollettino della Società Ticinese di Scienze Naturali : –.
C, A.E., N, M., M, K.  B.R. S
(): Monitoraggio della Biscia tassellata, Natrix tessellata
(Laurenti, ) nel Cantone Ticino (Svizzera). – Bollettino
della Società Ticinese di Scienze Naturali : -.
C, A.E., N, M.  K. M (): Dierent hab-
itat use of dice snakes, Natrix tessellata, among three popula-
tions in Ticino Canton, Switzerland. – A radiotelemetry study
Mertensiella : –.
C-M, S.-D., G, I., C-L, A.-S.,
S, I., S, A.  H.V. B (): Contributions
to knowledge regarding the geographical distribution of the
herpetofauna of Dobrudja, Romania. – Nort-Western Journal
of Zoology /: –.
D   P  E A S
(): Decree of endangered animal species (Ur. l. RS /)
(in Slovene).
F, E., C, M., L, L.  U. A (): e
prey spectrum of Natrix natrix (Linnaeus, ) and Natrix
tessellata (Laurenti, ) in sympatric populations. – Herpe-
tozoa (/): –.
G, J.-P., C, A., C-I, J., D, D.,
G, K., H, P., L, J., M, H.,
M-R, J.P., M, H., O, M.E., S-
, T.S., V, M.  A. Z (): Atlas of Am-
phibians and Reptiles in Europe. – Societas Europaea Herpe-
tologica & Muséum National d’Histoire Naturelle, Paris.
G, M., L, S., M, K.  V. L (): Na-
trix tessellata (Laurenti, ) – Würfelnatter. – In: B,
W. (Ed.): Handbuch der Amphibien und Reptilien Europas,
Vol./Schlangen II: Colubridae  (Boiginae, Natricinae). –
AULA-Verlag, Wiesbaden, Germany.
H  (): Council Directive //EEC of .
May  on the Conservation of Natural Habitats and of Wild
Fauna and Flora.
J H, B., K, E., L, B., P-L,
M., S, J., T, Z.  N. T (): Red Book
of Amphibians and Reptiles of Croatia. – Ministry of Culture,
State Institute for Nature Protection, Republic of Croatia. Za-
greb.
K, W.  K. M (): Eects of rehabilitation of the
polluted river system Mur in Styria, Austria, and construction
of hydroelectric power plants on sh fauna and distribution of
the dice snake. – Mertensiella : –.
K G. (): e Snakes of Europe: All Species from West
of the Caucasus Mountains. – Edition Chimaria, Frankfurt am
Main.
L, S.  M. G (): Zur Autökologie der Würfel-
natter, Natrix t. tessellata (Laurenti ), in Deutschland. –
Mertensiella : –.
M, K. (): Untersuchung zur Morphologie und Taxono-
mie der Würfelnatter Natrix tessellata (Laurenti ) in der
Schweiz und im südlichen Alpenraum. – M.S. thesis, Zoologi-
cal Museum, University of Zürich, Switzerland.
M, K. (): Die Würfelnatter am Lopper. – In: Amphibi-
en und Reptilien in Unterwalden. – NAGON Vol. II: –.
M, K. (): Die Würfelnatter am Brienzersee. – In: Jahr-
buch , Uferschutzverband uner- und Brienzersee. –
UTB Selbstverlag, un, Switzerland: –.
M, K. (Ed.) (): e Dice Snake, Natrix tessellata: Biol-
ogy, Distribution and Conservation of a Palaearctic Species.
– Mertensiella , DGHT, Rheinbach, Germany.
M, K., C, A.E., N, M.  B.R. S
(): Monitoring and assessment of the distribution of the
dice snake in Ticino, southern Switzerland. – Mertensiella :
-.
MKPG (): Actual use of agricultural pieces of land (Raba_
beta_, Oktober ). – Ministry of Agriculture,
Forestry and Food. – Available at http://rkg.gov.si/GERK/ (in
Slovene).
M, N. (): Reptiles (Reptilia) of Slovenia. – Institution of
Republic of Slovenia for Matters of School, Ljubljana (in Slo-
vene).
N, C.  K. M (): Migration behavior of endan-
gered dice snakes (Natrix tessellata) at the River Nahe, Ger-
many. – Mertensiella : –.
N, T. (): Terrestrial fauna from caves in northern and
central Slovenia, and a review of systematically and ecologi-
cally investigated caves. – Acta Carsologica : –.
P, D.  M. O A (): Slovenia: Landscape
and People. – Založba Mladinska knjiga, Ljubljana (in Slo-
vene).
P, M., S, P.  G.M. S (): Magyarország her-
petológiai atlasza / Herpetological Atlas of Hungary. – Var-
angy Akciócsoport Egyesület, Budapest, Hungary.
R D L (): e rule book of classication of endan-
gered plant and animal species in the Red Data List, Annex
: – Reptilian Red Data List (Ur. l. RS /) (in Slovene).
R, M.-O. & R. B (): Die Amphibien und Rep-
tilien der Julischen Alpen. – Sauria (): -.
S, S.  A. G (): Natrix tessellata, dice snake. – In:
S, R., D, G., R, E.  F. B (Eds.): At-
las of Italian Amphibians and Reptiles. – Edizioni Polistampa,
Societas Herpetologica Italica, Firenze.
T, S. (): An overview of distribution of reptiles in Slove-
nia. – Annales Series Historia Naturalis, Koper (): –
(in Slovene).
Distribution and Habitat of Dice Snakes in Slovenia

216
Authors
A Ž, M K, Societas Hrpetologica Slovenica, Društvo za Preučevanje Dvoživk in Plazilcev, Večna pot
, SI- Ljubljana, Slovenia, and Biotechnical Faculty, University of Ljubljana, Večna pot , SI- Ljubljana, Slovenia;
e-mail: anamarija.zagar@gmail.com; M G, Center for Cartography of Fauna and Flora, Antoličičeva , SI-
Miklavž na Dravskem polju, Slovenia; K M, Siebeneichenstrassse ,  Merenschwand, Switzerland.
T, S. (): Reptiles (Reptilia). - In: K, B. (Ed.):
Study of Distribution of Important European Species in Slove-
nia. Final Report. – Prirodoslovni muzej Slovenije, Ljubljana:
– (in Slovene).
T, S. (): Snakes why do we fear them?!? – Prirodoslovni
muzej Slovenije, Ljubljana (in Slovene).
V, M., V, P.  K. M (): Ecology and
ethology of dice snakes (Natrix tessellata) in the city district
Troja, Prague. – Mertensiella : –.
Z, P.  W. K (): Herpetological inventory
of the lower Mur river valley, with special regard to Natrix tes-
sellata tessellata (Laurenti, ). – Herpetozoa (/): –.