Green lizards in central Europe: status, threats and ... - VipersGarden

BOHMB, W., BISCHOFF, W. & T. ZlEGLER (eds.): HERPETOLOGIA BONNENSIS, 1997: 105-113
Green lizards in central Europe: status, threats
and research necessary for conservation
KERSTIN ELBING, HANS-KONRAD NETTMANN & SIIJCE RYKENA
Introduction
Green lizards (genus Lacerta s.str.) form a real clade rather distinct from other lacertid
groups (MAYER & BENYR 1994). Mainly the L. lepida IL. princeps species group, which
is commonly lumped with green lizards (e.g. in the most common field guide of ARNOLD
& BURTON 1978), is forming quite a different, not closely related clade (Lurz & MAYER
1984, RYKENA & NETTMANN 1986, MAYER & BENYR 1994), recently designated as separate
genus Timon (MAYER & BISCHOFF 1996). Species number in green lizards has increased
within the last 15 years. Currently eight species are recognized, L. schreiberi, L. strigata,
L. pamphylica, L. trilineata, L. media, L. bilineata, L. viridis, L. agilis, the last five of them
are polytypic.
Taxonomic status
Beside of the sand lizard, L. agilis, which is not subject of this paper, the green lizards
are represented in Central Europe by two forms, formerly known as L. viridis.
BOKER (1990) demonstrated marked differences in thermal requirements and activity pattern,
comparing his own ecological observations from populations at the Rhine with PETERS
(1970) data from Brandenburg. This as well as arguments given by NETTMANN & RYKENA
(1984) supported the hypothesis of B6HME (1978) about two ecologically different adapted
forms, representing different glacial refugia.
Based on results from hybridization studies RYKENA (1991) had stated, that the former I.
viridis consists at least of two distinct species. That means, the former western subspecies
is genetically isolated enough to be recognized as a distinct species Lacerta bilineata DAU-
DIN. Recently AMANN (1995) supported this specific differentiation of the two forms, based
on electrophoretic data. His results, together with further hybridization data will be published
soon (AMANN et al. in press.).
L. bilineata is present in Western Germany, Switzerland, France, Northern Spain and Northern
Italy. The systematic status of the green lizards in the Italian peninsula is still not
known sufficiently (NETTMANN & RYKENA 1984). But, based on preliminary observations
about coloration of hatchlings and adults, we prefer to list all green lizards from Italy with
sometimes unclear subspecific status tentatively as belonging to L. bilineata. Likewise the
animals from the Balkan Peninsula and from Northern Anatolia, described as different subspecies,
belong to L. viridis (fig. 1).
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Fig. 1. Distribution of Lacerta bilineata and Lacerta viridis.

The boundary between the two species, presumably in Slovenia and Croatia, hasn't been
studied yet. The main problem is, to distinguish the two species in the field, because the intraspecific
variation in pholidosis characters as well as in colour pattern is greater than the
interspecific variation. Characters like prominent white stripes, which are often taken as typical
in green lizard females from western Europe, occur in both species, although perhaps
in different frequencies. Up to now only the hatchlings of the two species can be distinguished
easily by coloration characters. In both species the hatchlings are dorsally greyish
brown to bronze, sometimes with more or less prominent light lines and also light spots on
the flanks. But the head sides and the throat is only whitish in L. viridis hatchlings while
L. bilineata hatchlings exhibit a characteristic green colour at these head regions (RYKENA
1991, NETTMANN 1995, RYKENA et al. 1996 a, b).
This taxonomic situation requires the new name Lacerta bilineata in the species list of
Great Britain, France, Spain, Switzerland, Italy, Monaco and San Marino, while in Germany
and perhaps Croatia and Slovenia both species exist. In all other countries no changes in the
lists are necessary.
Distribution in Central Europe
In most parts of central Europe, (roughly defined as the area between 6° and 27° east of
Greenwich and between 46° and 58° northern latitude) only isolated populations of either
species occur in climatically favourable regions. The south-eastern part of the defined square,
which belongs to the continuous distribution area of L. viridis, is neglected in this paper
as well as the southern margin, where L. bilineata exists more or less continuously.
L. bilineata exists in the valleys of Rhine, Mosel and Nahe. In the middle Rhine region
as well as in the valleys of Mosel and Nahe several viable populations are known, forming
a distinct distribution area (NiEHUis & SOUND 1996). In the upper Rhine region only one
or two isolated populations in the "Pfalz" and the populations in the "Kaiserstuhl" were
known until recently in the French part of the valley in the Elsass several populations were
found (GOOSE & CASTANET 1989), thus confirming the proposed immigration through the
valleys of Rhone, Saone and Doubs. The Rhone valley region in Switzerland as well as the
southern side of the Alps belong to the continuous distribution area of L. bilineata and are
not discussed here.
The distribution area of L. viridis reaches Central Europe along the Danube valley up to
Passau. Isolated populations exist in Bohemia and in Brandenburg, while south Moravia and
Slovakia as well as Hungary, Romania and Croatia belong to the continuous distribution
area. From Poland only one observation was reported in the last 50 years (BiELAWSKi &
RAMIK 1972). This population from south Silesia is presumably extinct (MA^LAK 1995). It
was situated just in the region, where an migration from Moravia to the northern lowlands
was suggested by PETERS (1970), although no old observations from Silesia have been confirmed
before. From northern Poland no recent records exist. CORBETT (1989) mentioned
some few remaining populations in Poland in the 1960s, which was an optimistic interpretation
of PETERS (1970) review. Old records exist from South Pomerania and from the Wistula
valley around Torun (Thorn).
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Habitat types
Typical habitats of L. bilineata are vineyards and other old and extensive agricultural
areas at south exposed slopes of river valleys, often in connection with railroads, roads, or
remains of such structures. Real xeric places are not used while rather moist places with
dense vegetation must be present in the habitat (B6KER 1990). Similar habitat types are recorded
from the upper Rhine region.
The!,, viridis habitats in Bavaria, Upper and Lower Austria as well as in Bohemia are also
south exposed slopes of river valleys. In the presumed natural forests at these slopes patches
of open landscape has been created formerly either by man's activities in growing wine
or fruit trees and grazing sheep or cattle, or by erosion caused by the rivers. Both factors
are no longer very effective (NETTMANN 1996). Open habitats at the river banks, which are
still important parts of the habitats at smaller rivers in Bohemia (STRODICKE 1995), are at
the Danube normally isolated from the slopes by roads with much traffic, preventing migration
from slopes to the banks. Thus the former habitat forming dynamics, either natural or
cultural, are lost almost irreversibly and has to be replaced by management measures
(NETTMANN 1996).
In Brandenburg a similar type of habitat, meadows, fruit gardens and roadsides near villages
was recorded from the Oder valley, but those populations near Oderberg, at the northernmost
well documented point of the species, have gone extinct in the early fifties (PE-
TERS 1970). From the large xerotherm slopes at the Oder valley with a steppe vegetation
with many pontic elements no records of L. viridis exist.
The typical habitat type of L. viridis in Brandenburg, where the species has survived, is,
according to PETERS (1970) and PAEPKE (1970) a roadside or railroadside in large pine forest
on poor sandy soil. Own observations (ELBING 1996) indicate, that also forest sites mixed
with heath, and other patches of open landscape in large forest regions are suitable habitats.
Thus the amount of potential habitats in Brandenburg and also in adjacent regions is
much larger than expected before, taking in account the large military training areas of the
former soviet troops.
Status, threats and necessary research
L. bilineata in the Rhine river system
In the middle Rhine region intensive mapping of L. bilineata habitats and protecting measures
were undertaken within the last 10 years. From these it has been stated, that despite
of the losses in habitats and populations in the last 100 years, the present situation is rather
stable and more populations are known today than 20 years ago (NffiHUis & SOUND 1996).
There are several areas, where the populations are regarded as viable and not very endangered
(GRUSCHwrrz 1992, NffiHUis & SOUND 1996). Nevertheless their habitats require management
measures instead of the former agricultural activities. The situation in the Pfalz
seems to be more critical. In this region intensified mapping is necessary to improve the
data base. The recent paper of NffiHUis & SOUND (1996) summarizes the actual threats in
Rheinland-Pfalz as habitat losses, mainly due to changes in the land use systems. In the
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area of Kaiserstuhl and Tuniberg in Baden L. bilineata seems to be rather common in regions
with old vineyards. But the species has difficulties to resettle the large new winefield
regions, which have been constructed in the 1970s (Fkrrz pers. com). From the populations
in the Elsass we have no information. Here as well as in south Baden further mapping activities
will be useful.
To sum up, the knowledge about the actual distribution of L. bilineata is quite sufficient
concerning the Mosel-Rhine region. But on the western side of the upper Rhine plain mapping
activities seem necessary. From all regions more detailed information about population
structure and dynamics, home range diameters and habitat use are needed, to develop more
detailed conservation programs. Also information about effects of pesticide use in the wine
fields and other agrochemical influences are necessary. The main threats of the L. bilineata
populations in the Rhine valley are obviously the changes in agriculture. Measures, which
replace former agricultural activities are necessary and already planned in some regions. In
the long run and for the benefit of L. bilineata it seems reasonable, to develop a more ecological
form of agriculture in and around their habitats.
L. v i r i d i s in the Danube system
At the upper Danube valley the situation of L. viridis seems to be comparable to that, described
for L. bilineata at the middle Rhine, as far as scattered observation data can tell.
The data base in the Austrian region is smaller, but as far as we know, similar habitat
threats result here from similar changes in the land use system. Therefore similar research
activities will be necessary.
The situation of the green lizard in the lowlands of Austria, Hungary, Moravia, Slovakia,
Croatia and Romania, that means in the region of supposed continues distribution, is not to
be discussed here. Much more habitat types will be found there and more different ecological
conditions will be observed, as normally in a species core area (B6HME 1978). Despite
of this the species seems to be endangered in some of these regions also, mainly by habitat
loss due to intensified industrial agriculture. But in most parts of this "continuous distribution
area" the mapping data are insufficient, therefore statements about the "continuity" of
distribution and about the status of the species are hypothetical.
The Situation of£. viridis in Bohemia, in the Elbe
river system
There are several populations reported from south exposed slopes of the valleys of the
Vlatava (Moldau) and Berounka (Beraun), and also some records from the Ohre (Eger), forming
an area of scattered distribution in the Bohemian basin west of Prague. Systematic
mapping may result in further sites, where the species exist (STRODICKE 1995). A systematic
survey on the status and development of the species in this region seems necessary, but
based on the limited data no major decrease cari be stated. Also management measures
against reforestation and protection of sites against touristic development or other disturbances
seems to be necessary and take place already at some sites (STRODICKE 1995). At least
at some places the habitats seem to be the primary natural habitats in this region. Therefore
studies on population ecology in such situations are very important. Based on such data management
measures also in the upper Danube valley will become more effective.
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There are no records from the Elbe valley in Saxony, perhaps because the climatic and
ecological conditions in this valley between Tetschen (Decin) and Dresden prevent a successful
colonization by green lizards (OBST in litt.).
The Situation of L. viridis in the Brandenburg relict
populations
The green lizards in the northern lowlands, in Brandenburg and, if still existing, in northern
Poland, are forming the!,, viridis population group, which is most isolated and in the
strangest ecological situation compared to other population groups. Because of the longstanding
separation and the specific ecological conditions, where it should be adapted to, it
must be called a distinct geographical race within the definition of Bern Convention, although
a status as subspecies within the zoological nomenclature is not justified.
The map published in SCHEEMENZ & GUNTHER (1994) indicates several places, where
green lizards have been observed in the seventies, but obviously have disappeared later Besides
of some uncertain observations by foresters since 1987 only two places were known,
where L. viridis existed. KlRMSE (1990, 1994) stated, that only about 25 adults exist in the
field. Therefore a breeding program was started in the late eighties by KIRMSE and others.
The founding of a new population and some measures to stabilize the known populations
were started too (RuHE in litt.). But due to many circumstances all these measures were
more or less unsuccessful. In the conservation administration formed after 1990, sometimes
the opinion occurred, that according to PETERS (1970), the species cannot survive in Brandenburg
because of climatic reasons. Therefore it should be better to let it going extinct
there honestly. Thus no major program was started, although ROBEL tried to initiate and to
encourage basic research for better measurements.
In 1994 one of us (ELBING) started to study the known population, but also tried to find
some more. Based on the first results, we are convinced that the species in its relict situation
in Brandenburg is viable and worth for intensified conservation research activities. A
surprising experience during the intensive field work was, that the local foresters know
about the green lizards. They are proud to have them in their territories, but they don't tell
about, just to prevent major disturbances by observation activities or by collecting. Unproved
stories about major collecting activities in the late eighties are common.
Nearly all populations we know now are inhabiting forest sites and it should be possible
to find some other new populations in that kind of habitat. As of this forest management is
the striking factor in the habitat of L. viridis and any protection measure has to be in accordance
with the forest interests. But up to now ecological changes resulting from either forest
growth or pesticide use have been overlooked when the correlation of climatic change
and decrease of green lizard populations was discussed as causal. It is not to point, that insecticide
spraying or other forest activities are responsible instead of climate. But it is important
to realize, that many other factors than climate are working in the field and that we
have no data about their real effects. Contrary to older positions it is becoming more and
more clear, that the species is not simply a victim of a "natural extinction process". And
there is no evidence for an inbreeding deficiency or a limited reproductivity in the known
populations.
At first view there are some similarities to the situation of the sand lizard in England
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(CORBETT 1988) as far as the role of forest growth is concerned. But for closer comparison
the situation of L. viridis in Brandenburg is only poorly known, no natural heath habitats
exist there and the reasons for decline obviously are not clearly understood.
As of this and because of the limited number of populations in a rather limited area it
may be one of the most endangered green lizard races in Europe, which requires a protection
program implemented with applied basic research most urgently. Although it is clear
in principle, that a sophisticated forest management, resulting in a continuous but dynamic
system of suitable habitat patches is needed (ELBING 1996), much research is necessary to
create such program. The demands can be summarized in the following points:
1. Intensified mapping of suitable forest habitats in Brandenburg as well as in Poland. It
should result in more sites where I,, viridis exist.
2. Information about the lizards use of (forest) habitats and the influence of natural succession
or forest management are urgently needed.
3. Despite of the existing long term population study (PETERS 1970), more intensive studies
on population ecology and dynamics, comparing different populations in slightly different
situations are necessary.
4. Also synecological data are needed as well as data about the food supply in the populations,
because the role of insecticide use in the forest management must be evaluated.
General considerations
In both species (L. viridis and L. bilineata) comparative studies of population ecology
seem to be necessary. The aim is to understand the local adaptations, the interactions with
other species and the population dynamics in the different regions. Also the genetics of the
postglacial invasions and the differentiation in both species must be known. On this basis
it can be decided much better, which protecting measures will be useful in each special situation.
Not to argue, that protection can start only after some more years of research, but
just in contrary we think, that it is necessary to improve any conservation program continuously
by new research data.
Unfortunately nature conservation in Central Europe is becoming a discipline of administration
and laws instead of biological science. Research is often considered to be costly
and time consuming with the effect of "nothing visible in the field has happened". Also research
is taken as disturbance by the administration. Nearly any research activity in the
field needs one or several official permissions. To get them is at least time consuming, sometimes
it takes more time than the field work. Many methods, which are standard field
ecology methods in the USA or in western or southern Europe, are nearly impossible to use
in some parts of central Europe. Thus nature gets reduced to a mix of data on pollutants,
"biotope" plans, administrative papers, and protection laws, while animals and plants with
their dynamic population processes will disappear.
Summarizing the situation of the green lizards, no new administrative regulations seems
necessary at present, but an increase of knowledge about the real situation and ecological
demands of the green lizard species is urgently needed. This also includes monitoring programs
which need at least some demographic data obtained regularly. Like the weather fo-
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ecast we need continuous data, which cannot be collected incidentally. The potential of a
regular collecting of population data for monitoring ecological changes has not been tested
yet, but should not longer be underestimated.
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Authors' addresses: KERSTIN ELBING, HANS-KONRAD NETTMANN and SILKE RYKENA, Abt. Evolutionsbiologie,
Institut fur Okologie und Evolutionsbiologie, Fachbereich 2 (Biologie/Chemie),
Universitat Bremen, Postfach 330440, D-28334 Bremen, Germany.
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