ECOLOGIA BALKANICA 2009, Vol

ECOLOGIA BALKANICA 2009, Vol. 1 November 2009 pp. 27-39

Risks and Opportunities of Urbanization – Structure of Two Populations of the Balkan Wall Lizard Podarcis tauricus (Pallas, 1814) in the City of Plovdiv

Ivelin A. Mollov*, Miglena V. Valkanova

University of Plovdiv “Paisii Hilendarski”, Faculty of Biology, Department of Ecology and Environmental Conservation, 24 Tsar Assen Str., 4000 Plovdiv, BULGARIA *E-mail: [email protected]

Abstract. The current study analyzes the structure and some features of two urban metapopulations of the Balkan Wall Lizard (Podarcis tauricus (Pallas, 1814)) from Nature Monument (NM) “Mladezhki halm” and Nature Monument “Halm na osvoboditelite” in the city of Plovdiv (South Bulgaria). In both study sites, the Balkan Wall lizard inhabits exclusively the interior of the hills and prefers mainly open areas with rare grass and shrub vegetation. The recorded dominant plant species are not autochthonous for the hills, but gradually displaced with many decorative species, used widely in the gardening and the city parks. The population abundance from both hills is relatively low, with higher values in NM “Mladezhki halm” and generally shows a decrease pattern for the two year period. In the hills of Plovdiv, the Balkan Wall lizard shows a bimodal diurnal and seasonal activity. Both metapopulations showed a sex ratio close to 1:1 with a slight superiority of the females (1:1.29), but with no statistically significant deviation. The age structure of both metapopulations is almost identical - the highest percentage takes the adults, followed by the subadults and juveniles, with no significant deviations from the normal ratio. The possible reasons for the contemporary distribution and population structure of the Balkan Wall lizard are discussed. Historic land use change and its effect on the populations are discussed as well. The main risks for this species in the city of Plovdiv are construction and forestation (destruction of open terrains). Nevertheless, the Balkan Wall lizard seems to have successfully overcome the risks of urbanization and its population seem stable and sustainable.

Key words: Podarcis tauricus , metapopulations, urban environment, Plovdiv, Bulgaria

Structure of two populations of the Balkan Wall Lizard Podarcis tauricus …

Introduction their unique geomorphologic formations Urbanization is one of the most drastic and certain biodiversity conservation role, changes that can be imposed on an three of them were protected by the law environment, fragmenting the land into a and were declared as “nature landmarks”, mosaic of patches of differing size and according to the Bulgarian legislation. shape that are surrounded by the urban The aim of the current study is to matrix - cleared areas, roads, buildings and analyze the structure and some other modified habitats (DICKMAN , 1987). characteristics of two local metapopu- Most of these patches are small in size and lations of the Balkan Wall lizard ( Podarcis quite isolated from other “green areas”. tauricus ) from NM “Mladezhki halm” and Urban areas offer opportunities for NM “Halm na osvoboditelite” in Plovdiv interesting case studies to the ecologists, and present data about the species’ because they are fragmented portions of distribution, habitat selectivity, diurnal and natural and semi-natural zones inside a seasonal activity, abundance, age and sex very anthropogenic influenced area ratio in urban environment. (RUGIERO , 2004). Reptile population responses to urban Material and methods development are perhaps the least The study was conducted between understood in comparison to all other March and October 2007 and 2008 on two vertebrates in urban environments hills (NM “Mladezhki halm” and NM (GERMAINE & WAKELING , 2001). Although “Halm na osvoboditelite”) in the city of ecologists have traditionally paid little Plovdiv (South Bulgaria). attention to ‘urban’ species, much can be Study area. NM “Mladezhki halm” (“The learnt from their populations that inhabit hill of youth”) is situated on 36.2 ha of land urban habitats (DAVIS , 1976). The common (285.5 m a.s.l.) and NM “Halm na species are suitable objects for studying the osvoboditelite” (“The hill of Liberators”) is effects of urbanization, such as, for situated on 22.0 ha of land (265 m a.s.l.). example, some lizard species (JELLINEK et Both nature monuments are situated in the al. , 2004). The Balkan Wall lizard Podarcis centre of the city (Fig. 1) and by origin they tauricus (Pallas, 1814) is one of the most are syenite hills formed during the common lizards in Bulgaria, inhabiting Palaeogene. Both hills are declared for mainly open, dry grassy or rocky habitats protected territories with Regulation № covered by scarce vegetation below 600 m RD466 from 22.12.1995 by Ministry of a.s.l., even anthropogenic terrains Environment and Waters (MOEW), with (BISERKOV et al., 2007). Almost everywhere the aim to protect the natural landscape in the country the species’ populations are and the unique geomorphologic formations dense and numerous (BESHKOV & NANEV , (DIMITROV et al. , 2002). 2002), which makes it suitable indicator Abundance estimates. For calculating the species for studying the effect of abundances of the populations we used a urbanization on its populations. line transect method (SUTHERLAND , 2000). Within the city of Plovdiv there are This method assumes 100% detectability in several “green areas”, besides the urban the center of the line transect, which is parks, of low conservation value, being achievable in fairly open habitats, which heavily visited by people. The hills of are present in the hills of Plovdiv. Eight Plovdiv are green areas which resemble randomly chosen transects (random natural sites, surrounded by heavily samples), each 1000 m long, were made urbanized land (MOLLOV , 2005). Because of through each of the studied areas. 28

Ivelin A. Mollov, Miglena V. Valkanova

Fig. 1. Location of the two urban protected areas within the city of Plovdiv A – NM “Mladezki halm”, B – NM “Halm na osvoboditelite”.

Recording distances were covered by deviations from the normal sex and age means of GPS receiver. The abundance in ratio were compared using the χ 2-test and this case is considered as total number of the tail loss frequency data was compared individuals on the studied area per line using the Mann-Whitney U-test for transect (TURPIE , 1995). independent samples. Both tests are For each observed specimen we suitable when the data is not normally recorded data on date, time, place of distributed (FOWLER et al. , 1998). For the observation and surrounding vegetation. comparison of the abundances we used t- The lizards’ sex was determined based on test with normalized data, using natural the morphological characteristics given by logarithm - ln(x+1) (FOWLER & COHEN , TZANKOV (2007) and BISERKOV et al. (2007). 1995). For statistically significant results we Based on the body size (visually and by considered those with p<0.05 [α=5%]. measuring), we established three age Distribution and spatial data. The groups: adult (male and female), subadult distribution maps were generated from the and juvenile. Data about the condition of collected GPS data for the two-year period, the lizard’s tail (absent or regenerated) was using the “MapSource v. 6.12” software also collected (STRIJBOSCH et al. , 1989). (GARMIN LTD ., 2007) with electronic Data analysis. The statistical processing topographic map “BG Topo Maps v. 2.12” of the data was performed with the (KOTZEV , 2005) and “DIVA-GIS Annapurna software “Statistica v. 7.0” (STAT SOFT INC ., v. 6.0” (ROJAS & HIJMANS , 2008). 2004), using descriptive statistics. The 29

Structure of two populations of the Balkan Wall Lizard Podarcis tauricus …

Results are almost identical, so we are discussing Distribution. The overall distribution of them together. We identified the following both metapopulations of Podarcis tauricus dominant plant taxa: Gleditschia triacantos, for the whole period of study in both study Robinia pseudoacacia, Magnolia denudate, sites is presented in Fig. 2 and Fig. 3. Picea pungens, Criptomeria japonica, Abies Habitat characteristics. At the two study cephalonica and Abies alba from the trees and sites, the Balkan Wall lizard inhabits Crataegus monogyna, Paliurus spina-christi, mainly open rocky areas with short grass- Cornus mas, Prunus spinosa, Rosa canina and shrub vegetation. The habitats on both hills Forsythia suspense from the shrubs.

Table 1. Abundance (individuals/1000 linear meters) of both metapopulations of Podarcis tauricus in Plovdiv for the two-year period. Legend: Mean – mean abundance, CI – confidence interval (95%), SD – standard deviation.

Site 2007 2008 Mean CI SD Mean CI SD NM “Mladezhki halm” 3.12 -0.70÷6.95 4.58 3.00 0.20÷5.79 3.33 NM “Halm na osvoboditelite” 1.87 1.05÷2.70 0.99 0.62 -0.14÷1.39 0.92

Abundance. The abundance of the broken tails and 2.04% with regenerated population at NM “Mladezki halm” is tails and at NM “Halm na osvoboditelite”, higher, compared with the abundance of 15% were with broken tails and 10% with the population at NM “Halm na regenerated tails. osvoboditelite”, but there are no statistically significant differences (t-test, Table 2. Diurnal activity of both p>0.05). There is also a visible pattern of metapopulations of Podarcis tauricus decrease in the population abundances on in Plovdiv for the whole period of study both hills for the two year period (Table 1), but only the population from NM “Halm NM NM “Halm na osvoboditelite” has statistically Time “Mladezhki na osvobo- significant differences (t-test, t=2.57, zones p=0.02). Halm” ditelite” Diurnal and seasonal activity. The Balkan Before 8:00 - - Wall lizard shows a bimodal daily activity 8:00-9:00 1 1 pattern, with one peak in the morning and 9:00-10:00 4 1 second in the afternoon (Table 2). The 10:00-11:00 6 2 seasonal activity also shows a bimodal 11:00-12:00 6 4 activity pattern (Fig. 4) with one peak in 12:00-13:00 4 1 the spring (March-May) and second peak 13:00-14:00 3 - in the autumn (August-September). 14:00-15:00 3 - Escape behaviour and tail loss frequency. 15:00-16:00 4 1 Like other lacertids Podarcis tauricus 16:00-17:00 6 2 exhibits tail autotomy to escape potential 17:00-18:00 6 3 predation. A certain number of the 18:00-19:00 5 2 observed animals were with broken or 19:00-20:00 2 2 regenerated tails – at NM “Mladezki After 20:00 - 1 halm”, 4.08% of the lizards were with 30

Ivelin A. Mollov, Miglena V. Valkanova

Fig. 2. Distribution of Podarcis tauricus at NM “Mladezhki halm”.

Fig. 3. Distribution of Podarcis tauricus at NM “Halm na osvoboditelite”. 31

Structure of two populations of the Balkan Wall Lizard Podarcis tauricus …

Both interpopulational (U-test, U=32.5, Most of the described dominant p=0.81) and intersexual (U-test, U=36.0, vegetation on the hills is not p=0.65) tail-brake frequency differences autochthonous. The indigenous vegetation were not significant (U-test gives in all on both hills consisted of only grass and cases p>0.05), but the population from shrub species (including some endemic “Mladezhki halm” shows the lowest species like Genista rumelica, Hypericum values. The comparison of the tail loss rumelicum, Centaurea affinis ) and almost no frequency between the age groups also trees. In the beginning of the XX century showed not significant differences (χ 2=1.75, and afterwards the indigenous vegetation df=2, p=0.41). was gradually displaced with many Sex and age structure. In both decorative shrub and tree species, used metapopulations, our study shows a sex widely in the gardening and the city parks ratio close to 1:1 with a slightly deviation (DIMITROV et al. , 2002). towards the females (Fig. 5). However, all In nature, the Balkan Wall lizard these deviations from the 1:1 ratio are not inhabits lowlands with scarce vegetation: significant (χ 2-test, df=1, p>0.05). The sex lawns with Amorpha frueticosa and ratio in the population from NM Marsdenia erecta shrubs (KABISCH & “Mladezhki halm” is 1:1.29 (χ 2=0.64, df=1, ENGELMANN , 1970); sand dunes with partly p=0.42) and the sex ration in the quite meagre vegetation, consisting of population from NM “Halm na grasses and Artemisia sp. as dominant plant osvoboditelite” is 1:1.28 (χ 2=0.25, df=1, (NÖLLERT , 1983) in Bulgaria and open p=0.61) towards the females. lowlands with grass-shrub vegetation The age structure in both consisting of Inula sp., Calendula sp., metapopulations is almost identical. The Chrysanthemum sp., Euphorbia sp. and highest percentage is taken by the adults, Trifolium sp. as well as olive groves, followed by the subadults and the cultivated areas, gardens, road sides, juveniles (NM “Mladezki halm”: adult – brambles and fences in Greece 42.86%, subadult – 36.73%, juvenile – (CHONDROPOULOS & LYKAKIS , 1983). Similar 20.41%; NM “Halm na osvoboditelite”: habitats are described by UNDJIAN (2000), adult – 45%, subadult – 35%, juvenile – BESHKOV & NANEV (2002) and SCHLÜCHTER 20%). The deviation of the equal (2006) from other natural sites in Bulgaria. distribution of the age groups (1:1:1) is not The population abundance of Podarcis significant on both hills – NM “Mladezhki tauricus on both urban hills is considerably halm” (χ 2=3.96, df=2, р=0.13) and NM lower, in contrast with natural populations. “Halm na osvoboditelite” (χ 2=1.90, df=2, POPGEORGIEV (2009) reported values from p=0.38). 0.52 to 12.04 ind./1000 m form several populations form the Eastern Rhodopes Discussion Mts. and a value of 12.01 ind./1000 m from Our study indicated that in both study another population form Sakar Mt. sites the lizards inhabit only the interior of We recorded a decrease in the average the hills. At NM “Mladezhki halm” the population abundance for the two-year majority of records came from the southern period. However it is hard to draw any side of the hill in contrast to NM “Halm na conclusions about the populations’ fate, osvoboditelite” where the distribution was due to the short period of study. The lower more homogenic. Apparently the spatial population density at NM “Halm na structure of both metapopulations appears osvoboditelite” could be explained with the to be aggregated (grouped). 32

Ivelin A. Mollov, Miglena V. Valkanova

NM "Mladezhki halm" NM "Halm na osvoboditelite"

number of observations number of 4

h il y ly er a u b apr m june j marc august em october pt se

Fig. 4. Seasonal activity of both metapopulations of Podarcis tauricus in Plovdiv for the whole period of study

56.40% 56.25% 60.00%

43.60% 43.75% 50.00%

40.00%

30.00%

20.00%

10.00%

0.00% NM "Mladezhki halm" NM "Halm na osvoboditelite"

Males Females

Fig. 5. Sex ratio of both metapopulations of Podarcis tauricus in Plovdiv

Structure of two populations of the Balkan Wall Lizard Podarcis tauricus … smaller size of the hill and the higher (usually between males). Unlike other anthropogenic pressure (MOLLOV , 2005). lizards, where the tail loss frequency Perhaps the anthropogenic factor is one of increases with age, Podarcis tauricus doesn’t the main drivers affecting the low follow the same pattern. It seems all age population abundances on both hills due to groups use tail autotomy equally frequent the absence of any strong predation to escape predation. Similar results are pressure (except for some birds of prey and reported by CHONDROPOULOS & LYKAKIS domestic cats) or competition with other (1983) and STRIJBOSCH et al. , (1989) in lizard species (MOLLOV , 2005). Greece. According to our observations, the The normal sex ratio of the natural diurnal and seasonal bimodal pattern of populations of Podarcis tauricus is close to lizard’s activity is more vividly expressed 1:1 as reported by CHONDROPOULOS & in the population of NM “Halm na LYKAKIS (1983) for the majority of the osvoboditelite”, which is probably due to studied natural populations in Greece the different microclimatic conditions. regardless of the sampling season. Even Similar daily activity cycles strongly though the deviation from the normal sex influenced by weather conditions were ratio is not statistically significant, the reported by CHONDROPOULOS & LYKAKIS slight deviation towards the females, (1983) for Podarcis tauricus in Greece, by recorded in our study, may be partly CRUCE (1970) for a natural population in explained with the urban heat island theory Romania and AVERY (1978) for P. muralis (OKE , 1982; CAMILLONI & BARROS , 1997). and P. siculus in Central Italy. In general, The sex determination in reptiles (including many diurnal heliothermic lizards show lizards) is strongly influenced by the similar activity patterns, which are usually temperature of the surrounding determined by climate and weather environment (HARLOW & SHINE , 2006; conditions (PIANKA , 1970; BUSACK , 1976) WARNER & SHINE , 2008). At higher but not by the degree of urbanization in environmental temperatures in the centre particular. of the city, where the studied sites are According to PIANKA (1970), tail loss situated, perhaps more females are frequency of lizards (autotomy) is hatched. correlated directly to predator abundance The age structure showed slight and indirectly to the primary productivity predominance of the adults, with no of the community. Our results could be statistically significant differences between partly explained by Pianka's hypothesis the age groups. The slightly lower due to the fact that the only natural percentage in the juvenile lizards could be predators of Podarcis tauricus on both hills explained with the fact that the juvenile are some birds of prey and the domestic Balkan Wall lizards are very small in size cats, which are more abundant on NM and their coloration matches the “Halm na osvoboditelite”. The absence of environment, which makes them very hard any significant sexual difference in the tail- to spot. So it is possible that the observed break frequencies of the Balkan Wall lizard juvenile lizards were not all present in the may suggest that tail autotomy is used field during the study. On the other hand it equally often by both females and males. is possible that some of the juveniles would We suppose that both sexes are using tail- probably die before they get to the breaking for escaping predator attacks and subadult class thus; there should be fewer it is not attributed to intraspecific fights subadults than juveniles in the population

Ivelin A. Mollov, Miglena V. Valkanova unless individuals stay in the subadult size At NM “Mladezhki halm” the majority of class for more than one year. A stable the records came from the southern side of population can have equal numbers of each the hill in contrast of NM “Halm na age group, more adults, or more juveniles, osvoboditelite”, where the distribution is depending on mortality and fecundity more homogenic. schemes. Unfortunately our results are 2. At the two study sites the Balkan Wall insufficient to determine any certain lizard inhabits mainly open rocky areas population trends. with short grass-shrub vegetation. The In our opinion, in the past the Balkan predominated vegetation on the hills is not Wall lizard was distributed more widely autochthonous was gradually displaced on and around the hills of Plovdiv with with several decorative trees and shrubs, more numerous and dense populations. used widely in the gardening and the city Before the intensive construction that took parks. place around the hills as the city started to 3. The abundance of the populations of grow, there was an abundance of open Podarcis tauricus on both hills is relatively terrains, which this species normally low in comparison to natural sites and inhabits in nature (Fig. 6A.). The rapid varies between the hills and decreased construction around the hills had regularly during the two-year period of study. pushed the lizards towards the interior of 4. The Balkan Wall lizard showed a the hills, fragmenting the species’ bimodal daily activity pattern, with one populations (Fig. 6B). The gradual peak in the morning (between 9:00 and transformation of the habitats on the hills 12:00 am) and second peak in the afternoon during the XX century by introducing of (between 16:00 and 19:00 pm). The seasonal several decorative tree and shrubs activity also showed a bimodal activity additionally influenced the distribution pattern with one peak in the spring (March- and the population’s abundance of Podarcis May) and second peak in the autumn tauricus on the hills of Plovdiv nowadays (August-September). (Fig. 6C). 5. Like other lacertids Podarcis tauricus According to our results and exhibits tail autotomy to escape potential observations the main risks for this species predation. In certain number of the in the city of Plovdiv are construction and observed animals broken or regenerated forestation (destruction of open terrains). tails were observed, but both Nevertheless, it seems that the Balkan Wall interpopulational and intersexual lizard had adapted successfully to the differences were not significant. The remaining suitable habitats in the interior population from “Mladezhki halm” of the hills. The fact that three of the hills of showed the lowest values of tail breaking Plovdiv were declared as protected frequencies. territories had also influenced positively 6. In both metapopulations, our study the survival of this species in the “hostile” showed a sex ratio close to 1:1 with a urban environment. In our opinion Podarcis slightly deviation towards the females tauricus have overcame the risks of (1:1.29). However, all deviations from the urbanization and it should be considered a 1:1 ratio were statistically not significant. very adaptable species. 7. The age structure in both metapopulations was almost identical. The Conclusions highest percentage was shown by the 1. At both study sites the Balkan Wall adults, followed by the subadults and the Lizard inhabits only the interior of the hills. 35

Structure of two populations of the Balkan Wall Lizard Podarcis tauricus …

Figл 6. NM “Mladezhki halm” and NM “Halm na osvoboditelite”: A - a photograph of the two hills made in 1862; B - a photograph of the two hills made somewhere before 1957; C - a photograph of the two hills made in 2008 (explanations are in the text). 36

Ivelin A. Mollov, Miglena V. Valkanova juveniles. The deviation among the age Amphibians and Reptiles of Bulgaria. groups was not significant on both hills. Sofia: Zeleni Balkani. 196 p. (In 8. The main risks for this species in Bulgarian, English summary). the city of Plovdiv are construction and BUSACK S. 1976. Activity Cycles and forestation (destruction of open Body Temperatures of Acanthodactylus terrains). However, Podarcis tauricus erythrurus . - Copeia, 4: 826-830. seems to be well adapted to the urban CAMILLONI I., V. BARROS . 1997. On the environment and at this point not Urban Heat Island Effect particularly threatened. Dependence on Temperature Trends. - Climatic Change, 37: 665–681. Acknowledgements CHONDROPOULOS B., J. LYKAKIS . 1983. The present study is part of the Ecology of the Balkan Wall Lizard, project “MU-1/2008”: "Faunistic and Podarcis taurica ionica (Lacertidae) ecological studies of the amphibians and from Greece. - Copeia, 4: 991-1001. reptiles in the urban environment of the city CRUCE M. 1970. Ciclul de Activitate of Plovdiv" , financed by the Department Sezonier şi Nictemeral la Sopîrla de of Scientific Research (NPD) at the Iarbă ( Lacerta taurica Pallas.). - Studii University of Plovdiv. The authors şi Cercetări de Biologie, Seria Zoologie, would like to express their sincerest 22(5): 467-472. (In Romanian). gratitude to Dr. Liubomir Penev DAVIS B. 1976. Wildlife, Urbanisation (Central Laboratory of General Ecology - and Industry. - Biological BAS), Dr. Iliana Velcheva (University of Conservation, 10: 249–291. Plovdiv, Department of Ecology and DICKMAN C. 1987. Habitat Environmental Conservation), Dr. Fragmentation and Vertebrate Georgi Popgeorgiev (Agricultural Species Richness in an Urban University - Plovdiv) for their notes on Environment. - Journal of Applied the manuscript and Mr. Bogdan Nikolov Ecology, 24: 337–351. (University of Plovdiv, Department of DIMITROV D., M. MIHAILOVA , R. Ecology and Environmental SERBEZOV , K. SANDERS , L. ADJAROVA . Conservation) for his help during the 2002. The Protected Territories in the field work. Plovdiv Region. A Catalog for the Naturalists. Plovdiv: Published by References Foundation “Obshtopolezni proekti”, 80 p. (In Bulgarian). AVERY R. 1978. Activity Patterns, FOWLER J., L. COHEN . 1995. Statistics for Thermoregulation and Food Con- ornithologists. 2ed. BTO,London,150p. sumption in two Sympatric Lizard FOWLER J., L. COHEN , P. JARVIS . 1998. Species ( Podarcis muralis and P. Practical Statistics for Field Biology. sicula ) from Italy. - The Journal of Chichester: John Wiley & Sons. 259 p. Animal Ecology, 47(1): 143-158. GARMIN LTD . 2007. MapSource 6.12. BESHKOV V., K. NANEV . 2002. Computer software [garmin.com]. Amphibians and Reptiles in GERMAINE S., B. WAKELING . 2001. Lizard Bulgaria. Sofia-Moscow: Pensoft. 120 Species Distributions and Habitat p. (In Bulgarian). Occupation along an Urban Gradient BISERKOV V., B. NAUMOV , N. TZANKOV , in Tucson, Arizona, USA. - Biological A. STOYANOV , B. PETROV , D. DOBREV , Conservation, 97: 229 - 237. P. STOEV . 2007. A Field Guide to the

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38 Ivelin A. Mollov, Miglena V. Valkanova

Риск и възможности на урбанизаци-ята характер с два пика – през пролетта и – Структура на две популации на есента. кримския гущер Podarcis tauricus Подобно на повечето същински (Pallas, 1814) в град Пловдив гущери Podarcis tauricus проявява автотомия (самооткъсване) на опаш-ката Ивелин А. Моллов, за да избяга от потенциален хищник. Миглена В. Вълканова Известна част от наблюдава-ните от нас ПУ “П. Хилендарски”, Биологически ф-т, гущери бяха с откъснати или Катедра “Екология и ООС”, ул. „Цар Асен” № регенерирали опашки, но сравняването 24, 4000 Пловдив, [email protected] между двете популации и между двата

Резюме. Настоящото проучване пола не показа статистически значими анализира структурата и някои различия. характеристики на две локални И при двете метапопулации метапопулации на кримския гущер съотношението между двата пола е (Podarcis tauricus ) от ПЗ „Младежки близко до 1:1, с лек превес на женските хълм” и ПЗ „Хълм на освободите-лите” в (1:1.29), като отклоненията от гр. Пловдив. нормалното съотношение не е И при двата хълма кримският гущер статистически достоверно. Възрасто-вата обитава изцяло само вътрешността на структура и при двете показва много хълмовете и не се среща в периферията близки стойности между двете им или извън нея. В ПЗ „Младежки популации, като най-голям процент хълм” се наблюдава леко имат възрастните, следвани от предпочитание на вида към южните субадултните и с най-малък процент склонове на хълма, за разлика от ПЗ ювинилните. „Хълм на освободителите”, където Основните рискове за този вид са разпростра-нението е по-хомогенно. строителството и залесява-нето на И в двете проучвани защитени открити пространства с не-автохтонна територии кримският гущер обитава растителност. Въпреки това изглежда основно открити пространства с ниска вида е добре адаптиран към градска тревисто-храстова растител-ност. среда и не е застрашен от изчезване. Установените доминантни растителни

таксони не са автохтонни за хълмовете, а

са постепенно интродуцирани декоративни дървес-ни и храстови видове. Обилието на метапопулациите на Podarcis tauricus и на двата хълма е сравнително ниска, като по-високи стойности има в ПЗ „Младежки хълм” и като цяло проявява тенденция на намаляване за двугодишния период. Кримският гущер показва бимодал-

на дневна активност с един пик от 9:00

до 12:00 и втори пик от 16:00 до 19:00. Received: 13.06.2009 Сезонната активност на този вид на Accepted: 09.08.2009 Пловдивските хълмове има подобен © Ecologia Balkanica Union of Scientists in Bulgaria – Plovdiv http://eb.bio.uni-plovdiv.bg University of Plovdiv Publishing House