Lifehistory ,population characteristicsand conservation of the Hungarian meadow viper ( Vipera ursiniirakosiensis )

Beáta Ú jvári 1,Zoltán Korsós 1 ,Tamás Péchy 2

1 Department ofZoology, Hungarian Natural HistoryMuseum, Baross u.13,H-1088 Budapest, Hungary e-mail: ujvari@zoo.zoo.nhmus.hu 2 HungarianOrnithological and Nature ConservationSociety, Kö lt" ou.21,H-1121 Budapest, Hungary

Abstract. Duringa continuouspopulation study of Viperaursinii rakosiensis ,79specimens were measured in theŽ eld,between 1993and 1997. Body length and body mass ofsix juveniles were comparedto those of 43 more specimens whichwere keptduring their Ž rst winterin terraria. SigniŽcant differences were foundin favour ofthe juveniles kept in captivity, whereas acomparisonwith earlier data from1953 showed a strongdecline injuvenile body mass. Based onbody size, three age classes couldbe distinguished in the study population. Theannual activity and reproductive cycle ofthe Hungarian meadow viperis describedfor the Ž rst time. A comparisonto other European populations of Orsini ¢sviperrevealed aremarkablyhigher clutch size in Vipera ursiniirakosiensis ,whichis explainedby the larger bodysize offemales inthe particular population.

Introduction

TheHungarian meadow viper ( Viperaursinii rakosiensis Méhely, 1893) is a small- sized( totallength is about 60 cm) lowlandsteppe form ofthe Viperaursinii species group.Since the Viperaursinii speciescomplex is explained in different ways by the modernmorphological and biochemical research results, the systematic status of Vipera ursiniirakosiensis isstillunresolved, and the subspeciŽ c rankcan only be consideredas provisional(V anceaet al., 1985; Joger at al., 1992; Nilson et al., 1993). TheHungarian meadow viper ( Viperaursinii rakosiensis )isone of themost threatened snakesin Europe(Taká cs et al.,1987; Corbett, 1989; Korsó s, 1992). The former distribu- tionof themeadow viper included the easternmost part of Austria, Hungary, Transylvania (Romania),and northern Bulgaria (Dely and Janisch, 1959). Populations today only exist intworegions of Hungary( inthe Great Hungarian Plain between the rivers Danube and Tisza,and in the Hansá g NatureReserve, northwestern corner of the country), from all theother territories it is mostprobably extinct (Korsó s, 1992; Pé chy et al., 1996). Since c KoninklijkeBrill NV ,Leiden,2000 Amphibia-Reptilia21: 267-278 ® 268 Beáta Újvári, Zoltá n Korsós, Tamá s Péchy

1974,the meadow viper has received full legal protection in Hungary where and since thenit has been one of the most strictly protected species. Theoretical nature conserva- tionvalue of onespecimen is 500,000 HUF (ca.1,960 EUR). Parts ofthedistribution area arealso protected; however, most of thisarea is notgovernmental property, which poses greatproblems for conservationto be effectivethrough habitat protection. The animal is listedin the 1996 IUCN RedList of ThreatenedAnimals as “ threatened”, appearson the CITESAppendixI andthe Berne Convention Appendix II. Eventwo recommendations oftheCouncil of Europeemphasise its strict protection in Hungary.It isalso included in theprogrammeof theHungarian National Biodiversity Monitoring System ( Korsós, 1997). Thesensitivity of thissnake to habitatalteration and human disturbance is quite dramatic. Populationsare subject to short term ( coldwinter, high soil water level, etc.) as well as longterm natural threats (isolation, genetic drift, inbreeding, etc.). However, the meadow viperis immediatelyand most signiŽ cantly threatened by humanagricultural activities, like intensivegrazing, burning, machine mowing, etc ( seemore details in Korsó s andFü lö p, 1994;Pé chy et al., 1996). The biologyof theHungarianmeadow viper is poorlyknown, in partdue to itsrarity in nature. Inthe frame oftheconservation program of the Hungarian meadow viper a continuous populationstudy in theKiskunsá g area( southeastof Budapest,Hungary) is beingcarried outsince1993. The goalof thisproject was tocollectas many data as possibleabout the life historyand population characteristics of thisthreatened snake. The program also included apopulationreinforcement experiment with the support of the Hungarian Ministry of Environment( Nechayand Pé chy, 1994), which aimed at the improvement of thesurvival chancesof aselectedpopulation by helpingthe juvenile specimens to get over their Ž rst winterin captivity. Theaim of thispaper is tosummariseresults on theannual activity of thespecies, with acomparisonof data obtained from captivityand from thewild. The age structure, and annualactivity cycle is describedof the selected population, and compared to two other EuropeanAlpine populations of Viperaursinii .

Materialand methods

Altogether,79 meadow vipers (25 males, 48 females, 6 juveniles)were measuredin the Dabas-Gyón studyarea between 1993 and 1997. The typical vegetation of the habitat consistedof awet,closed grassland ( dryingwet meadow = Molinietum)plantcommunity ofuneven structure, characterised by the grass species Moliniacoerulea , Schoenus nigricans, Chrysopogongryllus and Stipa sp.The structure of thevegetation is arranged intomicrolayers, interspaced by tussocksof grassof differentages. The densityof possible preyitems (insects: large-sized orthopterans, and young lizards: Lacertaagilis , L. viridis and Podarcistaurica )isoften high. For moredetails see Ú jvári andKorsó s (1997). Life historyof Viperaursinii rakosiensis 269

Table 1. Numberof captures of V.u.rakosiensis inDabas-Gyó n.

Males Females Juveniles Recaptures

1993 7 5 27 (7)a 1 1994 7 14 14 (1)b 2 1995 11 22 2c 4 1996 – 5 4 1 1997 – 2 2 1 Total 25 48 49 (8) 9 a Bornfrom three females incaptivity; Ž vedied immediately, two during the winter period. Twenty-seven were released inMay1994. b Elevenwere caughtin September 1994, four were bornfrom a female incaptivity. One juvenilefemale died duringthe winter. Fourteen juveniles were released onthe original spot in May 1995. c Caughtin August 1995 and released inMay 1996.

Dataalso originated from apopulationreinforcement program. In autumn 1993 and 1994,gravid females were collectedand kept in terraria until they gave birth. The young were housedin an enclosed part of theZoological Garden, Budapest until the subsequent spring.The furnishingof theterraria imitated natural habitat ( grassand soil were collected ontheoriginal locality), and to minimize the disturbance of theanimals only one person was allowedinto the room during feeding times. To avoid the association of food with humanpresence no record was keptof the exact food consumption of juveniles. Insects (large-sizedorthopterans) and newborn rodents were providedad libitum, i.e. for all neonatesmore food was availablethan they could utilize. These 30 juveniles,together with 13morecaught in theautumnand handled in thesame way during winter, were releasedin goodcondition in Mayof thesubsequent year at the original collecting locality (table 1). Bodyweight and total length at the juveniles maintained in captivity were measured oncein everymonth during the winter.They were alsomeasured at thedate of theirrelease, andthe data were comparedto those by Lányi ( 1957).In the course of ourstudy not all morphologicaldata were consequentlynoted, hence the number of specimensincluded in ananalysis of agivenmorphological character might differ.

Results Bodysize comparison

Changeof body mass andbody length of the meadow viper juveniles during their Ž rst winteris plotted in Ž gures1 and2 (repeatedmeasures of the same specimens on the sameday). For averagebody mass andlength, there were nostatisticaldifferences between neonatefemales ( x¯ = 3.0 g, s = 0.13, x¯ = 150.3 mm, s = 1.56)andmales ( x¯ = 2.9 g, s = 0.35, x¯ = 148.0 mm, s = 2.5).Using regression analysis ( Sutherland,1996) thegrowth rate of the captive specimens showed an allometric relation: for bodymass thecorrelation was exponential( x = month, y = 2.32e0.16x, r 2 = 0.9665, t = 15.19; 270 Beáta Újvári, Zoltá n Korsós, Tamá s Péchy

Figure 1. Bodymass ofjuveniles during winter ( opencircles = specimens keptin terraria; Žlleddots = measured inthe Ž eld,after hibernation).

Table 2. Comparisonof captiveand in situ specimens after theirŽ rst winter( mean ± standarddeviation, sample size).

Bodymass [g] Bodylength [mm] Keptin terraria 15.7 ± 2.97 (18) 287.0 ± 27.88 (18) Measuredin the Ž eld 6.8 ± 1.91 (9) 203.8 ± 28.39 (10)

P < 0.1%, df = 8),whereas for bodylength was linear( x = month, y = 13.16x+ 127.39, r 2 = 0.9701, t = 16.11, P < 0.1%, df = 8).Measurements of thecaptive specimens at thedate of thereleasewere comparedwith those measured in theŽeldin May ( table2; Žg. 1and2: opencircles and Ž lleddots, respectively). The differences signiŽ cant ( bodymass: t = 7.41, P < 0.1%, df = 23;body length: t = 6.64; P < 0.1%, df = 23).The terrarium specimensgained an average8.9 g and84 mm increaseduring the winter. Acomparisonof ourmeasurements on juvenilesborn in with literature data from 1953 (Lányi, 1957) show a conspicuousdifference in juvenilebody size. While the body mass ofthejuveniles forty years ago appeared to be signiŽcantly higher than today ( t = 3.07; P < 1%; df = 23;Ž g.3),their total length was foundto be smallerthough on a lower signiŽcance level ( t = 2.17; P < 5%; df = 25; Ž g. 3).

Age classes

Onthe basis of the body mass-body length ratio as well as the capture-recapture data, threeage groups can clearly be identiŽed in theDabas-Gyó n population(Ž g. 4).The Ž rst Life historyof Viperaursinii rakosiensis 271

Figure 2. Bodylength of juveniles during winter ( opencircles = specimens keptin terraria; Žlleddots = measured inthe Ž eld,after hibernation).

Figure 3. Comparisonof neonatalviper ¢sbodymass andbody length ( opencircles = owndata; Ž lleddots = data fromLá nyi, 1957). groupincludes the newborns and juveniles that have hibernated only once. The members assignedto thesecond group have reached a largerbody mass duringtheir Ž rst summer, hencethis class contains specimens that have survived their Ž rst feedingperiod and a 272 Beáta Újvári, Zoltá n Korsós, Tamá s Péchy

Figure 4. Age groupsbased on body length plotted against body mass (opencircles = female; Žlleddots = males, thethree greydiamonds connected with a blackline represent onespecimen whichwas recaptured). secondhibernation. The vipers assigned to the third class have survived for twoactive and threeoverwintering periods. This last group (aged of the2-3 calendar year) reaches adult sizeand canbe differentiatedfrom theolderindividuals only by bodymass. The rest of the adultscomprises all individuals with more than 60 gand450 mm, and cannot be reliably splitinto further age groups. Onespecimen was caughtas neonate in September ( Žg.4), kept and fed in captivity duringthe winter, released in the subsequent spring, then recaptured in the summer of thesame year. Its bodymass was duplicated,hence it “ jumped”into the third age class. Thiswas theonly recapture from thejuveniles released in the population reinforcement program. Malesin the Dabas-Gyó n populationwere considerablysmaller than females, and the populationwas dominatedby ahighnumber of oldfemales ( Žg.4).

Annualactivity pattern

Thecaptureand observation data have been analysed and annual activity drawn up ontheir basis.Males, females, and even juveniles emerged from thehibernation together in late March.Mating took place in theŽ rst halfof May,parturition at the end of July,August, orbeginning of September, depending on the weather .Hibernationbegan in the middle ofOctober,but specimens were occasionallyobserved even in November,although their movementswere virtuallystopped, and they only went to bask occasionally to thesurface atthespot of hibernation(Ú jvári andKorsó s, 1999). Life historyof Viperaursinii rakosiensis 273

Discussion

Bodysize comparison

Juvenilemales and females did not differ in theirbody size at birth,which is inaccordance withviviparous snake species ( Viperaberus ,Völkl, 1989; Coronellaaustriaca , Luiselli etal., 1996). In C.austriaca theindividual body size variation was retainedeven 12 monthsafter birth (Luiselli et al., 1996). In ourstudy the larger body size advantage of the specimenskept in terrariacompared to thejuveniles hibernating in natural circumstances was dueto the artiŽ cial ad libitum feeding conditions. Juvenile snakes may beneŽ t from theirlarger body size, by being less susceptible to predation, or may enjoying a higher foragingsuccess (Vö lkl, 1989; Biella and Vö lkl, 1993; Forsman and Lindell, 1996). This mayhelp to increase the survival chances of this meadow viper population. Although it isanunveriŽ ed beliefthat juveniles suffer from highmortality during their Ž rst winter,it canbe clearlyaccepted that body size is astrongdeterminant of juvenilesurvival success (Völkl, 1989; Forsman and Lindell, 1996). The survivalof neonatesduring the Ž rst winter dependson thegrowth after birth too, as shown by Völkl (1989)inthe case of V. berus. He foundthat an increaseof 25%over birth weight was requiredfor asuccessfulhibernation. Thecomparison of ourmeasurements on juvenilesborn in terraria with literature data from 1953(Lá nyi, 1957) showed a conspicuousdifference in juvenile body size. This phenomenonmay be explainedby thedifferent body condition of females,or byunknown environmentalfactors. Regarding the Ž rst,it iswidely accepted that the reproductiveoutput ofmature females increases with body size (Saint Girons and Naulleau, 1981; Blem, 1982;Farrell et al., 1995; Luiselli et al., 1996). Litter size and clutch mass were usually foundsigniŽ cantly correlated with female snout-vent length (André n andNilson, 1983; Farrellet al., 1995, Luiselli et al.,1996), although Saint Girons and Naulleau (1981) found norelationship between the body weight values of offspring and their mothers in some Europeanvipers. Thenumber of neonatesof V.ursiniirakosiensis isremarkably higher than that of their Alpinerelatives ( Viperaursinii ursinii )(Baron,1997), whereas the body length is only slightlylonger in the Dabas-Gyó n population( table3). Regarding body mass, the low valuesdominate, except for thedata of Lányi ( 1957). Consideringreproductive success in Europeanvipers, Saint Girons and Naulleau ( 1981) observethat the difference among species depends not only upon the size of theparents, butalso upon the feeding habits and feeding success of juveniles. Species consuming mainlyinvertebrates (grasshoppers) and lizards produce more numerous but smaller sized offspring,whereas those eating small mammals have smaller clutches of largerjuveniles. Whilethe Ž rst caseis true for Viperaursinii ,thelatter concerns e.g. Viperaberus and Viperaaspis . Within the Viperaursinii speciescomplex, on the other hand, the larger Hungarianmeadow viper have more numerous but smaller hatchlings than the nominal Alpinesubspecies with smaller body size. 274 Beáta Újvári, Zoltá n Korsós, Tamá s Péchy ) ) 1 6 8 ) 9 ) 9 0 s 9 7 1 9 n 1 ( a 5 9 o t ( e 9 r 1 a u . c i l 1 ( a r d ( a i G e u l l i n t l o t l y e e n u S w i n s a o n i á a u o N S L r L a d n B a , s e r u L e e y r d c a n s g a e y y r n r l n F u a a g t , g y a I H t e t x n i , , c l n u u o n n a o o z a t ó c H r z y n o , M u F e a , L r G s - V x b c - s u t a A Ó o n t b o a n e D M V - t n o . ) M e z i s e l ) p ] ) ) ) 6 ) 1 6 8 m m 1 1 5 5 a 2 ( s ( ( ( ( m [ 3 , a 6 7 9 . 0 n 0 h 7 7 . t 6 . . o 2 8 i 0 0 g t 1 n - ± a ± i e 8 ± ± l 2 v 1 5 e 8 3 4 y 2 1 . . . d . d 3 6 6 5 o d 4 3 3 » 3 r 1 1 1 B 1 a d n a t s ) ) ) ± ) ] 6 6 5 9 g 1 2 2 n ( ) [ ( ( ( a 5 6 e s 4 7 4 ( 3 s . 4 4 3 m 3 a . . . . ( 0 0 0 0 2 m e - ± p y ± ± ± 1 . o d 8 r 3 4 8 2 o 7 u . 0 7 9 . . . B 2 E 5 2 2 n i s r e p ) ) i 2 1 v ) 1 9 3 s e ( ( ¢ ( i z ) 1 i 3 3 n . s 2 i 5 1 3 ( s 7 . . r h - 1 0 1 c 5 ± O t ; u ± ± . l 3 4 l r . a 3 3 e t 1 C a 8 0 p 1 . . a n 3 4 p o e e n h t f o n i n s s i i h o s s s p i n n a r e e r i i i i i a i i i g s s p n n n o o i i i a m k k s s s r r r o a a m s r r u u u C e o . . . . . i r . u u u u u c f 3 e a a a a a d p e r r r r r a l s e e e e e e b b p p p p p a u i i i i i R T S V V V V V a Life historyof Viperaursinii rakosiensis 275

Ageclasses and annual activity pattern

From therecapture data we concludethat the age groups are deŽ ned by theactive feeding periodduring summer. The Ž rst ageclass includes hence the neonatals from theend of summerand the same indviduals after their Ž rst hibernation( theypractically do notgrow duringthe winter).Exact age of malesin the third and of femalesin thefourth class cannot beestimatedusing only body mass orbodylength measurements. Thephenomenon that the Dabas-Gyó n populationis dominated by a highnumber of oldfemales may have an advantage in the larger clutch size produced by old females, becauselarge females exhibit a higherratio of reproductiveactivity ( Burkett,1966). They aregravid also more frequently than smaller ones, which parallels data relative to alpine adders Viperaberus (Capulaand Luiselli, 1994). However, this estimate may be biasedif reproductivefemales modify their behaviour (Luiselli et al.,1996), e.g. if theybask in such awaythat they are easier to observe.Gravid females of Viperaursinii ursinii oftengather onsunnyspots of thehillside (Baron,1997). Usually large ( orold) malesare more difŽ cult toŽnd,except in themating season when they move around to lookfor thefemales. Comparingthe annual activity cycle of the Hungarian meadow viper to two Alpine Viperaursinii ursinii populationsin Mont V entoux,France (Baron et al., 1996; Baron, 1997)and in Abruzzo, Italy (Luiselli, 1990) some difference was found.According to theobservations by Baron(1997), females of V.u.ursinii onMontV entouxemerge from hibernationlater than males, at the beginning of May,and juveniles come out almost one monthlater, when appropriately sized (over 16 mm) foodsupply is abundant.In certain Centraland Northern European populations of Viperaberus ,malesemerge earlier than females,too, for completingspermatogenesis (Biella and Vö lkl, 1993). Contrary to the Frenchpopulation, Hungarian and Italian males, females, and even juveniles emerge from thehibernation together, which is similarto some populations of Viperaberus (Viitanen, 1967;Prestt,1971; Nilson,1980) and Viperaaspis (Duguy,1958). In the caseof Hungarian vipersthis phenomenon could be explained by the fact that food for themis provided inhigh abundance of crickets ( Grylluscampestris )overwinteringas adult-sized larvae. Thelonger active period found for bothfemales, males and juveniles (7 months in the Hungarianand Italian populations, 5-6-3,5 in theFrench population) can be aconsequence ofthegeographical and climatic differences. Thereproductive cycle of viviparous viperids in the temperate region is generally consideredto be biennial(Aldridge, 1979; Tegelströ m andHö ggren, 1994; Hö ggren and Tegelström, 1995,1996), although there is discussion about it basedon observationsthat approximately50% of mature females in a givenpopulation reproduce yearly ( Blem, 1982).However, according to Luiselli (1990), Baron et al. (1996), and Baron (1997) Orsini¢sviperalso has a biennialreproductive cycle. Although the females mate every year,fecundation takes place only when body conditions are appropriate ( usuallyevery secondyear). The same phenomenon has been described also in otherEuropean snakes, in Viperaberus (Luiselli,1993, 1995), Coluberviridi avus and Elaphelongissima (Capula 276 Beáta Újvári, Zoltá n Korsós, Tamá s Péchy etal., 1995), and may have crucial consequences for snakereproductive systems ( Capula andLuiselli, 1997). One clutch may hence originate from differentmales. The number of neonatalsis usuallybetween Ž veand twelve. Larger clutch sizes ( e.g.19) are quite rare, andmay be dueto geneticdiversion (Janisch, 1993). Timing of thedifferent events of the annualreproductive cycle of Europeanvipers may vary according to weather conditions, and,to alesserextent, habitat structure ( SaintGirons, 1992).

Conservationaspects

Theresultsobtained thus far revealthat the monitoredpopulation is healthyand capable of survivingin casethe environmental conditions remain unchanged. Although the meadow itselfis state property and has supported the largest known Viperaursinii rakosiensis populationin the world, it is still not ofŽ cially protected. Localised Ž res resultingfrom NATOexcercisesin the past were followedby a hugeŽ re causedby a familytrying to lighta shellin 1997. Dueto an apparent misunderstanding, another area of habitathas since beenshort mown. With better managing this habitat could regain its original plant cover, butthe effectson theHungarianmeadow viper need to be monitoredclosely. Unfortunately, conservationmeasures are usually not based on long-term ecological research, and a venomoussnake has low priority when other nature conservation values in the habitat areconsidered (plants and birds, for instance).Habitat protection is oftenin conict with theinterests of localfarmers, militarytraining, or ecotourism.A populationreinforcement programlaunched as animmediate protection measure has proved useless in threeyears ¢ practice.As aconsequenceof all of these facts, according to a continuousmonitoring since1984, the populations of the Hungarian meadow viper are in constant decline, and facingan immediate risk of extinction.All these results indicate that scientiŽ c researchhas providednature conservation with a betterknowledge for amoreeffective protection and positiveproposals for theoptimalmanagement of thehabitat available, so a moreeffective implementationof natureconservation measures would be possible.An Action Plan is to bepresentedas the framework for futureresearch and nature conservation activities. The proposalfor theten-yearproject is aimedat a complexprotection of thevipertogether with itshabitat on thehighest priority with a scientiŽcally sound research background.

Acknowledgements. We are gratefulDr. Gyö rgy Lá nyi (Budapest) for making available his unpublished results andnotes to this contribution. Many thanks are dueto Istvá n Czuczor (ZoologicalGarden, Budapest) who carefullyhelped to keep the juvenile vipers during the winter. Thanks to Dr. W olfgangVö lkl, Dr. Luca Luiselliand ananonymous referee forcommenting on themanuscript. The project was supportedby the Hungarian National Research Fund(Nos T16608 and F23454), and the permits towork with this protected species were providedby theDirectorate ofthe Kiskunsá g NationalPark (Nos 546-2/ 96,451-2/ 97,451-3/ 97,411-2/ 98),and the Budapest Nature ProtectionAuthority ( BTI-938/2/97). Life historyof Viperaursinii rakosiensis 277

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Received: March31, 1999. Accepted: March6, 2000.