Acrocephalus 2.J (128-129): 13-20, 2006 Population development, nest site selection and conservation measures for White Stork Ciconia ciconia along the lower Tami{ River (Vojvodina, N Serbia) Bela {torklja Ciconia ciconia ob spodnjem toku reke Tami{ (Vojvodina, S Srbija) – populacijski trendi, izbira gnezdi{~ in varstveni ukrepi zanjo Marko Tucakov Marka Ore{kovi}a 9, 25275 Ba~ki Breg, Serbia, e-mail: mtucakov@eunet.yu Number of breeding pairs, their spatial distribution, selection of nest sites and the breeding success of White Stork Ciconia ciconia was studied in 2004 in 20 villages adjacent to the lower Tami{ valley. 322 pairs, which occupied their nests for at least four weeks (HPa) during the first half of the breeding season, were found, 307 of which were HPm: pairs with fledged young. The number of breeding pairs in the 1957 - 2004 period grew in the area, but population in the entire Vojvodina fluctuated. The study area is the most important breeding area for White Stork in the province (30.7% of all breeding pairs) and the country: 27.4% of national population breeds there. One of the most important reasons for the high population density are very suitable feeding conditions. Most of the pairs with fledged young (HPm) had 3 chicks per pair (40.1%), followed by pairs with two chicks (32.5%), four chicks (15.2%), one chick (11.4%) and five chicks (2.4%). The majority of nests were situated on buildings (53.7%) and electric pylons (41.9%). There is a marked change in the breeding habits compared with those in the 1980’s: straw and hay bales have been almost completely abandoned as nest sites since then. Out of the entire number of HPa, 58 (18%) are situated in seven villages adjacent to the first river sector, 213 (66%) in nine villages along the second sector (where the river has wide floodplain) and 51 (16%) in four villages along the third river sector. Key words: White Stork, Ciconia ciconia, population development, Tami{, Serbia, Vojvodina Klju~ne besede: bela {torklja, Ciconia ciconia, razvoj populacije, Tami{, Srbija, Vojvodina 1. Introduction At the national level, White Stork Ciconia ciconia census in Serbia was carried out in 1996. A breeding population of 872 pairs was counted, 93% of them in Vojvodina, indicating the region as the most important for breeding of this species (Pelle 1996). Surveys of breeding pairs of White Stork in Vojvodina have long tradition. Censuses in the province were carried out in 1957 (Szlivka 1959), 1974 (Garovnikov 1977), 1979 (Garovnikov 1980-81) and 2000 (Gergelj et al. 2000). The parameters which were subject of census routine included only total number of active nests (breeding pairs) in particular villages and the nest site selection. Breeding success was surveyed only during the 2000 census (Gergelj et al. 2000). As the last census carried out in 2000 confirmed that one quarter of all pairs breed in villages situated on the edge of the lower Tami{ valley (Gergelj et al. 2000), this region has been subject of survey in 2004. The aim was to determine the number of breeding pairs along the lower Tami{, breeding success and nest site selection. The results of this census are presented and discussed in this paper. I3 M. Tucakov: Population development, nest site selection and conservation measures for White Stork Ciconia ciconia along the lower Tami{ River (Vojvodina, N Serbia) 2. Study area and methods 2.1. Study area The study area was part of the Tami{ River valley, which is situated in Serbia (between 40o50’ N 45o28’ E and 20o23’ N 20o58’ E) in central and southwest Banat (Lazi} 1996). Out of 359 km of this transboundary river, 118 pass through Serbia, between the village of Ja{a Tomi} and the river mouth at Pan~evo (Figure 1). Fluvial erosion and very pronounced fluctuations of the water level, as well as meandering, are the main river’s characteristics. Extremely high water levels are usually recorded in April, extremely low in October (Tomi} 1989). The river regulations started in 1728 and were completed in 1977, when part of the river stretch was included into the Danube-Tisa-Danube hydro system (Tomi} 1989). However, despite the fact that the greater part of the stretch is currently canalized (from the state border downstream to Boto{ (the first sector in the text below) and from Opovo to the river mouth (the third sector in the text below), the river is free-flowing between Boto{ and Opovo (the second sector in the text below) with intensive meandering, preserved river branches (near Farkaždin and Baranda), oxbows (near ^enta), floodplain meadows (near Toma{evac, Uzdin, Farkaždin, ~enta and Boto{) and alluvial forests. Three sectors are different from the hydrological point of view. The first is 33 km long, the second 42 km, the third 43 km (Lazi} 1996). The widest river valley, regularly flooded, follows the boundaries of the second sector. Its widest parts are situated between ^enta and Baranda (10.6 km) and between Orlovat and Uzdin -9.3 km. Five large fishponds are situated in the valley: Sutjeska (900 ha) near Sutjeska, Sveti Nikola (400 ha) at Neuzina, Uzdin (430 ha) near Uzdin, Baranda (1005 ha) between Baranda, Sakule and Opovo, and ^enta (120 ha) near ^enta (Bugar~i} 1999). 2.2. Methods The census was carried out during the breeding season in 2004, from late May to mid August, in particular between 4 Jul and 18 Jul, in the phase of breeding cycle when chicks are visible from the ground, as recommended by the International White Stork Census methodology (Schulz 1999). This allowed simultaneous survey of nest site selection and breeding success. The following data were recorded: nest occupancy, nest site selection (with the following categories: building, electric pylon, tree, straw/hay bales, other) and number of fledged chicks. Only nests occupied by a pair for at least four weeks during the first half of the breeding season are considered to be occupied (Schulz & Thomsen 1999). All nests situated on man-made buildings (houses, churches, observation towers and local power stations) were taken as single category, having in mind that further separation of this category was in many cases impossible. Besides settlements, all other potential breeding areas were surveyed. While counting StDBiol, I took in account surface data for the river valley given by Lazi} (1996). Figure 1: The study area of the lower Tami{ River Slika 1: Raziskovano obmo~je spodnjega toka reke Tami{ 14 ACROCEPHALUS 2.J (128-I29): I3-2O, 200Ć Table 1: Number of breeding pairs of White Stork Ciconia ciconia in villages along the lower Tamiš River in 2004 Tabela 1: Število gnezdečih parov bele štorklje Ciconia ciconia v vaseh vzdolž spodnjega toka reke Tamiš v letu 2004 Naselje HPa HPm Nesting sites / Gnezdi{~a Settlement / Building/ Zgradba Electric pylon/ El. drog 6 Trees/ Drevesa 0 Hay bales/ Bale sena Other niches/ Ostale ni{e Sakule 31 29 24 0 1 Uzdin 30 28 23 4 1 0 2 Boto{ 30 28 0 30 0 0 0 ^enta 28 28 18 9 1 0 0 Idvor 26 25 20 3 2 0 1 Baranda 26 25 24 2 0 0 0 Orlovat 21 17 1 19 0 0 1 Neuzina 21 19 1 20 0 0 0 Opovo 17 17 14 3 0 0 0 Jabuka 13 13 12 0 1 0 0 Boka 12 12 4 8 0 0 0 Toma{evac n 11 1 9 0 0 1 Sefkerin 11 11 11 0 0 0 0 Glogonj 10 10 9 1 0 0 0 Farkaždin 10 9 6 2 0 2 0 Sutjeska 9 9 2 7 0 0 0 Se~anj 7 7 3 4 0 0 0 Ban. Despotovac 4 4 0 4 0 0 0 Ja{a Tomi} 3 3 0 2 0 1 0 Šurjan 2 2 0 2 0 0 0 Total 322 307 173 135 5 3 6 Abbreviations of the breeding parameters follow the methodology of International White Stork Census (Schulz & Thomsen 1999; Table 5 in the appendix). White Stork nests situated on wires of power pylons, as well as birds themselves, can cause a short-circuit, if they complete electric circuit between live and ground wire. Having results of nests site selection from 2004, in order to minimize the conflict and following the best practice in protection of nests situated on the wires (e. g. Perrenou et al. 1996, Mu`ini} 1999), the most problematic nests in the study area placed on overhead wires on electric pylons in 2004 were supported by erection of platforms on top of the pylons before the start of the breeding season in 2005 (between 9 and 30 March). The metal platform was designed in order to create space (70 cm) between the nest and the wires. During the erection process, old nests were taken down from the wires, after which initial layer of branches was fixed at the bottom of the platform on the ground. Then platform was erected and fixed to the pylon top. Nest acceptance was checked between 29 May and 10 Jul 2005. 3. Results In the study area, 360 nests were counted, 322 of which were occupied. Occupied nests were found only in settlements: there were no nests outside them. Nests were found in each of 20 villages bordering the river floodplain (Table 1). Out of all 322 breeding pairs, 58 (18%) were situated in seven villages adjacent to the first river sector, 213 (66%) in nine villages along the second sector, and 51 (16%) in four villages along the third river sector. Breeding success of all breeding pairs (JZa) was 2.58, and 2.60 of all breeding pairs that raised chicks (JZm). Most of the pairs with fledged young (HPm) had 3 chicks per pair (40.1%), followed by pairs with two chicks (32.5%), four chicks (15.2%), one chick (11.4%) and five chicks (2.4%; Table 2). There is no 15 M. Tucakov: Population development, nest site selection and conservation measures for White Stork Ciconia ciconia along the lower Tami{ River (Vojvodina, N Serbia) 3 100% m 90% » 80% S 70% V 60% « 50% ë 40% "S 30% § 20% '¦E 10% I 0% a. 1957 1974 1979 2000 2004 Year / Leto [E other niches ¦ straw or hey bales ¦ tree S electric pylon ¦ building Figure 2: Changes in White Stork Ciconia ciconia nest site selection in the lower Tami{ valley Slika 2: Spremembe v izbiri {torkljinega gnezdi{~a bele {torklje Ciconia ciconia v dolini spodnjega toka reke Tami{ correlation between the pairs’ breeding success within different villages (density groups; Figure 3). The vast majority of nests were situated on buildings (53.7%) and electric pylons (41.9%; Table 1). “Biological” potential density (StDBiol) was 26.9 pairs / 100 km2. The majority of nests on the pylons were situated on the non-isolated wires. Out of 135 these nests in the study area (Table 1), 37 nest-isolation platforms were erected before the beginning of the breeding season, in March 2005. 29 of them (78.3%) were accepted already in that year (Table 4). 4. Discussion The number of breeding pairs in the 1957 - 2004 period grew (Table 3). Despite the fact that in some censuses the coverage of all villages was not complete in the entire valley, the trend is very indicative. However, population in the entire Vojvodina fluctuated in the same period (Szlivka 1959, Čarovnikov 1980-81, Čarovnikov 1977, Pelle 1996). The breeding success (Table 2) was lower than in 2000, when JZm in the same area was 3.38, similar to the whole province where JZm was 3.14 (Gergelj et al. 2000). A possible reason for this is the difference in the level of precipitation between the two years. The year 2000 was the droughtiest in Serbia since the very beginning of weather surveys in Serbia (Republic 16 Hydrometeorological Service of Serbia 2001), while the territory of Vojvodina was extremely wet in 2004 (Republic Hydrometeorological Service of Serbia 2005). Similarly high reproductive success of the White Stork in 2000 was recorded in Switzerland (Boetticher-Streim 1991). It has been proved that the breeding success is in negative correlation with the level of precipitation (Bert & Lorenzi 1999). Absence in correlation of breeding success with density of breeding pairs (Figure 3) opposes the one in the Sava River valley in Croatia, where White Storks breeding in high densities have had higher breeding success, indicating that food resources were evenly distributed and almost unlimited (Schneider-Jacoby 1993). Table 2: Breeding success of White Stork Ciconia ciconia at villages in the lower Tami{ valley in 2004 Tabela 2: Gnezditveni uspeh bele {torklje Ciconia ciconia v vaseh vzdolž spodnjega toka reke Tami{ v letu 2004 Parameter Value/ Vrednost H 360 HPa 322 HPm 307 HB1 16 HB2 6 HPo 16 HPx 33 HPm1 28 HPm2 94 HPm3 116 HPm4 44 HPm5 7 JZG 798 JZa 2.48 JZm 2.60 It is estimated that recently 1000 - 1100 pairs bred in Vojvodina, and 1100 - 1250 in the entire Serbia (Puzovi} et al. 2003), which makes the Tami{ River valley the most important breeding area for White Stork in the province (30.7% of breeding pairs breed there) and the country: 27.4% of the national population breed there. One of the most important reason for such a high population density are very suitable feeding conditions, which are considerably ACROCEPHALUS 2.J (128-I29): I3-2O, 200Ć 4 3.5 3 2.5 2 1.5 1 0.5 0 t' 5 10 15 20 25 30 35 Hpa Figure 3: Correlation between the number of occupied nests of White Stork Ciconia ciconia per village and the breeding success in the lower Tami{ valley (Spearman ? = -0.049, df = 18, NS, two-tailed test, H0 is not rejected) Slika 3: Korelacija med {tevilom zasedenih gnezd na vas in gnezditveni uspeh bele {torklje Ciconia ciconia v dolini spodnjega toka reke Tami{ (Spearman ? = -0.049, df = 18, NS, dvorepi test, H0 ni zavrnjena) more favourable then in other areas in Serbia where regional censuses are conducted (e.g. Ra{ajski 1988, Kuli} 2004). The highest concentration of breeding pairs along the second Tami{ sector is due to the very favourable local feeding conditions in this wide inundation stretch, particularly in the preserved, extensive, temporarily flooded meadow and pastures that follow the river along both banks in this stretch. Findings of Schneider-Jacoby (1993), Eichelmann (1999) and [tumberger & Velevski (2001) also prove that these are optimal foraging habitats for the White Storks and, when covering large areas, they support high breeding densities. These habitats are almost completely missing along the first and the third sectors (own data). It has already been proven that foraging areas during the breeding season in favourable areas Table 3: Development of breeding population of White Stork Ciconia ciconia in the lower Tami{ valley between 1957 and 2004 Tabela 3: Razvoj gnezde~e populacije bele {torklje Ciconia ciconia vzdolž spodnjega toka reke Tami{ med letoma 1957 in 2004 Census year/ Leto popisa HPa Source / Vir 1957 58 SZLIVKA I959 1974 178 Čarovnikov 1977 1979 221 Čarovnikov 1980-81 2000 25O Gergelj et al. 2000 2004 322 this paper are situated in immediate vicinity of nests (OŻgo & Bogucki 1999). All nest sites that White Storks use traditionally in Vojvodina are used in the Tami{ valley as well. However, there is a marked change in the breeding habits compared with those in the 1980s (starting from 1979, as Ra{ajski (1988) describes the situation for S Banat): straw and hay bales have been almost completely abandoned as nest sites since then (Figure 2). The most probable cause for this are changed practices of straw and hay conservation (in stables, under roofs), as well as evident absence of these nesting places in recent years (own data). The same trend was proven for Hungary, but sharp increase of electric pole usage for White Stork breeding started at least one decade earlier then in the Tami{ valley and the entire Vojvodina (Lovászi 1999). Use of trees as nest sites in the study area decreased between 1957 and 2004 as well (Figure 4), although reasons for that are not clear. One of the suggested reasons can be absence of old trees suitable for breeding (A. Žuljevi}, pers. comm.), which happened, for example, in Slovenia (Denac 2001). Numerous concentrated tree-breeding White Stork pairs are site-specific in Vojvodina (Kanjo 2000). Table 4: Results of the White Stork Ciconia ciconia nest-protection program in the lower Tami{ valley in 2005 Tabela 4: Rezultati programa za za{~ito {torkljinih Ciconia ciconia gnezd v dolini spodnjega toka reke Tami{ v letu 2005 Village/ Erected/ Accepted/ Vas Postavljeno Sprejeto Orlovat 10 6 Neuzina 10 9 Botos 8 7 Sutjeska 4 3 Tomasevac 3 2 Sakule 2 2 Acknowledgements: I dedicate this article to my friend David Reeder who is in love in Vojvodinian floodplains and their wildlife and who believes even more than I do that they can and will be sufficiently protected. This study was financed by the Rufford Small Grants for Nature Conservation of The Rufford Maurice Laing Foundation. Many thanks also to Elektrovojvodina Public Enterprise for their professional cooperation in White Stork conservation, to Robert MacCurrach who helped me during survey. Damijan Denac and Slobodan Puzovi} gave useful comments to the manuscript. 17 M. Tucakov: Population development, nest site selection and conservation measures for White Stork Ciconia ciconia along the lower Tami{ River (Vojvodina, N Serbia) 5. Povzetek Leta 2004 je avtor prispevka v 20 vaseh, meje~ih na spodnji tok reke Tami{ v Vojvodini, ugotavljal {tevilo gnezde~ih parov, izbiro gnezdi{~ in gnezditveni uspeh bele {torklje Ciconia ciconia. Zabeleženih je bilo 322 parov, ki so v prvi polovici gnezditvenega obdobja zasedali gnezda najmanj {tiri tedne (HPa), 307 izmed katerih so bili pari s speljanimi mladi~i (HPm). V obdobju 1957 - 2004 je {tevilo gnezde~ih parov v tem obmo~ju naraslo, medtem ko je populacija bele {torklje v celotni Vojvodini nihala. Preu~evano obmo~je je najpomembnej{e gnezditveno obmo~je za belo {torkljo tako v Vojvodini (30,7% vseh parov) kot v celotni državi (27,4% srbske populacije). Eden izmed najpomembnej{ih razlogov za visoko populacijsko gostoto bele {torklje v tem obmo~ju so nadvse ugodne prehranjevalne razmere. Ve~ina parov s speljanimi mladi~i (HPm) je imela po tri mladi~e (40,1%), njim pa so sledili pari s po dvema (32,5%), {tirimi (15,2%), enim (11,4%) in petimi mladi~i (2,4%). Ve~ina gnezd je bila spletenih na stavbah (53,7%) in elektri~nih drogovih (41,9%). Sicer pa so se v precej{nji meri spremenile gnezditvene navade bele {torklje v primerjavi s tistimi v osemdesetih letih prej{njega stoletja: odtlej so bile kot gnezdi{~a skoraj povsem opu{~ene slamnate bale. Od celotnega {tevila parov s speljanimi mladi~i jih 58 (18%) živi v sedmih vaseh, meje~ih na prvi re~ni sektor, 213 (66%) v devetih vaseh vzdolž drugega sektorja (z veliko poplavno ravnico), 51 (16%) pa v {tirih vaseh vzdolž tretjega re~nega sektorja. 6. References Bert, E. & Lorenzi, M.C. (1999): The influence of weather conditions on the reproductive success of the White Stork (Ciconia ciconia) in Piedmont/Italy. pp. 437– 442 In: Schulz, H. (ed.): Weissstorch im Aufwind? – White Storks on the up? Proceedings of International Symposium on the White Stork, Hamburg. – NABU, Bonn. Boetticher-Streim, W. (1991): Der Weissstorch in der Schweiz. – Schweizerische Gesellschaft fur den Weissstorch, Altreu. Bugar~i}, P. (1999): Artificial lakes of Vojvodina – geographical aspects and problems. – PhD thesis, University of Novi Sad, Faculty of Sciences, Institute of Geography, Novi Sad. Denac, D. (2001): Breeding biology, phenology and distribution of White Stork Ciconia ciconia in Slovenia. – Acrocephalus 22 (106–107): 89–103. Garovnikov, B. (1977): White Stork census in Vojvodina in 1974. – Arhiv biolo{kih nauka 29 (1–2): 89–95. Garovnikov, B. (1980-81): Brojnost belih roda (Ciconia ciconia L.) u Vojvodini na osnovu popisa gnezda u 1974. i 1979. godini. – Priroda Vojvodine 6–7: 47–57. 18 Gergelj, J., Puzovi}, S., Ra{ajski, J., Balog, I., Luka~, S., Žuljevi}, A., Tucakov, M., Matovi}, ^., Stojni}, N. & Kova~evi}, B. (2000): Bela roda (Ciconia ciconia) u Vojvodini 2000. godine – populacija i distribucija. – Ciconia 9: 32–44. Kanjo, B. (2000): Gnež|enje bele rode (Ciconia ciconia) u Svilojevu u periodu 1990 – 1999. – Ciconia 9: 187. Kuli}, S. (2004): Promene brojnosti i rasporeda parova bele rode Ciconia ciconia u Leskova~koj kotlini (jugoisto~na Srbija). – Ciconia 13: 114–121. Lazi}, L. (1996): Tami{ river watereconomy problems of Potamisje in Yugoslavia. – PhD Thesis, University of Novi Sad, Faculty of Natural Sciences and Mathematics, Institute of Geography, Novi Sad. Lovászi, P. (1999): Conservation of the White Stork in Hungary. pp. 203–211, In: Schulz, H. (ed.): Weissstorch im Aufwind? – White Storks on the up? Proceedings of International Symposium on the White Stork, Hamburg. – NABU, Bonn. Mu‘ini}, J. (1999): A frame for White Stork nest. – Israel Journal of Zoology 45: 497–499. Ożgo, M. & Bogucki, Z. (1999): Home range and intersexual differences in the foraging habitat use of a White Stork (Ciconia ciconia) breeding pair. pp. 481–492 In: Schulz, H. (ed.): Weissstorch im Aufwind? – White Storks on the up? Proceedings of International Symposium on the White Stork, Hamburg. – NABU, Bonn. Pelle, Z. (1999): Status and biology of White Stork in Yugoslavia. pp. 219–221 In: Schulz, H. (ed.): Weissstorch im Aufwind? – White Storks on the up? Proceedings of International Symposium on the White Stork, Hamburg. – NABU, Bonn. Perennou, C., Sadoul, N., Pineau, O., Johnson, A. & Hafner, H. (1996): Management of nest sites for colonial waterbirds. Tour de Valat, Le Sambuc. Puzovi}, S., Simi}, D., Savelji}, D., Gergelj, J., Tucakov, M., Stojni}, N., Hulo, I., Vizi, O., [}iban, M., Ruži}, M., Vu~anovi}, M. & Jovanovi}, T. (2003): Birds of Serbia and Montenegro – breeding population estimates and trends: 1990 – 2002. – Ciconia 12: 35–120. Ra{ajski, J. (1988): Brojnost gnezde}ih parova belih roda (Ciconia ciconia) sa prate}im pojavama gnež|enja u južnom Banatu za period 1976 – 1985. – Larus 40: 111–123. Republic Hydrometeorological Service of Serbia (2005): Osnovne klimatske karakteristike na teritoriji Srbije u periodu januar-decembar 2004. godine. – Republic Hydrometeorological Service of Serbia. , (Downloaded: 10 Sep 2006) Republic Hydrometeorological Service of Serbia (2001): Padavinski re`im u Srbiji 1961 - 1990. – Republic Hydrometeorological Service of Serbia. , (Downloaded: 10 Sep 2006) Schneider-Jacoby, M. (1993): Vögel als Indikatoren für das ökologische Potential der Saveauen und Möglichkeiten für deren Erhaltung. – PhD Thesis, Biologischen Fakultät, Universität Konstanz. ACROCEPHALUS 2.J (128-I29): I3-2O, 200Ć Schulz, H. & Thomsen, K-M. (1999): Abbreviations, Glossary. pp. 25–26 In: Schulz, H. (ed.): Weissstorch im Aufwind? – White Storks on the up? Proceedings of International Symposium on the White Stork, Hamburg. – NABU, Bonn. Szlivka, L. (1959): Results of the White Stork census in the Vojvodina (Yugoslavia). – Aquila 66: 262–266. Tomi}, P. (1989): Reka Tami{ i njeni vodoprivredni problemi. – Zbornik radova Instituta za geografiju 16: 20–26. Arrived / Prispelo: 6.6.2006 Accepted / Sprejeto: 5.10.2006 I9 M. Tucakov: Population development, nest site selection and conservation measures for White Stork Ciconia ciconia along the lower Tami{ River (Vojvodina, N Serbia) APPENDIX / DODATEK Table 5: Abbreviations of White Stork Ciconia ciconia breeding parameters used in the text (after Schulz & Thomsen 1999) Tabela 5: Okraj{ave za gnezdilne parametre bele {torklje Ciconia ciconia, uporabljene v tekstu (po Schulz & Thomsen 1999) H HPa HPm HPmx HPo HPx HB1 HB2 JZG JZa JZm StDBiol pair which has occupied a nest for at least four weeks during the first half of the breeding season pair with fledged young pair with x fledged young pair without fledged young which has occupied a nest for at least four weeks during the first half of the breeding season pair with unknown breeding success which has occupied a nest for at least four weeks during the first half of the breeding season single bird visiting the nest, no binds to the nest two birds (pair) visiting the nest, no binds to the nest total number of fledged young in a defined area per year breeding success, average number of fledged young per pair related to all HPa of a defined area breeding success, average number of fledged young per pair related to all HPm of a defined area “biological” population density, number of pairs (HPa) per 100 km2 of potential feeding habitat nest 2C