Biologia 66/6: 1177—1182, 2011 Section Zoology DOI: 10.2478/s11756-011-0132-0

Successful restoration of water level and surface area restored migrant populations in a Hungarian

József Gyurácz1, Péter Bánhidi2 & András Csuka1

1Institute of Biology, Savaria Campus, University of West Hungary, Károlyi G. tér 4., Szombathely, H-9700 Hungary; e-mail: [email protected] 2István Chernel Ornithological and Nature Conservation Society, Károlyi G. tér 4., Szombathely, H-9700 Hungary

Abstract: Water level and water surface area fluctuations are important factors determining abundance of bird populations and bird assemblages structure in a wetland . The water level and water surface area of the Marsh T¨om¨ord (West Hungary) changed drastically between 1998 and 2008, and the marsh dried out because of scarce rainfall in 2000 and 2001. A habitat restoration in winter 2001 repaired the waterholding capacity of the marsh. We analyzed changes in parameters of bird assemblages in investigated wetland area in relation of environmental factors. We used full redundancy analysis (RDA) on number of caugth migratory per year, richness, diversity and evenness of bird assemblages to examine correlations among water level, water surface area and vegetation core. Species like water , common snipe, river warbler, Savi’s warbler, , reed warbler, marsh warbler, sedge warbler, reed bunting showed high and positive linear correlations with the water level and water surface area in the postbreeding period. Some wetland species, sedge warbler, Savi’s warbler and reed bunting as well as total number of caugth birds per year and total numbers of caugth species per year were clearly associated with thick marsh vegetation. According to our results the bird species composition of the wetland might have returned to the prerestoration levels and surface areas. Key words: wetland; restoration; bird assemblages; abundance

Introduction and the marsh dried out because of scarce rainfall in 2000 and 2001. The habitat restoration in 2001 repaired Wetland have decreased largely in the last the waterholding capacity of the marsh. More studies decades, and the remaining marsh have been degraded have indicated that water depth, surface (Elphick & to different degrees because of climate change, hu- Oring 1998; Colwell & Taft 2000; Isola et al. 2002), wa- man activities and other factors (Fraser & Keddy ter level fluctuation (O’Neal et al. 2008; Hoover 2009) 2005). Wetland bird assemblages are especially endan- and cover of marsh vegetation are important variables gered because of the increasing frequency of droughts. affecting the use of wetland habitats by wetland birds. Restorated aquatic habitats used as ecological corri- Water depth directly determines the accessibility of for- dors or stepping stones may play an important role in aging and stopover habitats for wetland birds (Darnell the dispersion and stopover of migratory birds (Stan- & Smith 2004). The state of the marsh vegetation and dovár & Primack 2001). The importance of habitat and structure of bird assemblages are determined primar- microhabitat characteristics for bird populations has ily by the quantity and quality of the water (Euliss et been documented for one hundred years (Hejl 1992; al. 2004; Ma et al. 2010). The food supply and vege- Jones 2001). How to provide habitats for wetland birds tation structure of managed affect the species through effective management is a critical issue in bird composition, species diversity and guild-structure of the conservation (Taft et al. 2002). Restoration of wetlands bird communities (Kornan & Adamik 2007). The dif- is a worldwide activity, especially in North America (Er- ferent parts of habitats with a different vegetation con- win & Beck 2007), Northwest (Wolters et al. struction, with a different quality and quantity of food 2005) and Japan (Nakamura et al. 2006). In Hungary source play a different role in the migration of the birds. wetland habitat restoration programs were evaluated in The parts of the habitat with different vegetation has a many cases based on the changes of the bird communi- different effect on the stopover time, migration speed, ties’ (Gáti et al. 2000; Ferenczi et al. 2008). competiton and predation as well as survival chances Many studies have indicated that hydrology is the of the migratory birds (Cody 1985; Berthold & Heil- most important habitat variable determining the wet- big 1992; Gregory et al. 2003). We may make conclu- land structure and functions (Ma 2010). The water level sions from the changes of bird assemblages structure and surface of Marsh T¨om¨ord, a small West Hungarian and abundance of bird species about the ecological state wetland, changed drastically between 1998 and 2008, of stopover sites.

c 2011 Institute of Zoology, Slovak Academy of Sciences 1178 J. Gyurácz et al.

Table 1. Species richness, number of caugth birds per year, diversity and evennes of bird assemblages as well as environmental variables of marsh.

Species Abb. 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 Mean SD

Acrocephalus arundinaceus (L., 1758) AA 0 00001412111.440.25 melanopogon (Temminck, 1823) AM 0 00000100000.620.09 Acrocephalus palustris (Bechstein, 1798) AP 5 11 5 5 10 28 89 29 50 10 50 0.91 1.22 Acrocephalus schoenobaenus (L., 1758) AS 15 28 4 1 5 13 109 20 27 7 60 0.09 0.30 Acrocephalus scirpaceus (Hermann, 1804) AC 4 5223825172341326.5526.82 Alcedo atthis (L., 1758) AT 1 000000101026.2732.07 Anas crecca L., 1758 AR 0 00000001009.648.54 Anas querquedula L., 1758 AQ 0 00000100000.270.47 Emberiza schoeniclus (L., 1758) ES 46 94 79 49 26 44 159 84 151 94 122 0.09 0.30 Gallinago gallinago (L., 1758) GG 0 00001212020.090.30 Gallinula chloropus (L., 1758) GC 0 200002000086.1844.00 Locustella fluviatilis (Wolf, 1810) LF 4 20203942280.730.90 Locustella luscinioides (Savi, 1824) LL 0 00001031330.360.81 Locustella naevia (Boddaert, 1783) LN 7 9 5 22 4 29 25 12 8 8 23 3.27 2.90 Luscinia svecica (L., 1758) LS 0 11001000111.001.34 Lymnocryptes minimus (Br¨unnich, 1764) LM 0 200010010113.829.06 Porzana porzana (Scopoli, 1769) PP 1 100011000000.450.52 aquaticus L., 1758 RA 0 00000412030.450.69 Remiz pendulinus (L., 1758) RP 0 3 11 100000731.182.96 Scolopax rusticola L., 1758 SR 0 00000100000.911.45 Tringa glareola L., 1758 TG 1 00001001102.273.64 Tringa ochropus L., 1758 TO 1 10000151100.090.30

Total number of caugth birds per year TNB 85 159 107 82 48 132 442 178 272 140 290 175.91 116.08 Total number of caugth species per year TNS 10 12 7 7 5 13 15 12 14 13 13 11.00 3.29 Diversity DIV 1.51 1.41 0.99 1.12 1.28 1.77 1.72 1.67 1.43 1.34 1.67 1.44 0.25 Evenness EVE 0.65 0.57 0.51 0.58 0.79 0.69 0.63 0.67 0.54 0.52 0.65 0.62 0.09 Water level (cm) WL 20 10 0 0 50 80 150 140 120 110 120 72.72 58.49 Water surface area (sm) WS 100 100 0 0 200 250 400 350 300 300 350 213.63 143.33 Vegetationcover(A–Dvalues) VC220012444442.4551.63

The monitoring of bird communities and changes and water surface area changed from 0 to 400 m2 between in the composition and abundance of bird species is one 1998–2008 (Table 1), but these two habitat variables were of the greatest traditional research efforts conducted relatively stabile within a post-breeding season. The marsh turned into a mud surface in 1998 and 1999 and to the end of over large spatial and temporal scales in the world and 2 in Hungary as well (May 1975; Báldi et al. 1997; Szép the summer only c. 100 m of water surface remained. The marsh dried out and marsh vegetation was degraded be- 2000; Gregory et al. 2003). Birds are the most inten- cause of scarce rainfall in 2000 and 2001. The reedmace and sively studied in ecology, ethology and con- rush completely disappeared in these years. This was a natu- servation biology, and were studied in many research ral process. We completely removed the peaty bottom of the and environmental management programs (Furness & marsh in winter 2001. From 2002, rainwater started accumu- Greenwood 1993; Lecourret & Genard 1994). lating again in the bed and the marsh vegetation reappeared In this study we examined changes in numbers of in 2003. Water level was highest, and water surface was the caught migrant birds in investigated wetland area in largest in 2004. The abundancy-dominancy (A–D) values of relation of water level, water surface area and marsh reedmace and rush were four between 2004 and 2008 (Ta- vegetation core in the postbreeding period. Our null ble 1). There were three different habitat types around the marsh. These were characterised according to the SE Euro- hypotesis was that the parameters of bird assemblages pean Network (Busse 2000) (see below) as (in this study: number of caugth birds per year, total follows. numbers of caught species per year, diversity, evenness) Forest. Broadleaf trees and bushes made up a compact, and habitat variables (in this study: water level, water dense edge vegetation, forming an ecoton community with surface area and vegetation core) were not linearly re- Turkey oak, wild plum, thorn-bush, wild pear as charac- lated to eachother. teristic plants. There were much fruits and normal forestry management in the forest. The height of vegetation was 6– 7m. Material and methods Bushes. Bushes and herbs made up a compact, dense Study site vegetation, which was dissected by small grass patches. Its Marsh T¨om¨ord is a small (6 ha) permanent and isolated characteristic plants were: wild plum, thorn-bush, wild pear, wetland in West Hungary (47◦2123 N, 16◦4004 E), lo- wild rose. There were much fruits but there was not man- cated 15 kilometres from Szombathely. Characteristic plants agement in the bushes. The height of vegetation was 2–3 m. were reedmace and rush in the marsh. The height of veg- Grassland with scrubs. This habitat type made a transi- etation was 1–2 m. Water was supplied to the marsh only tion between the wet habitats of the swamp and the steppe by precipitation. Water level changed from 0 to 150 cm, communities that used to cover the croplands around the Migrant bird populations in a Hungarian wetland 1179 marsh. There were a few bushes in the grassland, with two Table 2. Results of redundany analysis: eigenvalues and percent- small patches of ground elder. There was not management in ages of inertia. the grassland. The grassland and bushy habitat types were surrounded by a ploughed field in which wheat was grown Axes in 2003. 12 3

Field work Eigenvalue 7.55 1.84 1.07 During the study periods (in August of each year) the water Constrained inertia (%) 72.11 17.61 10.28 level was measured to the nearest 10 cm with a ruler in the Cumulative % 72.11 89.71 100.00 Total inertia 29.04 7.09 4.14 deepest part of the marsh and the water surface area was Cumulative % 29.04 36.13 40.27 estimated to the nearest 50 m2 by air photos. For the regis- tration of the abundancy-dominancy (A–D) values of reed- mace and rush in the marsh the modified Braun-Blanquet scale (0 = no individual, 1 = cover < 5%, 2 = cover 5–15%, 3 = cover 15–25%, 4 = cover > 25% of the marsh area) was Results used in August. The birds were captured and ringed at the T¨om¨ord Richness and diversity Bird Observatory between 1998 and 2008. took We captured 22 wetland species of birds in the place during the post-breeding, from the third decade of July to the first decade of November, 95–100 ringing days study area between 1998–2008. Annual species richness each year. For catching the birds we used 28 numbered mist- ranged from 5 (2002) to 15 (2004). Similarly to species nets (12 m long and 2.5 m high with 5 shelves and a mesh richness, number of caugth birds per year was smallest size of 16 mm). There was a line of six nets in the deepest in 2002 (48 captured birds) and highest in 2004 (442 part of the marsh. Four nets were in the forest, eleven in the captured birds) (Table 1). There was a significant cor- bushes and seven in the grassland. Birds had been captured relation between yearly species richness and number of from dawn to dusk, except on rainy and stormy days. All caugth birds per year (r = 0.86, P < 0.001). birds were ringed and aged according to Svensson (1993) The smallest diversity was in 2000, the highest one and SE European Bird Migration Network protocol (Busse was in 2003 (Table 1). The mean diversity of “dry” 2000). years (H =1.26± 0.21) differed from the mean diver- sity of “wet” years (1.60 ± 0.17) signifcantly (t = 2.86, Data processing and statistical analysis P < We used the number of caugth birds per year of wetland bird 0.05). For species diversity and distribution pat- F P < species in the statistical analysis. To determine bird assem- terns, a significant ( = 1.57, 0.05) and fairly high blages response to change of vegetation core, water level (40.27%) proportion of bird assemblages variability can and water surface area, we calculated species richness (total be explained by the environmental variables tested (wa- numbers of caugth species per year), abundance = num- ter level, water surface are and vegetation core). The ber of caugth birds per year, evenness and species diversity major part of this variability (72.11%) is concentrated for each year. Evenness was calculated as J = H / ln TNS, on the first RDA axes, which has a high linear correla- H where, is Shannon’s index of diversity. Shannon’s diver- tion with habitat (Table 2, Fig. 1). sity for each year was calculated using the formula devel- oped by Shannon and Weiner (Pielou 1975). We compared Abundance the mean diversity of bird assemblages in “dry” years (1998– 2002) and “wet” years (2003–2008) by Student t-test. Linear While wader species and rails were not captured from regression was used to determine the correlation between the 2000 to 2002, waders and rails were more abundant in total numbers of caugth birds per year and total numbers 2004. The grasshopper warbler, sedge warbler, marsh of caugth species per year (Fowler & Cohen 1991). warbler, reed warbler and reed bunting were the five We used full redundancy analysis (RDA) on number most abundant (highest number of caugth birds per of caugth birds per year, total numbers of caught species year) species between 1998–2008. The number of caugth per year as well as diversity and evenness of bird assem- birds per year of marsh warbler, reed warbler, sedge blages to examine correlations among multiple environmen- warbler and reed bunting were highest in 2004, whereas tal factors. RDA allows studying the relationship between the number of caugth birds per year of grasshopper war- two tables of response variables Y (in this study: number of caugth birds per year, total numbers of caught species bler was highest in 2003 the number of caugth birds per per year, diversity, evenness) and explanatory variables X year of marsh warbler, reed warbler, sedge warbler and (in this study: water level, water surface area and vegetation the A–D values of reedmace and rush were smallest in core: abundancy-dominancy values of Reedmace and Rush). 2000 and 2001 (Table 1). In the biplot the vector length and position of the vector- Species like , common snipe, river war- head indicate the correlation between the explanatory vari- bler, Savi’s warbler, great reed warbler, reed warbler, ables and the RDA axes. The significance of the variables marsh warbler, sedge warbler, reed bunting, showed included in the ordinations was determined with permuta- high and positive linear correlations (Table 3) with the tion test (5000 permutations). In this way, we could deter- first RDA axes, indicating that they had a positive as- mine the extent to which environmetal variables influenced bird composition (ter Braak 1992). Statistical analyses were sociation with the water level and water surface area based on software PAST version 1.38 (Hammer et al. 2006) (Fig. 1). Some wetland species (sedge warbler, Savi’s and XLSTAT version 2010.5.07 (XLSTAT version 2010.5.07, warbler, reed bunting) as well as number of caugth birds Copyrigth Addinsoft 2010, http://www.xlstat.com). per year and species richness were clearly associated 1180 J. Gyurácz et al.

Discussion

The different species responded in different ways to the changes of the marsh. Subsequently, species traits and behaviors should be incorporated when analysing bird distribution in wetlands (van Vessem et al. 1997). Species like wetland warblers (Acrocephalus spp.)may be specifically associated with any feature of their habi- tat (Leisler et al. 1989; Pulson 1992). We found some dominant wetland species, for example the reed war- bler, marsh warbler with easily detected strong associ- ations and others, for example sedge warbler and reed bunting with slight associations and the grasshopper warbler with essentially no such associations to water level, surface are and marsh vegetation. The habitat choice of the sedge warbler is narrower in the migration period than in nesting season, because it only takes insects living on the marsh plants to build up fat re- Fig. 1. Redundancy analysis ordination of bird distribution pat- tern over three environmental variables: water level, water surface serves (Ormerod et al. 1991). The habitat preference of area and vegetation cover on the first axes In the full redundancy other wetland birds in a stopover period was similar to analysis, Axes 1 is highly correlated (P < 0.05) with water level, that in the time of breeding (Cramp 1992). The quan- water surface area and vegetation core. The first axes explains tity of the nesting places and the requirement of special 72.11% of the data variability, the second axes 17.60% and the third axes only 10.29%. (See Table 1 for species abbreviations). food restrict the occurrence of the species in the breed- ing period. The fact that several migrants, with their high energy requirements, showed a strong preference for feeding in the habitat with dense marsh vegetation Table 3. Correlation coefficients (bold: permutation test, P < 0.05) between numbers of 22 bird species occurring at study site was possibly the reason for the larger dominance of the and environmental variables resulting from full redundancy anal- sedge warbler, marsh warbler, reed warbler and reed ysis. bunting in the bird assemblage captured after the habi- tat restoration. High abundance of the sedge warbler, Axes reed warbler, marsh warbler, great reed warbler and Species 1 2 3 reed bunting indicated that the best state of the marsh vegetation was in the third year (2004) following the 0.83 Acrocephalus arundinaceus 0.09 –0.29 habitat restoration, when water level and water surface Acrocephalus melanopogon 0.44 0.32 –0.21 Acrocephalus palustris 0.82 0.22 –0.13 were at maximum. More shorebirds fed on the mud- Acrocephalus schoenobaenus 0.64 0.18 0.23 flats following the habitat resstoration, especially jack Acrocephalus scirpaceus 0.88 –0.10 –0.26 snipe, common snipe, Eurasian woodcock, green sand- 0.66 Alcedo atthis 0.24 – 0.222 piper and wood sandpiper. On migration these species Anas crecca 0.30 –0.54 –0.256 Anas querquedula 0.44 0.32 –0.213 characteristically feed on mud- or sand-flats (Cramp & Emberiza schoeniclus 0.71 –0.56 –0.039 Simmons 1983). Gallinago gallinago 0.84 0.08 –0.171 The local changes of annual abundance differed Gallinula chloropus 0.088 0.025 0.634 from the global and Hungarian population trends of Locustella fluviatilis 0.67 0.05 0.277 Locustella luscinioides 0.71 –0.30 0.068 these species between 1998–2008. The grasshopper war- Locustella naevia 0.31 0.47 –0.269 bler, reed warbler and reed bunting breeding popula- Luscinia svecica –0.13 –0.05 0.527 tions showed moderated decline, whereas the others Lymnocryptes minimus –0.01 –0.16 1.011 were stable in Europe (PECBMS 2009). In Hungary, Porzana porzana 0.39 0.32 –0.049 Rallus aquaticus 0.77 0.07 –0.097 the populations trends calculated from the Commom Remiz pendulinus –0.32 –0.44 –0.288 Bird Census database were negative for long-distance Scolopax rusticola 0.44 0.32 –0.213 migrant species and stable or positive for residents, Tringa glareola 0.17 –0.43 0.318 partial migrants and short-distance migrants between Tringa ochropus 0.50 –0.47 –0.191 1999–2005 (Szép & Nagy 2006). Acrocephalus species were the best indicators of wetland habitat and were very rare or absent in the dry years. Their abundance was regulated mostly by water level, water surface area with thick marsh vegetation. In the RDA analysis, the and marsh vegetation. There is also evidence for sev- water level was the most significant environmental fac- eral Palearctic-African migratory species for correla- tor explaining bird distribution patterns (Fig. 1). Of the tion between the size of the breeding population and 22 species, only common kingfisher showed a high and the survival ratio defined by the precipitation on the positive correlation with second RDA axes and none of wintering grounds in (Furness et al. 1993). The them were correlated with third RDA axes (Table 3). favourable or unfavourable climate conditions found on Migrant bird populations in a Hungarian wetland 1181 the stopover and wintering sites show their positive or References negative effects on the mortality rate, so research in these territories should be main task of an international Báldi A., Moskát Cs. & Szép T. 1997. Nemzeti Biodiverzitás- monitorozó Rendszer. IX. Madarak [Hungarian Biodiversity cooperation to protect wetlands of the mediterranean Monitoring System IX. 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