UNIVERZITA PALACKÉHO V OLOMOUCI

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1 UNIVERZITA PALACKÉHO V OLOMOUCI Přírodovědecká fakulta Katedra zoologie Terezie Watzlawiková Vliv urbanizace na ptačí diverzitu v parcích Effects of urbanization on avian diversity in parks Diplomová práce Obor: N1501 zoologie Vedoucí práce: Tomáš Grim Olomouc 2010

2 Terezie WATZLAWIKOVÁ, 2010

3 Prohlášení: Prohlašuji, že předložená diplomová práce je mým původním autorským dílem, které jsem vypracovala samostatně, pod vedením Tomáše Grima. Literární zdroje, z nichž jsem při zpracování čerpala, v práci řádně cituji. V Olomouci

4 Poděkování Předně děkuji vedoucímu práce, Tomášovi Grimovi, za jeho čas věnovaný na konzultacích, cenné rady a pomoc při statistickém zpracování výsledků. Dále děkuji své kolegyni a přítelkyni Evě Chlebkové, za neustálou podporu a rovněž cenné rady. Na závěr děkuji Vilému Pechancovi za jeho pomoc při zpracováním geoinformatických dat.

5 Bibliografická identifikace: Jméno a příjmení autora: Terezie Watzlawiková Název práce: Vliv urbanizace na ptačí diverzitu v parcích Typ práce: Diplomová práce Pracoviště: Katedra zoologie, PřF UP Olomouc Vedoucí práce: Doc. RNDr. Tomáš Grim, Ph.D. Rok obhajoby: 2010 Abstrakt Zabývala jsem se studiem avifauny urbánního a sub urbánního prostředí, konkrétně lokálními a regionálními faktory ovlivňujícími složení a strukturu hnízdních ornitocenóz v městských parcích. Pro analýzu jsem použila rozsáhlý materiál ze sledování ptačích společenstev, které uskutečnil František Hanák na území Moravy a Slezska v České republice. Použitím liniové metody nashromáždil kvalitativní a kvantitativní údaje o složení hnízdních společenstev ptáků 61 parkových zahrad. Provedením mnohonásobné regresní analýzy jsem zjistila pozitivní vliv u proměnných plochy parku a pokryvnosti stromů a keřů na celkovou diverzitu ptáků. Podobné výsledky jsem nalezla také u dutinových hnízdičů. U density ptáků jsem zjistila negativní korelaci s narůstající plochou parku. Naopak pozitivní vliv jsem zaznamenala u pokryvnosti keřů a stromů a vzdálenosti k nejbližšímu lesu. Na závěr jsem testovala vliv jednotlivých proměnných na diverzitu druhů v různém stupni ohrožení. Zde jsem zjistila zejména pozitivní vliv plochy parku a pokryvnosti stromů a keřů a negativní působení narůstající pokryvnosti okolní vegetace. Ostatní lokální (např. věk vegetace, přítomnost vodních ploch) a regionální proměnné (např. vzdálenost k nejbližšímu lesu) nijak nesouvisely s hnízdní avifaunou v parcích. Presentovanými výsledky tato práce rozšiřuje poznatky řady studií avifauny v urbánním prostředí a může být využita pro management parkové zeleně s cílem co nejvíce podpořit avifaunu měst. Klíčová slova: městské parky, avifauna, druhová diverzita, densita, lokální faktory, urbanizace, regionální faktory

6 Bibliographical identification: Author s first name and surname: Terezie Watzlawiková Title: Effects of urbanization on avian diversity in parks Type of thesis: diploma paper Department: Department of Zoology, Palacky University, Olomouc Supervisor: Doc. RNDr. Tomáš Grim, Ph.D. The year of presentation: 2010 Abstract I have studied the avifauna of urban and sub urban environment, specifically local and regional factors which influence the composition and structure of nesting ornithocenoses in the city parks. In order to perform this analysis I have used an extensive data sets resulting from monitoring of bird communities by František Hanák in Moravia and Silesia in the Czech Republic. He utilized a line transect method to collect qualitative and quantitative data about composition of nesting communities of birds in 61 parks. By using multiple regression analysis I have found out a positive influence of park area and coverage of trees and shrubs on total diversity of birds. I have detected similar results in hollow nesting birds. Regarding overall density of birds, I have detected a negative correlation with growing area of a park. On the contrary, I have reported positive impact of coverage of shrubs and trees and the distance to the nearest forest. Finally, I have tested the impact of local and regional variables on diversity of species under various level of threat. Here, I have found out a positive impact of park area and coverage of trees and shrubs and a negative effect of growing coverage of surrounding vegetation. Other local (e.g., vegetation age, presence of water) and regional variables (e.g., distance to the nearest forest) did not covary with the avifauna parameters in parks. The results which I present by this work extend the findings of a number of studies carried out in urban environment and can be used for management of park greens with the objective to support the avifauna in cities as much as possible. Key words: urban parks, avifauna, species diversity, breeding density, local factors, ubranization, regional factors

7 OBSAH: ÚVOD...8 LITERATURA:...10 RUKOPIS ČLÁNKU U...12

8 ÚVOD Urbanizace je v současné době vnímána jako jedna z hlavních příčin, která významně ovlivňuje biodiverzitu v celosvětovém měřítku (Jokimäki a Kaisanlahti Jokimäki 2003). Její vliv se promítá především v narůstající fragmentaci krajiny (Wilcox a Murphy 1985), která souvisí se ztrátou přirozených prostředí (Andrén 1994) a poklesem ptačí druhové rozmanitosti (Jokimäki a Suhonen 1993, Chamberlain et al. 2007). Z těchto příčin je řada druhů ohrožena vymíráním v důsledku silně pozměněných ploch původního prostředí, stoupajícím vlivem okrajového efektu a narůstající izolací od ostatních populací (Ghosh 2003). Uvnitř urbánního prostředí představují parky a zahrady oázy zeleně, ve kterých mnoho druhů ptáků nalézá vhodné útočiště (Fernandez Juricic a Jokimäki 2001). Od přirozeného prostředí se městské parky liší některými důležitými prvky (např. snížená celková vegetační pokryvnost, absence některých vegetačních pater, lidské disturbance) a tím také zásadně ovlivňují ptačí společenstva (Jokimäki 1999). Zejména utváření vegetace a velikost parku jsou označovány za jedny z nejvýznamnějších faktorů formujících městskou avifaunu (Savard et al. 2000, Cornelis a Hermy 2004). Studiem ptačích společenstev uvnitř městské zástavby se zabývala řada autorů (např. Fernandez Juricic 2000, Murgui 2007, Khera 2009, Vallejo et al. 2009). Jejich výsledky napomohly k objasnění otázek vlivu urbanizace na diverzitu avifauny, na distribuci a abundanci jednotlivých druhů ptáků. Několik prací se také zaměřilo na studium vlivu urbanizace v širším měřítku. Prostřednictvím srovnávání městského a okolního prostředí (např. Mason 2006, Palomino a Carrascal 2006) nebo různých měst (Suhonen a Jokimäki 1988, Clergeau et al. 2001) se zjistilo, které lokální nebo regionální faktory mají významný vliv na formování ptačích společenstev. Navíc tyto studie přinesly další poznatky o druhové skladbě ornitocenóz v urbánních oblastech. Jiné výzkumy směřovaly k diskuzi týkající se homogenizace ptačích společenstev (McKinney 2006). Všechny tyto poznatky jsou významné ve vztahu k ochraně biodiverzity a užití vhodného managementu v urbánním prostředí (Savard et al. 2000). 8

9 Většina předešlých prací se zaměřila na studium urbánní avifauny uvnitř jednoho města (např. Chamberlain et al. 2007) nebo naopak v rozsáhlém mezinárodním (např. Thompson et al. 1993) či dokonce mezikontinentálním měřítku (např. Clergeau et al. 2001). V této práci jsem se proto zaměřila na studium ornitocenóz urbánního parkového prostředí v středním měřítku (tj. mezi městy, ale uvnitř jednoho státu), které se zatím jeví prozkoumáno méně než výše uvedená lokální a globální měřítka. V tomto ohledu je velmi důležité, že právě středním měřítko je nejvýznamnější z hlediska ochrany přírody výběr míst pro soustředění ochranářských snah se většinou děje ve středním měřítku, nikoli v tom nejlokálnějším či naopak nejglobálnějším. Konkrétním cílem mé práce bylo zhodnotit, které z vybraných lokálních a regionálních faktorů prostředí významně souvisí s parametry ptačích společenstev v urbánních parcích. Předpokládala jsem pozitivní vliv plochy parku, stáří stromů, pokryvnosti stromů a keřů (uvnitř a v okolí parku) a přítomnosti vody. Naopak u proměnných jako je pokryvnost bylin, nadmořská výška, management, počet obyvatel ve městě a izolovanost jsem očekávala opačný trend. Všechny proměnné jsem testovala v souvislosti s celkovou ptačí diverzitou, denzitou, dutinovými hnízdiči a diverzitou druhů v různém stupni ohrožení. Tato diplomová práce je předkládána jako rukopis odborného článku. 9

10 LITERATURA: Andrén H., 1994: Effects of habitat fragmentation on birds and mammals in landscapes with different proportions of suitable habitat: a review. Oikos 71: Clergeau P., Jokimäki J., Savard J P.L. 2001: Are urban bird communities influenced by the bird diversity of adjacent landscapes? Journal of Applied Ecology 38: Cornelis J., Hermy, M. 2004: Biodiversity relationships in urban and suburban parks in Flanders. Landscape and Urban Planning 69: Fernández Juricic E. 2000: Bird community composition patterns in urban parks of Madrid: the role of age, size, and isolation. Ecological Research 15: Fernández Juricic E., Jokimäki J. 2001: A habitat island approach to conserving birds in urban landscapes: case studies from southern and northern Europe. Biodiversity and Conservation 10: Ghosh P., 2003: Forest fragmentation: A Threat of Global Biodiversity. G.B. Pant Institue of Himalayan Environment and Development, Kosi Katarmal, Almora. Chamberlain D.E., Gough S., Vaughan H., Vickery J.A., Appleton G.F. 2007: Determinants of bird species richness in public green spaces. Bird Study 54: Jokimäki J Occurrence of breeding bird species in urban parks: Effects of park structure and broad scale variables. Urban Ecosystems 3: Jokimäki J., Kaisanlahti Jokimäki M. L. 2003: Spatial similarity of urban bird communities: a multiscale approach. Journal of Biogeography 30: Jokimäki J., Suhonen J. 1993: Effects of urbanization on the breeding bird species richness in Finland: a biogeographical comparison. Ornis Fennica 70: Khera N., Mehta V., Sabata B.C. 2009: Interrelationship of birds and habitat features in urban greenspaces in Delhi, India. Urban forestry and urban greening 8: Mason C.F. 2006: Avian species richness and numbers in the built environment: can new housing developments be good for birds? Biodiversity and Conservation 15: McKinney M.L. 2006: Urbanization as a major cause of biotic homogenization. Biological conservation 127:

11 Murgui E. 2007: Effects of seasonality on the species area relationship: a case study with birds in urban parks. Global Ecology and Biogeography 16: Palomino D., Carrascal, L.M. 2006: Urban influence on birds at a regional scale: A case study with the avifauna of northern Madrid province. Landscape and Urban Planning 77: Savard J. P.L., Clergeau P., Mennechez G. 2000: Biodiversity concepts and urban ecosystems. Landscape and Urban Planning 48: Suhonen J., Jokimäki J. 1988: A biogeographical comparison of the breeding bird species assemblages in twenty Finnish urban parks. Ornis Fennica 65: Thompson P.S., Greenwood J.J.D., Greenway K. 1993: Birds in European gardens in the winter and spring of Bird Study 40: Vallejo B.M., Aloy A.B., Ong P.S. 2009: The distribution, abundance and diversity of birds in Manila s last greenspaces. Landscape and Urban Planning 89: Wilcox B.A., Murphy D.D. 1985: Conservation strategy: The effects of fragmentation on extinction. American Naturalist 125:

12 RUKOPIS ČLÁNKU Explaining avian diversity in urban and rural parks: roles of local and regional factors Watzlawiková Terezie 1, Chlebková Eva 1, Vilém Pechanec 2 & Grim Tomáš 1 * 1 Department of Zoology and Laboratory of Ornithology, Palacký University in Olomouc, tr. Svobody 26, CZ Olomouc, Czech Republic 2 Department of Geoinformatics, Palacký University in Olomouc, tr. Svobody 26, CZ Olomouc, Czech Republic * Author for correspondence: tomas.grim@upol.cz Abstract Avian species richness in urban and non urban park areas is of considerable conservation interest because parks represent important refuges for both birds and other organisms. Here, we tested possible effects of size, local and regional factors on avian species richness (overall, hole nesters, threatened species) and overall cumulative density. Specifically, we also addressed possible effects of levels of urbanization and management intensity. We collated data from long term studies of late F. Hanák. These data show following advantages: were collected by one highly experienced observer, cover large number (60+) of parks that show high variation in explanatory variables of interest and provide accurate estimate of real species richness (all study sites were surveyed for 3 4 years, thus even rare species were unlikely to be missed). We found park area as the most important factor explaining all response variables. Similarly, vegetation characteristics, particularly coverage of trees and shrubs, covaried positively with avian species richness and density. However, we detected no statistical relationships between other local factors (e.g., management, water presence) and parameters of bird communities. Regional factors were important only in relation to bird density and number of threatened species. Bird density increased with increasing distance to nearest forest. 12

13 Threatened species might have been negatively influenced by increasing vegetation coverage outside park. Our study emphasizes the importance of local as opposed to regional factors in moulding avian diversity in urban parks. Key words: urban parks, species richness, local factors, bird density, regional factors, urbanization 13

14 Dedicated to the memory of late František Hanák ( ) Introduction Parks are characteristic and important components of human affected landscapes (Honza 1992, Evans et al. 2009). They provide suitable nest sites, hiding places and food sources for birds and other organisms (Khera 2009). Degradation of natural habitats makes parks important refuges for many taxa (Davis and Glick 1978) and parks are thus viewed as crucial biodiversity conservation areas in urban setting (Khera 2009). However, urban green places differ from the natural ones in many ways (vegetation structure and its taxonomical composition, level of disturbance etc.; Jokimäki 1999). Thus, it is important to understand factors that support species richness and presence of threatened species in both urban and non urban parks (Fernandez Juricic and Jokimäki 2001). Knowledge of those factors needs to be urgently translated into conservation management and urban planning (Nieemelä 1999, Clergeau et al. 2001). The major changes in primary landscape are caused by the process of urbanization, which is negatively correlated with bird species richness and diversity (Wilcox and Murphy 1985, Clergeau et. al 2001, Chamberlain et. al 2007). Landscape fragmentation is linked to loss of habitats, decreased habitat patch size and increased isolation (Andrén 1994). The loss of habitat seems to be more important than fragmentation itself (Fahrig 2002). Effects of urbanization can be studied at various scales from local to intercontinental. Great majority of urban studies so far focused at the smallest possible scale within a single town (e.g., Luniak 1981, Sasvari 1984, Mulerova Frankeova and Kocian 1995, Jokimäki 1999, Sandström et al. 2006, Chamberlain et al. 2007, Murgui 2007, Campbell 2009, Khera 2009, Vallejo 2009). Although these studies might provide important insights into factors moulding local avian diversity in urban areas there is a possible problem with all within one town studies. This is that all habitat patches within a study town can be influenced by some local unique factor or idiosyncratic interaction of various factors that is not representative of factors acting in different towns. In other words, data clustered within one town (or other type of locality) are non independent (see the important issue of pseudoreplication: Hurlbert 1984). 14

15 At the other opposite of the scale, relatively few studies compared avian species richness and community composition between localities in various countries (e.g., Jokimäki et al. 2002) or even continents (e.g., Clergeau et al. 1998, Clergeau et al. 2001). However, these studies compare communities that consist of non overlapping species pools and differ in too many large and small scale factors. Thus, it is inherently hard or outright impossible to disentangle effects of factors responsible for between continent site differences in studied parameters. Moreover, if conclusions of urban habitat studies are to be translated into conservation actions, the large scale studies can hardly be used for this aim conservation action never takes place at continental levels (thus factors operating at continental levels are largely irrelevant for conservation, Orme et al. 2005). Thus, from a practical view (the usage of scientific data for conservation) and a basic research view (an understanding of factors driving diversity in human dominated landscapes) it is obvious that middle landscape level is most important. In comparison to large body of literature on within town urban studies, number of studies on regional landscape level is relatively small (Suhonen and Jokimäki 1988, Jokimäki and Suhonen 1993, Thompson et al. 1993, Jokimäki et al. 1996, Cornelis and Hermy 2004). Further, many of these studies are based on modest sample sizes (~ parks). All studies of avian diversity at the global level are based on long term data, i.e., species richness values for particular grid cells result from data accumulated across many years (e.g., Holmes et al. 1986, Orme et al. 2005). In a striking contrast, almost all studies of urbanization vs. birds are based on data from a single field season (Jokimäki and Suhonen 1993, Jokimäki 1999, Fernandez Juricic 2000, Mason 2006). However, such data might not be well representative of long term avian species richness, e.g., due to nonrepresentative weather conditions in the particular study year or random fluctuations in species density and/or presence in the particular study site. In the present study we aimed to ameliorate these possible problems by including data with larger spatial (parks scattered over the area of more than km 2 ) and temporal coverage (3 or 4 breeding seasons, depending on particular park). We collated these data from long term studies of late F. Hanák (Table 1). His data sets are beneficial because (1) were collected by one highly experienced observer, (2) cover large number 15

16 (60+) of parks that (3) show high variation in explanatory variables of interest (Table 2), (4) cover relatively large geographical area, and (5) provide good estimate of real species richness (all study sites were surveyed for 3 4 years with standard 6 visits per site per year leaving negligible chance of missing any bird species regularly living in any of the studied parks). Such data are clearly more representative and less influenced by the above mentioned confounding factors than data from typical avian urban studies. Further, because of the relative low number of birds breeding in Central Europe these data most likely include all species present in study areas (i.e., it is highly unlikely that even the rarest species would be missed with such an extensive sampling effort). The purpose of the present study was to test possible effects of local and regional factors on selected parameters of bird communities in urban parks. We predicted that species richness, number of cavity nesting species and number of threatened species would increase with increasing park area, vegetation coverage (within and outside parks) and age of trees and decreased with increasing coverage of grass. Further, we expected higher species richness (overall and threatened species) and population density in parks with presence of water bodies. By contrast we expected negative influence of management, isolation (increasing distance to forest or farmland) and urbanization (human population, increasing coverage of buildings or farmland) on avian species richness (overall, hole nesters and threatened species) and bird density. Finally, we predicted that bird density would negatively associate with park area and positively with coverage of trees and shrubs. Methods Study area and bird census The study area was situated in Southern and Eastern part of Czech Republic. All parks were scattered over an area of km 2, 172 km in North South direction and 187 km in West East direction. In the period of F. Hanák thoroughly investigated 62 parks which ranged in size between 0.19 ha to ha (Table 1). Hanák visited parks from April to July and made two visits per month, giving eight censuses per year per park. Most parks (n = 48) were visited for three years, others for 16

17 four years (n = 13) and one park was surveyed only for two years. We analyzed all parks together because number of survey years (entered as a nominal variable) explained no significant variation in species richness in a model controlling for park area (logtransformed, see Table 3) effects (whole model R 2 = 0.67; number of survey years: F 2,58 = 0.61, P = 0.54). This suggests that species richness values from Hanák s studies reflect true species richness in all studied parks. All observations were done only on days when the whether was good (following Šťastný 1974). Hanák followed methods recommended by Šťastný (1974). Hanák used belt transect method, which is a line transect method modification. In each park he determined the length of a line in proportion to particular park area. He walked on the line (at average speed of 1.5 km/h) and recorded all seen and heard birds within 40 m wide belt (i.e., 20 m on each side of the line). To avoid double counting he recorded only birds flying back or aside. In the present study we collated data on parameters of avian communities and characteristics of parks from Hanák s publications (Table 1). We also measured additional variables that enabled us to test possible effects of both local (i.e., within park) and regional variables (i.e., characteristics of surrounding landscapes): Habitat parameters (Tables 1, 2) 1. Geographical coordinates (using Google Earth). 2. Altitude in m above sea level (using Google Earth). 3. Park area (ha) as given in Hanák s publications. 4. Tree age. Data based on dendrologist records provided in Hanák s papers. 5. Vegetation coverage within park. Hanák used Elmen (1967) method to determine all three vegetation coverage (trees, shrubs, grass). This method is based on regular points net. Number of points is determined according to park area. Trees up to 3 m were included into the category of shrubs. The bryophytes, lichens and tree seedlings were included into the category of grass. 6. Water presence. Data on presence/absence of ponds and streams were provided in Hanák s papers. 17

18 7. Vegetation coverage in park surroundings. We used to estimate proportions of areas covered with woodland (trees and shrubs), developed land and farmland (agricultural fields and pastures) within 500 m from park outside edge (following Murgui 2007). 8. Distance to the nearest farmland (m) (following Murgui 2007). 9. Distance to the nearest forest greater than 10 ha (following Murgui 2007). 10. Management of park. We divided parks into two groups according to the level of management: managed (regularly gardening, mowing grass or cutting shrubs etc.) and unmanaged (free holding park). Measures of vegetation coverage outside parks (7) and park isolation (8 9) were performed in JanMap application of the geoinformatics Janitor program ( All distances were calculated as a shortest distance from the edge of the focal park to the edge of nearest agricultural area or forest. Bird community characteristics Hanák provided some characteristics of surveyed avian communities: species richness (total cumulative number of species), density (cumulative number of all individual birds of all avian species per 10 ha) and number of hollow nesters (total number of species breeding in natural hollows). Hollow nesting species included the stock dove (Columba oenas), owls (Strigidae), woodpeckers (Picidae), tits (Paridae), flycatchers (Muscicapidae), redstart (Phoenicurus phoenicurus), treecreepers (Certhiidae), nuthatch (Sitta europaea), and starling (Sturnus vulgaris). We added another characteristic of conservation importance: the number of threatened species for each park. As threatened we considered bird species that are included in Red List of Threatened Species of Czech Republic (Šťastný et al. 2006) and decree of Ministry of the Environment of the Czech Republic n. 395/1992 Coll. We pooled all species from categories: critically endangered (CO), endangered (EN), vulnerable (VU), near threatened (NT), strong threatened (SO) and threatened (O). Category of least concern (LC) was excluded. 18

19 Statistical analyses First, we collated all studies done by F. Hanák. We then excluded all data collected in winter (Hanák 1997a) and also work where data collected by various methods were pooled (Vermouzek and Hanák 2001). Thus, all data we analyzed come from breeding season censuses and all were collected using belt transect method. Because Hanák did not provide species lists in all his papers, sample sizes differ among analyses (62 parks for species richness and density, 49 parks for hole nesters and threatened species diversity). Data on vegetation coverage (grass, shrubs, trees) within parks were not significantly inter correlated (pairwise correlations; all r s = , n = 62, all P = ). However, data on coverage in the parks surroundings were partly intercorrelated. Woodland cover significantly decreased with developed land cover (r s = 0.41, n = 62, P = 0.001) and non significantly with farmland (r s = 0.20, n = 62, P = 0.11). Buildings cover strongly decreased with increasing agricultural farmland cover (r s = 0.72, n = 62, P < ). To avoid multicollinearity we used PCA (Graham 2003). PC1 explained 57.6% of variation in the data and was positively correlated with farmland coverage (r s = 0.89, n = 62, P < ) and negatively with buildings coverage (r s = 0.94, n = 62, P < ). PC2 explained remaining 42.4% of variation in the data and was positively correlated with vegetation coverage (r s = 0.74, n = 62, P < ). Measures of isolation by distance i.e., distance to nearest forest above 10 ha and distance to farmland did not significantly correlate (r s = 0.18, n = 62, P = 0.15). Data on maximum and average ages of trees (from Hanák s papers) were strongly intercorrelated (r s = 0.92, n = 62, P < ). A priori it could be assumed that only maximum vegetation age would affect birds (Poulsen 2002). Thus, we used only maximum tree ages in our analyses. We found no statistically significant relationship between management level and vegetation characteristics within parks. There were no differences in coverages and tree age between non managed and managed parks (t tests, all P > 0.15). Before main analyses, we selected type of species area relationship (Table 3). We tested linear (untransformed species area), exponential (species log area) and approximation of power (log species log area) models and selected the best model 19

20 according to explained variance (R 2, following Murgui 2007). In some cases there was only a small difference in explained variance between two fitted models (see Table 3), thus, we re run our regression models (see below) also for the second best fitting models. Results were qualitatively the same. Then we followed two step procedure of Chamberlain et al. (2007). First, we tested local (i.e., within park) factors. We fitted full models with altitude, park area, age of trees, coverage of trees, shrubs and grass, water presence and management. We used backward elimination of non significant terms to get minimum adequate models for each of four response variables separately: (1) overall species richness, (2) hole nesters species richness, (3) threatened species and (4) overall bird density. Second, we asked whether additional variation is explained when adding regional (i.e., outside park) variables (human population, outside coverage [PC1 and PC2] of vegetation, farmland and buildings, distance to nearest forest > 10 ha and distance to nearest farmland) into the above mentioned minimum adequate models from the local factors analyses. Again, we sequentially removed non significant terms (at conventional α = 0.05) to get the minimal adequate model. We corroborated our results by running GLM with all variables (both local and regional) included in the models from the start. These analyses led to identical final models as the two step procedure of Chamberlain et al. (2007). We checked all models for linearity of effects, normality of errors and homogeneity of variances (following Grafen and Hails 2002) and we found them satisfactory (see, e.g., Fig. 1 4). Results are presented as means ± S.E. Results Species richness Species richness varied between 11 and 76 bird species per park (n = 62 parks). Species richness was best explained by the exponential model whereas power approximation and linear models provided worse fits (Table 3; Fig. 1). Multiple regression models showed that park area and coverage of trees and shrubs were the only significant variables that positively covaried with species richness (Table 4). No other local factors (e.g., 20

21 management, water presence or coverage of grass) influenced avian diversity. Surprisingly, all tested regional factors did not affect overall species richness. Hole nesters Number of cavity nesting birds ranged from 1 to 22 birds per park. Exponential model best explained the relationship between number of hole nesting species and park area (Table 3; Fig. 2). Results supported our prediction that numbers of hole nesters would be positively influenced by area and coverage of trees (Table 4). Variable of tree age was marginally statistically non significant (P > 0.06). Similarly to species richness analysis, regional factors were not important for explaining hole nesting bird s diversity. Threatened species Out of the total number of avian species detected by Hanák (n = 91 species, 49 parks) a total of 28 bird species were included in our threatened category (see Methods). According to the Red List of Czech republic, 5 species belonged to category of endangered species (EN), 11 to category vulnerable (VU) and 8 species to category near threatened (NT). Based on decree of Ministry of the Environment, 12 species belonged to category strongly threatened (SO) and 6 to threatened (O) category. None of species detected by Hanák was ranked as critically endangered. In two parks there were no threatened species. In remaining parks numbers of threatened species ranged from 1 to 18 species per park. Power model explained the most variability of species area relationship for this group (Table 3, Fig. 3). Threatened species were positively associated with park area, coverage of trees and shrubs, but negatively with increasing vegetation coverage outside parks (Table 4). Bird density Bird density greatly varied between 137 and 2911 ex/10 ha across our selection of parks. It was best explained by power model (Table 3; Fig. 4). As predicted, population density was negatively affected by increasing park area. Further, we found that bird density increased with increasing coverage of trees and shrubs. Surprisingly, bird densities also 21

22 positively covaried with distances to nearest forest but the significance of this relationship was just marginal (Table 4). Discussion Species richness As predicted, overall species richness in studied parks was positively influenced by park area and coverage of trees and shrubs. Park area is usually the main factor explaining bird diversity (Jokimäki 1999, Fernandez Juricic 2000, Cornelis and Hermy 2004, Schwartz et al. 2008). Increasing area may represent growing number of different habitats (Schwarzt et. al 2008, Fernandez Juricic and Jokimäki 2001, Chamberlain et al. 2007) and/or greater quantity of suitable sources (Zanette et al. 2000). This may support high number of species with different habitat requirements (Fernandez Juricic and Jokimäki 2001). Small parks may not provide as many habitats as large ones (Chamberlain et al. 2007). Moreover, other factors affecting birds negatively may be more pronounced in smaller than in larger parks smaller parks may suffer from elevated nest predation rates (Jokimäki 1999). Thus, birds usually avoid small parks (Jokimäki 1999, Murgui 2007). Still, small parks can be important stepping stones (Cornelis and Hermy 2004), when birds are moving within urban landscape. For avian conservation there is a need to estimate a suitable size of park area, which should take into account as much bird s habitat and area requirements as possible (Atmar and Patterson 1995, Fernandez Juricic and Jokimäki 2001). Trees and shrubs are essential for birds above all as breeding and food sources, but also as shelters from predators and/or human disturbance (Bellamy et al. 1996, Murgui 2007). Our results show positive correlation between coverage of trees and shrubs and overall species richness which is in line with previous studies (e.g., Jokimäki 1999, Chamberlain et al. 2007). Presence of water in parks may notably increase bird species diversity (Schwartz et al. 2008). However, we did not found any effect of this variable on avian richness. Thus, we assume that area of water would play more important role for birds than water 22

23 presence itself. For example, Storch et al. (2003) found birds distributions to be strongly affected by water area. Our results did not support our prediction of negative influences of management or urbanization. Possible explanation for this counterintuitive result can be that most management practices are focused on herb/grass or shrubs layer. Indeed, grass coverage did not covary with species richness. Additionally, shrubs pruning by gardeners may represent only minor intervention, which does not translate into the total coverage of shrubs in parks. This might be the reason why we found management level to be a nonsignificant factor. Negative effects of urbanization on breeding bird fauna were reported by many studies (e.g., Jokimäki and Suhonen 1993, Blair 1996). However, we did not found urbanization variables (human population, coverage of buildings) important. Urbanization effects could depend on the type of development of town, if it is city with densely builtup area and high human population or city with well gardened structure and low density of people (Palomino and Carrascal 2006). Our studied towns have not so many inhabitants as those in other studies (Jokimäki and Suhonen 1993). Thus, no detected effect of urbanization in the present study might reflect low variability in the number of inhabitants in our selection of localities. Hole nesters Generally, hole nesting birds are ecologically very important group. For example, primary hole nesters provide cavities attractive for other birds or mammals (Morrison and Chapman 2005). In this study, numbers of hole nesting birds were positively correlated with park area and coverage of trees. We expected also positive influence of tree age, because the old trees the higher probability of development of cavities (Sandström et al. 2006). However, in our study samples age of tree was marginally non significant variable. This may be because it is inherently hard to represent tree age as a single number. For example, distributions of individual tree ages are very likely varying across different parks, maximum tree age (that we used in our analyses) may not well reflect overall vegetation 23

24 age etc. In general, we agree with Morrison and Chapman (2005) that absence of woodpeckers in urban places represents a loss of important component of biodiversity. Threatened species Similarly to previous avian community parameters, numbers of threatened species were positively correlated with park area. In addition, we found positive effect of coverage of trees and shrubs on this species group. Some of the threatened species in our sample belong to owls (e.g., Athene noctua), primary hole nesters (e.g., Picus canus, Dendrocopos syriacus) or species with secretive life style (e.g., Gallinula chloropus, Sylvia nisoria). Thus, sufficient coverage of trees and shrubs may support their populations. On the other hand, we found that number of threatened species was negatively influenced by increasing vegetation coverage outside park. However, this relationship should be interpreted with caution because the effect was only marginally significant (Table 4). If real, such relationship could be explained by threatened species preferences for natural nonurban habitats. Alternatively, it may be due to interspecific competition with other, more abundant and more urbanized bird species (Fernandez Juricic and Jokimäki 2001). Apparently, presence of threatened bird species in urban environments indicates important conservation role of urban parks (Cornelis and Hermy 2004, Murgui 2009). Bird density We found that bird density was affected both by local and regional factors. Avian density decreased with increasing park area. This finding is in line with previous work (e.g., Luniak 1981, Suhonen and Jokimäki 1988). Additionally, we detected a positive effect of coverage of trees and shrubs. These vegetation layers provide more sources for birds, such as food, nest places or cover (Thompson et al. 1993, Fernández Juricic and Jokimäki 2001). Upon this reason not only diversity is higher in more vegetated sites, but also density may increase. Another positive effect we found was that of an increasing distance to the nearest forest. Higher distances from forest may be related to increasing influence of urbanization. It is know, that bird density have tendency to rise from periphery to city centre (Hohtola 1978, Jokimäki 1999). Thus, bird communities situated in urban setting 24

25 may have higher densities than those in natural environments (Beissinger and Osborne 1982). Conclusions In this study we evaluated factors that might potentially affect avian communities in urban parks. We paid attention to a range of local and regional factors within a middle scale of parks scattered across various towns within one country, i.e., at the scale where conservation actions typically take place. The results demonstrate that local factors play more important role than regional ones. Specifically, we found park area and coverage of trees and shrubs as the best predictors of bird habitat relationships. Species richness, number of hole nesters and threatened species increased with increasing park area, but overall bird density decreased. Coverage of trees influenced all avian community parameters, whereas coverage of shrubs showed significant effects only in the case of species richness, threatened species and bird density. Interestingly, no other variables, including management levels or water presence, explained significant variation in our data. Thus, based on our results we suggest that to support avian diversity in urban areas most attention should be paid to (1) maintaining areas of parks as large as possible, and (2) keeping tree and shrub coverage as high as possible. Other studies suggest that also presence of water bodies might support avian species richness (Schwartz et al. 2008, Chamberlain et al. 2007). In a contrast, our results do not suggest that typical management practices in urban parks affect birds. This is no surprising when keeping in mind centuries of cohabitation of birds and humans in Central European landscapes. References Andrén H. 1994: Effects of habitat fragmentation on birds and mammals in landscapes with different proportions of suitable habitat: a review. Oikos 71: Atmar W., Patterson B.D. 1995: Nested temperature calculator: a visual basic program, including 294 presence absence matrices. AICS Research, University Park, NM and The Field Museum, Chicago. 25

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