ORIGINAL ARTICLE

Ziemowit Kosinski Æ Aleksander Winiecki

Factors affecting the density of the middle spotted woodpeckerDendrocopos medius: a macrohabitat approach

Received: 12 October 2004 / Revised: 1 February 2005 / Accepted: 24 February 2005 / Published online: 25 May 2005� Dt. Ornithologen-Gesellschaft e.V. 2005

Abstract The main goals of this study were to investigatethe relationships between densities of the breeding pop-ulation of the middle spotted woodpecker Dendrocoposmedius obtained on 19 large-scale plots, and the share ofdifferent habitats and age of forest stands. An averagecrude density based on an area defined arbitrarily byobservers was 0.66±0.43 territories/10 ha, while theecological density based on an area including habitatspotentially used by organisms reached 1.09±0.64 terri-tories/10 ha. Stepwise multiple regression indicated thatthe crude density was negatively affected by the share ofconiferous forest thereby explaining 50% of variation.The ecological density was negatively correlated with thepercentage of young deciduous stands (0–40 years old).This variable explained 36% of the total variation. Theseresults suggest that on the level of macrohabitat analysis,the share of unsuitable forest stands seem to play a majorrole in determining the density of the middle spottedwoodpecker.

Keywords Density Æ Forest age Æ Habitat selection ÆMiddle spotted woodpecker Æ Plot size effect

Introduction

The middle spotted woodpecker Dendrocopos medius is aresident bird species of the Western Palearctic, inhabit-ing mature deciduous forests with rough-barked treespecies, mainly oaks (recent review in Pasinelli 2003).The populations of the species have decreased markedlyin many parts of Europe resulting from changes in for-

estry management and, consequently, a deterioration ofmany middle spotted woodpecker habitats (Mikusinskiand Angelstam 1997; Buhlmann et al. 2003), although inthe northern part of central Europe it is expanding andincreasing in numbers (del Hoyo et al. 2002). Because ofits habitat requirements and foraging ecology, mainlygleaning and probing for bark-dwelling arthropods, themiddle spotted woodpecker is considered to be a habitatspecialist and may therefore be useful as an indicator ofthe quality of an oak-dominated forest (Muller 1982;Buhlmann and Pasinelli 1996; Pasinelli 2000). Ecologicalfeatures have led the middle spotted woodpecker to bedesignated as one of the suite of ‘‘focal species’’, whosehabitat requirements encompass those of all other spe-cies in the landscape (Lambeck 1997; Angelstam et al.2004). Thus, an important step in developing conserva-tion strategies for this species should consist of identi-fying factors affecting the density of populations indifferent scales.

The habitat selection of birds is a hierarchical deci-sion process that starts from landscape scales andproceeds to fine-scale local habitat characteristics (Hil-den 1965) and, in consequence, can be investigated invarious spatial scales (e.g. Gutzwiller and Anderson1987; Rolstad et al. 2000). Earlier macrohabitat anal-yses have suggested that the breeding density of themiddle spotted woodpecker is affected mainly by thehabitat quality and type (Spitznagel 1990), forest sizeand isolation of suitable habitats (Muller 1982; Pet-tersson 1985; Kosenko and Kaygorodova 2001), pro-portion or density of old oaks (Muller 1982; Schmitz1993) and oak volume (Buchlmann and Pasinelli 1996).However, none of these studies have quantified therelationship of density to forest types (deciduous vsconiferous) or the age of forest stands (see review inPasinelli 2003).

The aim of this study was to investigate the densitiesof the breeding population based on large-scale surveys,as well as the relationships between densities and theproportion of different forest stands, including the age ofdeciduous stands.

Communicated by F. Bairlein

Z. Kosinski (&) Æ A. WinieckiInstitute of Environmental Biology,Department of Avian Biology and Ecology,Adam Mickiewicz University, Umultowska 89,61-614 Poznan, PolandE-mail: zkosinsk@main.amu.edu.pl

J Ornithol (2005) 146: 263–270DOI 10.1007/s10336-005-0088-3

Methods

The study was carried out in the Wielkopolska regionsituated in the central part of western Poland, betweenPomerania in the north and Lower Silesia in the south.The analysis was based on the data obtained from 19study plots (range 72–889 ha), collected between 2000and 2003, with a total area of 7,250 ha (see Appendix).The study areas were distributed unevenly throughoutthe region (Fig. 1). Most plots were established in thecentral part along the Warta river valley. All of thempredominantly consisted of deciduous, mainly oak-dominated stands (see Appendix). The dedicatedobservers and professional ornithologists, in compli-ance with the instructions received, chose individualplots. In one case (plot Miłosław), a previously largestudy area (2,000 ha) was divided into three smallerplots (Miłosław I–III, see Appendix), mainly based onhomogeneity of habitat types, to minimise the effect of

the density–area relationship (Scherner 1981; Gastonet al. 1999).

The survey was based on the playback method whichhas been recommended for woodpecker censuses as away of overcoming difficulties in detection and mapping(e.g. Sudbeck and Gall 1993; Kosinski and Winiecki2003; Kosinski et al. 2004) and is widely used in fieldstudies of different woodpecker species (e.g. Wesołowski1995; Fernandez and Azkona 1996; Miranda and Pasi-nelli 2001). The playback method is based on the terri-tory mapping technique, where all contacts with birds,either by sight or sound, are plotted on large-scale maps(Tomiałojc 1980; Bibby et al. 2000). In this way, thenumber of birds holding territory in the study plot canbe assessed. This makes it possible to assess the popu-lation size over large areas (e.g. Becker and Heyne 1994;Noah 2000; Randler 2000; Kosinski and Winiecki 2003),and with high efficiency. It has been documented that upto 80–90% of all territories can be found during one visit(Conrads and Conrads 1992; Gunther 1992; Kosinski

Fig. 1 Distribution of studyplots across the Wielkopolskaregion. For details, seeAppendix

264

et al. 2004). Such a degree of efficiency should be suffi-ciently adequate for large-scale analysis.

The field procedure was standardised to assure thedata comparability among all observers. The studiescovered the peak of vocal and territorial activity of birdsduring the pre-breeding period (March–April) connectedwith establishing and defending territories and mates(Pasinelli 2001; Kosinski and Winiecki 2003). To in-crease the accuracy of the method, special attention waspaid to register simultaneously active birds, in particularthe advertising-call of males (Tomiałojc 1980). To pro-voke responses of territorial birds, taped calls (adver-tising- and rattle-calls) were played every 150–200 m forperiods of 30–40 s (Gunther 1992; Kosinski et al. 2004).After the first bird response, the taped calls were stoppedto determine the initial location of the bird. In this way,the potential effect of attracting individuals away fromtheir territories was restricted (Johnson et al. 1981). Theposition, behaviour (spontaneous or response to the tapecalls), type of call and number of birds recorded (singleor pair) were plotted onto the forest maps (1:10,000;frequently enlarged). In the case of repeated visits (1–4,see Appendix) to the study area, the number of territo-ries was estimated on the basis of all censuses.

Some territories of the species may have been occu-pied by ‘‘unpaired’’ or ‘‘floater’’ birds (Schmitz 1993;Pasinelli 2001; Robles and Olea 2003; own data) whosepresence could not be recognised during standard cen-suses. Thus, the densities are reported as territories/10 ha. Because the number of territories in some studyplots were expressed as range, the lower values were usedduring further analyses.

Two measures of density were calculated: (1) crudedensity, based on an area defined arbitrarily by eachobserver, and (2) ecological density, based on an area ofpotential habitat that the species use (Gaston et al. 1999).It is well known that the middle spotted woodpecker is aspecies inhabiting mature oak-dominated forests. How-ever, it was found breeding in younger stands (ownunpublished data) and in other deciduous forests (seereview in Pasinelli 2003). In consequence, it was assumedthat all deciduous stands should be treated as potentialhabitat of this species. In the first step, an assessment wasmade of the effect of proportion of three types of habitat(see Appendix): area of deciduous stands (DS), area ofconiferous stands (CS) and area of open areas (OA; e.g.clear-cuts, division-lines, roads and waters), extractedfrom the official inventory and management plans ormaps, on crude density, as a dependent variable. Thesmall proportion of unidentified areas (UA) that werenot described on forest maps (average 1% of total area,see Appendix) was omitted in the analysis. During thesecond step, we assessed the effect of age classes ofdeciduous stands on ecological density. However,smooth-barked deciduous forests, such as beech Fagusand hornbeam Carpinus woods, are considered to beunsuitable for this species except in the stage of decay(see Gunther and Hellmann 1997), so the smooth-barkedstands were separated from other deciduous forests. The

rough-barked forests were divided into four age classes:young ( £ 40 years old), middle (41–80 years old), old(81–120 years old) and very old (>120 years old) (seealso Buhlmann and Pasinelli 1996). The smooth-barkedstands were separated into two age categories: £ 120years old and >120 years old (see Appendix). The shareof different forest stands was assessed on the basis ofdominant tree species in each compartment. The habitatdata were extracted from the official inventory andmanagement plans and maps (scale 1:10,000) of theforestry authorities. The age of forestry stands was cor-rected according to the date of the forestry map prepa-ration (maximum 9 years before study period), which isactualised every 10 years.

Data analysis

To find the best predictors of bird density, the multipleforward stepwise regression was used (Sokal and Rohlf1995). The variables expressed as proportions (area ofthree main distinguished habitats and area of differentdeciduous age stands) were transformed with the arc-sine (x) function for normalised values. The density ofbirds and area of study plots were log-transformed.Because some of the habitat variables could be redun-dant in contribution to the final model of regression asan effect of the intercorrelation of variables, the toler-ance of variables was defined as 0.6. In this way thereliability of regression coefficients increases. The per-centage of variation explained by each model was basedon an adjusted R2. The fit of the models was based ontesting the residuals normality using the Lillieforsprobabilities.

Results

Density

During the surveys, 390–407 territories of the middlespotted woodpecker were found (see Appendix). On the19 study plots, the average crude density based on anarea surveyed by each observer was 0.66±0.43 territo-ries/10 ha (range 0.1–1.6), while the average ecologicaldensity based on an area of deciduous stands (DS;see Appendix) was 1.09±0.64 territories/10 ha (range0.3–2.2) of potentially available habitats. The highestdensities were recorded in mature, predominantly oak–ash–elm (Fraxino-Ulmetum) riverine forests (plotsKrajkowo and Warta) and mature oak-dominated(Potentillo albae-Quercetum) stands (e.g. plot SwietlistaDabrowa; see Appendix). Correlation between crudedensity and total area across the study plots was nega-tive and statistically significant (r=�0.508, p=0.026,slope of the regression of density on area b=�0.55),while the relationship between ecological density andarea of deciduous forest was insignificant (r=�0.372,p=0.116, b=�0.3).

265

Habitat selection

A correlation analysis indicated that the crude density ofthe middle spotted woodpecker was significantly posi-tively correlated with the percentage of deciduous stands(r=0.605, p=0.006, b=1.72), but it was highly nega-tively related to the percentage of coniferous standsFig.2. However, the proportions of deciduous andconiferous stands were highly negatively correlated(r=�0.859, p < 0.001, b=1.21 if coniferous standswere treated as an independent variable). Stepwisemultiple regression indicated that the percentage ofconiferous stands was the best single factor explainingthe 50% of variation of crude density (Table 1).

It was found that ecological density was significantlynegatively correlated with the percentage of young( £ 40 years old) deciduous stands and positively af-fected by the percentage of the oldest (>120 years old)stands (Fig. 3). Moreover, slightly negative correlationaccording to the share of middle (41–80 years old)deciduous stands (r=�0.447, p=0.055, b=�2.0) wasfound. However, there was significant multicollinearitybetween habitat variables: proportion of middle and theoldest rough-barked deciduous stands (r=�0.774,

p<0.001), as well as between the oldest stands andproportion of smooth-barked stands ( £ 120 years old)(r=�0.507, p=0.027). In the final model of multipleregression the percentage of the young and the oldestforest stands explained 45% of the total variation of birddensity, however, the effect of the oldest stands wasstatistically insignificant (Table 1, Fig. 3). When thelatter variable was removed from the model, the per-centage of young deciduous stands explained 36% of thetotal variation (p=0.004). In the cases of both modelsthe distributions of residuals did not differ from thenormal distribution (Lillefors probabilities—p<0.15and p>0.20 respectively).

Discussion

The ecological breeding densities found in those large-scale studies are close to those in typical lowland foresthabitats in Europe (Pasinelli 2003). Similar to earliersurveys, the highest densities of the species were reportedfrom riverine, partly flooded forests, probably due to theeffect of the high diversity of vegetation, mainly treespecies diversity and vertical diversity of the tree layer(Spitznagel 1990; Pavlık 1994). In consequence, riverineforests were assumed to be its original habitat and themiddle spotted woodpecker is seen as the most typicalwoodpecker in floodplain forests (Spitznagel 1990).

It is well known that estimates of density are not alwaysindependent of the census area (Scherner 1981; Haila1988; Gaston et al. 1999). Scherner (1981) suggests thatrelations between densities and areas of different size arenot meaningful and are statistically invalid. However,other authors have claimed that this is a misconception(Prairie and Bird 1989; Gaston et al. 1999). In spite ofthese different points of view it is a fact that high densitiesgenerally refer to small areas, whereas large-scale plotsyield low values (e.g. Gaston et al. 1999; Pasinelli 2003).Our surveys were performed over study areas of differentsizes. As they become larger the tendency to includehabitats that are not used by birds increases. In this waycruder (lower) densities are generated. On the other hand,the smallest plots were established in rather homogenousdeciduous forest, which generate estimates of ecological

Fig. 2 Correlation between crude density of the middle spottedwoodpecker Dendrocopos medius according to proportion ofconiferous stands (r=�0.73, p=0.0004, b=�2.91)

Table 1 Results of forwardstepwise regression analysiswith two measures of densitiesas dependent and habitatfactors as independentvariables. Given are coefficients(b), their standard errors (SE),tolerance-measure ofintercorrelation betweenindependent variables (range 0–1, with 1=no intercorrelations),t-test and two-tailedprobabilities that b differs fromzero (p)

Variable b SE Tolerance t P

Crude densityConstant 2.537 0.251 10.10 <0.001Coniferous forest �2.905 0.668 1.0 �4.35 <0.001Model: F1,17=18. 918, p< 0.00044, SE=0.593, R2

adj

=0.50, n=19Ecological densityConstant 2.367 0.228 10.38 <0.001Young deciduous stand(0–40 years old)

�1.918 0.806 0.802 �2.38 0.030

The oldest deciduous stand(>120 years old)

0.641 0.340 0.802 1.89 0.078

Model: F2,16=8.241, p < 0.0035, SE=0.472, R2adj=0.45, n=19

266

density. It is worth noting that in the case of the ecologicaldensity–area relationship, correlation was insignificant.Hence, it should be stated that ecological densities werenot confound by the areas over which the densities werecalculated. Among several other possible reasons whichcould inflate the negative correlation between density andarea, i.e. edge effects, scaling of plot size, samplingintensity and variation of habitat type (Gaston et al.1999), the edge effects seem to be the most important.Small and elongated plots have a high edge to area ratioand, as a consequence, some of the territories could liemostly outside them. Our results are unlikely to have beenseriously negatively affected by this factor because thesmallest plots (72 ha) were approximately one order ofmagnitude larger (tenfold) than the average area(7.2±3.0 ha) required by a breeding pair in thepre-breeding season (Pasinelli et al. 2001).Moreover, theywere well separated from adjacent areas by other habitatsor types of forests. The results suggest that the ecologicaldensities obtained from sufficiently large plots (more than

ca 70 ha) could be valuable for density comparisons, e.g.for analysing variation in density and its relation to othervariables.

Our findings confirm an earlier suggestion that themiddle spotted woodpecker avoids coniferous forestsand prefers deciduous stands (e.g. Muller 1982; Pasinelli2003). It is worth noting that the coniferous stands,which covered a relatively small area of the study plots(average 30%), were the single, negative factor explain-ing the variation of crude density. Such a result could bepartly explained as an effect of the presence of habitatsthat are not used by birds. On the other hand, the in-crease of the share of coniferous forest may cause thedecrease of the contribution of the deciduous stands.The latter become smaller, patchily distributed and moreisolated and, therefore, less suitable for the middlespotted woodpecker (Kosenko and Kaygorodova 2001;own unpublished data).

The latter generalisations have ascertained that one ofthe main ecological factors influencing the density of themiddle spotted woodpecker includes the age of the foreststand (del Hoyo et al. 2002; Pasinelli 2003). However, theshare of different age classes of deciduous stands was notdirectly quantified. The results of our study confirm thisstatement because density was positively related to theshare of the oldest (>120 years old) deciduous foreststands (see also Lovaty 1980). However, the finalmodel ofmultiple regression indicates that the density was nega-tively related to the percentage of the young ( £ 40 yearsold) deciduous stands. These forest stands are generallynot accessible for nesting or foraging sites for this species(Lovaty 1980; Buhlmann and Pasinelli 1996). Moreover,the middle spotted woodpeckers have rarely been foundin stands younger than 80 years old (own unpublisheddata). Contrary to our expectations, we did not find anynegative relationship between the smooth-barked decid-uous stands and breeding density. The detailed analysis ofmaps andmanagement plans revealed that pairs occupiedsome beech stands as an effect of an admixture of old oaksor as an effect of bordering smooth- and rough-barkedstands. Such mosaic forests could be suitable habitat forthe middle spotted woodpecker (see review in Pasinelli2003). Furthermore, the lack of any significant effect maybe a consequence of the relatively small share of this foresttype within the sample surveyed.

Our findings indicate that on the level of macrohabitatscale, the negative features of habitat (the share ofunsuitable forest stands) seem to play a major role indetermining the density of the middle spotted wood-pecker. Moreover, these factors explain to a large degreethe amount of variation of breeding density. It should bepointed out that the large-scale study of Muller (1982)explained only 27% of total variation of the middlespotted woodpeckers’ breeding density. He revealed thatthe density was positively related to size and negatively tothe isolation of oak forests. Forests larger than 30 ha andthose that lie close than 9 km were more likely to be col-onised (Muller 1982). It should be stated that other factorsoperating on a smaller spatial scale, e.g. proportion or

Fig. 3 Correlation between ecological density of the middle spottedwoodpecker according to a proportion of young deciduous stands(r=�0.63, p=0.0038, b=�2.60) and b the oldest deciduous stands(r=0.58, p=0.0097, b=1.00)

267

density of old oaks (Muller 1982; Schmitz 1993) and oakvolume (Buchlmann and Pasinelli 1996), as well as theavailability of potential cavity trees (Pasinelli 2000), couldexplain the undetected part of the density variation.

The results of our and other studies (Muller 1982;Pasinelli 2000; Kosenko and Kaygorodova 2001; Buhl-mann et al. 2003) imply that forest management shouldfocus on the continuity of the most suitable forest stands(older than 120 years) appropriate for nesting and for-aging to support the middle spotted woodpecker long-term. Moreover, the restriction or abandonment of largescale clear-cutting of oak forests and promotion ofnatural processes in modern forestry characterised bysmall-gap dynamics (Angelstam et al. 2004) could pro-vide for a continuous supply of habitats suitable for themiddle spotted woodpecker.

Zusammenfassung

Faktoren fur die Beeinflussung der Populationsdichtedes Mittelspechts (Dendrocopos medius): ein Makro-habitat-Ansatz

Das Hauptziel dieser Studie war es, die Zusammenhangezu untersuchen zwischen der Dichte der Brutpopulatio-nen desMittelspechts auf 19 Großflachen und demAnteilverschiedener Habitate und Alter von Baumbestanden.Eine durchschnittliche grob geschatzte Dichte auf einervon den Beobachtern frei gewahlten Flache betrug0.66±0.43 Territorien pro Hektar, wahrend die okolo-gische Dichte, ermittelt auf Flachen mit Habitaten, diepotentiell vonMittelspechten genutzt werden, einenWertvon 1.09±0.64 Territorien pro Hektar erreichte.

Eine schrittweise Multiple Regression zeigte, dass diegeschatzte Dichte negativ korreliert war mit dem Anteilvon Nadelwald, wodurch 50% der Streuung erklartwurden. Die okologische Dichte war negativ korreliertmit dem Anteil junger Laubbaumbestande (0–40 Jahre).Diese Variable erklarte 36% der gesamten Streuung.Diese Ergebnisse deuten darauf hin, dass im Maßstabvon Makrohabitat-Analysen der Anteil von fur die Artungeeigneten Baumbestanden eine bedeutende Rollespielt in der Ermittlung der Dichte des Mittelspechts.

Acknowledgements We are most grateful to Jan Bednorz, KarolDrab, Marek Ilkow, Marcin Kempa, Paweł Ksit, Roman Kubacki,Maciej Lesniczak, Sylwester Lisek, Krystyna Sliwa, Paweł Sliwa,Dawid Tatarkiewicz, Przemysław Wylegała, Sylwia Wylegała andJacek Wyrwał for their assistance in collection of data. We wish toexpress our thanks to the Regional Directorate of the State Forestsin Poznan and Piła for forest maps made available to us. We thankPiotr Tryjanowski and two anonymous reviewers for their helpfulcomments and Robert Kippen who improved the English.

Appendix

Data for the analysed study plots No.Name

Area(ha)Dominatingdeciduousforest

standsTypeofhabitat(ha)

Ageclasses

ofstands(ha)

YearNo.ofterritories

No.ofcensuses

Rough-barked

Smooth-

barked

DS

CS

OA

UA

0–40

41–80

81–120

>120

<121

‡121

1ZielonaGora

219.1

Oak–hornbeam

211.3

3.1

4.5

0.1

17.5

25.1

64.7

100.7

3.3

0.0

2001

21–23

22

Czarnkow

72.5

Oak-hornbeam

58.6

11.0

2.1

0.9

5.0

11.8

27.1

6.1

8.6

0.0

2001

62

3Swietlista

Dabrowa

79.9

Oak

59.7

15.0

0.0

5.1

7.8

0.0

0.0

51.9

0.0

0.0

2001

13

14

Gora

193.0

Oak–beech

97.7

87.1

8.2

0.0

10.3

25.5

34.1

10.1

10.7

7.0

2002

18

35

Ławica

143.0

Beech

andalder

96.2

36.1

10.9

0.0

1.5

40.8

23.8

0.0

19.0

11.1

2002

53

6Łoskon

876.2

Oakandbeech

568.2

233.0

72.7

2.3

101.6

108.0

94.2

29.6

108.3

126.6

2001

41–43

37

Nieszawa

257.4

Oak

121.2

100.2

33.1

2.9

24.1

43.6

50.1

3.4

0.0

0.0

2002

15

38

Pławno

304.5

Oak–hornbeam

139.1

154.3

11.1

0.0

0.0

0.5

0.4

9.6

0.0

0.0

2001

26–27

19

Promno

107.8

Oak–hornbeam

81.7

14.4

4.8

0.0

12.4

23.5

14.9

17.5

14.4

0.0

2003

82

10

Łegi-WPN

349.5

Oak-ash-elm

andwillow–poplar

riverineforest

61.4

222.6

65.5

0.0

28.3

16.8

3.8

0.0

12.5

0.0

2000

43

11

Krajkowo

154.9

Oak–hornbeam

62.1

31.0

61.1

0.7

0.0

4.4

34.8

22.9

0.0

0.0

2000

14

212

Miłosław-I

511.1

Alder

andoak

161.7

334.3

15.2

10.0

75.5

48.5

18.4

9.1

10.3

0.0

2002

62

13

Miłosław-II

601.1

Oak,ash

andalder

341.8

238.5

20.8

7.8

103.7

95.7

86.0

20.3

36.1

0.0

2002

11–12

214

Miłosław-III

889.1

Oakandalder

349.7

418.1

121.3

3.6

155.5

105.4

63.9

6.8

18.1

0.0

2002

10–11

215

Warta

498.4

Oak–ash–elm

riverineforest,

oak–hornbeam

373.4

30.5

78.9

15.5

58.7

76.7

87.0

135.5

15.5

0.0

2000

74–81

4

16

Franciszkow

274.0

Oak–ash–elm

riverineforest

150.9

52.1

56.1

14.9

28.8

77.4

43.1

1.6

0.0

0.0

2000

16–18

2

268

References

Angelstam P, Roberge J-M, Lohmus A, Bergmanis M, Brazaitis G,Donz-Breuss M, Edenius L, Kosinski Z, Kurlavicius P,L�armanis V, L�ukins M, Mikusinski G, Racinskis E, Strazds M,Tryjanowski P (2004) Habitat modelling as a tool for land-scape-scale conservation—a review of parameters for focalforest birds. In: Angelstam P, Donz-Breuss M, Roberge J-M(eds) Targets and tools for the maintenance of forest biodi-versity. Ecol Bull 51: 427�453

Becker M, Heyne K-H (1994) Verbreitung und Bestandsgroße desMittelspechts (Dendrocopos medius) im Raum Trier, westlichesRheinland-Pfalz. Dendrocopos 21:17–33

Bibby CJ, Burgess ND, Hill DA, Mustoe SH (2000) Bird censustechniques. Academic, London

Buhlmann J, Pasinelli G (1996) Beeinflussen kleinflachige Wald-nutzung und Wetter die Siedlungsdichte des MittelspechtsDendrocopos medius. Orn Beob 93:267–276

Buhlmann J, Muller W, Pasinelli G, Weggler M (2003) Entwick-lung von Bestand und Verbreitung des Mittelspechts Dendroc-opos medius 1978–2002 im Kanton Zurich: Analyse derVeranderungen und Folgerungen fur den Artenschutz. OrnBeob 100:343–355

Conrads K, Conrads W (1992) Der Mittelspecht (Picoides medius)im Beller Holz (Kreis Lippe). Ber Naturwiss Ver Bielefeld 33:5–46

del Hoyo J, Elliott A, Sargatal J (eds) (2002) Handbook of thebirds of the world, vol 7. Jacamars to Woodpeckers. Lynx,Barcelona

Fernandez C, Azkona P (1996) Influence of forest structure on thedensity and distribution of the white-backed woodpeckerDendrocopos leucotos and black woodpecker Dryocopus martiusin Quinto Real (Spanish Western Pyrennes. Bird Study 43:305–313

Gaston KJ, Blackburn TM, Gregory RD (1999) Does variation incensus area confound density comparisons? J Appl Ecol36:191–204

Gutzwiller KJ, Anderson SH (1987) Multiscale associations be-tween cavity-nesting birds and features of Wyoming streamsidewoodlands. Condor 89:534–548

Gunther E (1992) Untersuchung zum Brutbestand, zur Bestand-sentwicklung und zum Habitat des Mittelspechtes (Dendrocoposmedius) im nordostlichen Harz (Sachsen-Anhalt). Orn Jber MusHeineanum 10:31–53

Gunther E, Hellmann M (1997) Der Mittelspecht und die Buche:Versuch einer Interpretation seines Vorkommens in Buchen-waldern. Orn Jber Mus Heineanum 15:97–108

Haila Y (1988) Calculating and miscalculating density: the role ofhabitat geometry. Ornis Scand 19:88–92

Hilden O (1965) Habitat selection in birds: a review. Ann ZoolFenn 2:53–75

Johnson RR, Brown BT, Haight LT, Simpson JM (1981) Playbackrecordings as a special avian censusing technique. In: Ralph CJ,Scott JM (eds) Estimating numbers of terrestrial birds. StudAvian Biol 6:68–75

Kosenko SM, Kaygorodova EY (2001) Vliyanie fragmentatsiimestoobitaniya na raspredelenie, plotnost‘‘ naseleniya i prod-uktivnost‘‘ razmnozheniya srednego dyatla Dendrocopos medius(Aves, Picidae) v Nerusso-Desnyanskom Poles‘‘e [Effect ofhabitat fragmentation on distribution, density and breedingperformance of the middle spotted woodpecker Dendrocoposmedius (Aves, Picidae) in Nerussa-Desna Polesye]. Zool Zh80:71–78

Kosinski Z, Winiecki A (2003) Ocena liczebnosci dzieciołasredniego Dendrocopos medius—porownanie metodykartograficznej z uzyciem stymulacji magnetofonowej zmetoda wyszukiwania gniazd [Estimation of the middlespotted woodpecker Dendrocopos medius numbers—acomparison between the mapping technique combined withaudio stimulation and nest searching method]. Not Orn44:43–551

7Bieniszew

484.4

Oak–hornbeam

269.1

174.3

36.5

4.5

15.3

39.0

205.1

0.0

9.7

0.0

2001

16

118

Stare

Budy

643.5

Oak

614.7

13.3

15.6

0.0

44.9

46.6

92.8

430.4

0.0

0.0

2001

57–58

319

Smoszew

587.7

Oak

312.5

256.1

14.5

4.6

38.0

42.1

82.3

118.1

32.0

0.0

2001

29

3Mean

381.4

217.5

127.6

33.3

3.8

38.4

43.8

54.5

15.7

15.7

7.6

Me

304.5

150.9

87.1

15.6

2.3

24.1

40.8

43.1

10.3

10.3

0.0

SD

254.7

169.7

125.1

33.5

4.9

42.8

34.2

48.2

24.8

24.8

29.0

DS,deciduousstand;CS,coniferousstand;OA,open

areas;UA,unidentified

areas.

269

Kosinski Z, Kempa M, Hybsz R (2004) The accuracy and efficiencyof different techniques for censusing territorial middle spottedwoodpeckers Dendrocopos medius. Acta Ornithol 39:29–34

Lambeck RJ (1997) Focal species define landscape requirements fornature conservation. Conserv Biol 11:849–856

Lovaty F (1980) L’abondance des oiseaux nicheurs a grands can-tons dans les chenaies equiennes de la region de Moulins (Al-lier). Alauda 48:193–207

Mikusinski G, Angelstam P (1997) European woodpeckers andanthropogenic habitat change: a review. Vogelwelt 118:277–283

Miranda B, Pasinelli G (2001) Habitatanspruche des Kleinspechts(Dendrocopos minor) in Waldern der Nordost-Schweiz. J Orni-thol 142:295–305

Muller W (1982) Die Besiedlung der Eichenwalder im KantonZurich durch den Mittelspecht Dendrocopos medius. Orn Beob79:105–119

Noah T (2000) Siedlungsdichte, Habitat und Bestandsentwicklungder Spechte im NSG ‘‘Innerer Unterspreewald‘‘. Otis 8:75–98

Pasinelli G (2000) Oaks Quercus sp. and only oaks? Relations be-tween habitat structure and home range size of the middlespotted woodpecker Dendrocopos medius. Biol Conserv 93:227–235

Pasinelli G, Hegelbach J, Reyer H-U (2001) Spacing behavior ofthe middle spotted woodpecker in Central Europe. J WildManage 65:432–441

Pasinelli G (2003) Dendrocopos medius middle spotted woodpecker.BWP Update 5:49–99

Pavlık S (1994) A model of the influence of some environmentalfactors on the population density of the great spotted wood-pecker (Dendrocopos major) and the middle spotted wood-pecker (D. medius). Biologia (Bratislava) 49:767–771

Pettersson B (1985) Extinction of an isolated population of themiddle spotted woodpecker Dendrocopos medius (L.) in Swedenand its relation to general theories on extinction. Biol Conserv32:335–353

Prairie YT, Bird DF (1989) Some misconceptions about spuriouscorrelation problem in the ecological literature. Oecologia82:285–288

Randler Ch (2000) Verbreitung, Bestand und Siedlungsdichte desMittelspechts Dendrocopos medius im Stromberg, Nordwurt-tenberg. Orn Anz 39:197–206

Robles H, Olea PP (2003) Distribution and abundance of middlespotted woodpecker Dendrocopos medius in a southern popu-lation of the Cantabrian Mountains. Ardeola 50:275–280

Rolstad J, Løken B, Rolstad E (2000) Habitat selection as a hier-archical spatial process: the green woodpecker at the northernedge of its distribution range. Oecologia 124:116–129

Scherner ER (1981) Die Flachengroße als Fehlerquelle bei Brut-vogel-Bestandsaufnahmen. Okol Vogel (Ecol Birds) 3:145–175

Schmitz L (1993) Distribution et habitat du Pic mar (Dendrocoposmedius) en Belgique. Aves 30:145–166

Spitznagel A (1990) The influence of forest management onwoodpecker density and habitat use in floodplain forests of theUpper Rhine Valley. In: Carlson A, Aulen G (eds) Conserva-tion and management of woodpecker populations. SwedishUniversity of Agricultural Sciences, Department of WildlifeEcology, Report 17. Uppsala, Sweden

Sokal RR, Rohlf FJ (1995) Biometry. The principles and practicein statistics in biological research. Freeman, New York

Sudbeck P, Gall T (1993) Der Mittelspecht (Picoides medius) inSchleswig-Holstein—Erfassungsprobleme und ihre Konse-quenzen fur Bestandsschatzungen. Corax 15:211–221

Tomiałojc L (1980) The combined version of the mapping method.In: Oelke H (ed) Proceedings of the Sixth International Con-ference on bird census work and nature conservation, Gottin-gen, pp 92–106

Wesołowski T (1995) Value of Białowie _za forest for the conserva-tion of white-backed woodpecker Dendrocopos leucotos in Po-land. Biol Conserv 71:69–75

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