Occurrence of breeding bird species in urban parks - Springer Link

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Abstract. Occurrences of breeding bird species in 54 urban parks were investigated in the city of Oulu in northern Finland. Park area, human activity, habitat, and ...
Urban Ecosystems, 3, 21–34, 1999 c 2000 Kluwer Academic Publishers. Manufactured in The Netherlands. °

Occurrence of breeding bird species in urban parks: Effects of park structure and broad-scale variables ¨ JUKKA JOKIMAKI Arctic Centre, University of Lapland, P.O. Box 122, FIN-96101 Rovaniemi, Finland

[email protected]

Abstract. Occurrences of breeding bird species in 54 urban parks were investigated in the city of Oulu in northern Finland. Park area, human activity, habitat, and landscape structure within a 9-ha square surrounding the study park were related to the bird species richness and occurrence of individual bird species. A total of 22 species was observed. The area of the park explained 39% of the variance of species richness. Seven species (wheatear [Oenanthe oenanthe], common rosefinch [Carpodacus erythrinus], garden warbler [Sylvia borin], lesser whitethroat [Sylvia curruca], linnet [Acanthis cannabina], redpoll [Carduelis flammea], and yellowhammer [Emberiza citrinella]) were not detected in parks of 5–10 m, >10–15 m, and >15 m) within each sampling point. Values for shrubs and trees were converted to densities (average number of shrubs or trees/ha). The tree species and foliage height diversity (Shannon formula (Begon et al., 1990)) were calculated from the tree species frequency series. The height of the dominant trees (m) in each park was measured using a hypsometer. I also counted the number of nest boxes in each park. Because of their small sizes (28 m2 ), vegetation plots were not intended to describe park vegetation structure in detail. However, since each study park included only managed or unmanaged habitats, each was homogeneous in respect to its management status and general habitat structure. Therefore it is supposed that the sampling design used gives an adequate estimate of the general structure of the study parks.

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Table 1. Proportion of the breeding occurrence (%) of different bird species in different park size classes and in the whole study area, and the total number of pairs. ≤0.5 ha (N = 23)

≥0.75–1 ha (N = 19)

≥1.5–7 ha (N = 12)

Total occurence (%)

Total number of pairs

Chaffinch Fringilla coelebs (TD)

30

63

50

46

29

Great tit Parus major (CD)

30

53

59

44

24

Willow warbler Phylloscopus trochilus (GD)

13

42

59

41

31

Fieldfare Turdus pilaris (TD)

26

32

50

33

38

9

37

50

28

15

Blue tit Parus caeruleus (CD)

19

21

67

26

14

Greenfinch Carduelis chloris (TD)

19

42

33

26

14

Pied flycatcher Ficedula hypoleuca (CD)

13

21

42

22

14

Pied wagtail Motacilla alba (GO)

17

21

25

20

11

Magpie Pica pica (T-)

22

5

33

19

10

Spotted flycatcher Muscicapa striata (CC)

9

21

25

17

8

Redstart Phoenicurus phoenicurus (CD)

4

16

25

13

7

Bird species

Hooded crow Corvus corone cornix (T-)

Rook Corvus frugilegus (T-)

9

5

17

9

32

Siskin Carduelis spinus (SC)

4

5

17

7

4

Redwing Turdus iliacus (SD)

9

0

8

6

3

Wheatear Oenanthe oenanthe (GO)

0

0

25

6

3

Rosenfinch Carpodacus erythrinus (SD)

0

5

8

4

2

Garden warbler Sylvia borin (SD)

0

5

0

2

1

Lesser whitethroat Sylvia curruca (SD)

0

5

0

2

1

Linnet Acanthis cannabina (SD)

0

0

8

2

1

Redpoll Carduelis flammea (SD)

0

0

8

2

1

Yellowhammer Emberiza citrinella (GO)

0

0

8

2

1

The letters after the bird species indicate the breeding habits of the species according to von Haartman et al. (1963–72) (T = nesting mainly in trees, C = in cavities, G = on ground, and S = in shrubs) and the main habitat type (D = deciduous forest species, C = coniferous forest species, O = open area species).

Six broad-scale landscape variables were measured from the city map (Table 2). I estimated the proportion of the different habitat types (parks, built-up areas, open areas) within a 9-ha square around the study parks and calculated the diversity of the surrounding landscape by the Shannon formula. Three different variables were measured to describe the level of isolation. These measurements described the distances from the study parks to the nearest woods or parks and the proportion of the park area adjacent to the study parks (Table 2). Data analyses Variables with nonnormal distributions were either log or arcsin transformed. Analyses were carried out on breeding bird species richness and the occurrence of individual bird species.

BIRDS IN URBAN PARKS: A LANDSCAPE ECOLOGICAL VIEW Table 2.

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Variables used in logistic regression analysis.

Variables within the park boundary Recreational activity (Mean number of people/park/visit) (RECREATION) Area of park (ha) (AREA) Density of shrubs (/ha) log-transformed (SHRUBS) % of trees >2–5 m of the total density of trees (TREE 1) % of trees >5–10 m of the total density of trees (TREE 2) % of trees >10–15 m of the total density of trees (TREE 3) % of trees >15 m of the total density of trees (TREE4) % of deciduous trees of the total density of trees (DECITREE) Total density of trees (/ha) (TREEDEN) Height of the dominant trees (m) (TREEHEI) Tree species diversity (Shannon index) (TREEDIV) Foliage height diversity of the tree cover (Shannon index) (FHD) Total number of nest boxes (NBOXES) Broad-scale variables Total length of streets within a 9-ha square surrounding the study park (STREETS) % of block of flats area within a 9-ha square surrounding the study park (FLATS) Isolation I (Distance to the nearest wood or park of >2.2 ha, m, log-transformed) (ISO1) Isolation II (Distance to the nearest wood or park >9 ha, m) (ISO2) Isolation III (Proportion of park area within a 9-ha square surrounding the studied park) (ISO3) Diversity of the surrounding landscape within a 9-ha square surrounding the park (LDIV)

The variation in species richness was analysed by forward-stepwise multiple regression analysis, and all breeding species were included in the analysis. The existence of individual bird species (presence/absence) was modeled using a forward-stepwise logistic regression analysis (see Trexler and Travis, 1993), since most of the bird species were absent, or only one pair of the species bred in the study park. Species occurring in fewer than 10% of the parks were omitted from that analysis because of the small sample size (see Table 1). The dependent variable, presence or absence of each species in each park, was scored as 1 or 0, respectively. The significance of each variable included in the models is based on the Wald test (Hosmer and Lemeshow, 1989). The best models were not selected on purely statistical grounds. I included only ecologically meaningful variables in the models. Therefore some variables with an individual significance slightly less than the conventionally accepted p = 0.05 level were included in some models (Table 3).

Results A total of 22 bird species bred in the study parks (N = 54) of Oulu (Table 1). The average number of breeding bird species per study park was lower in small-sized parks (x¯ = 2.1, SD = 2.6) than in large-sized (x¯ = 5.9, SD = 3.7) or medium-sized parks

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Table 3. Logistic regression models for the individual bird species. The abbreviation of each variable is given in Table 1. Negative coefficients are indicated with -. The significance of each coefficient is based on Wald test (∗∗ P < 0.01, ∗ P < 0.05 and ◦ P < 0.10). The “adequacy” of each model is assessed with the fit of its predictions to data (goodness-of-fit, G 2 ). Common names of bird species are given in Table 1. Species

Variables

G2

P

Fringilla coelebs

No model

Phylloscopus trochilus

FLATS(-)∗

6.1

0.0132

Corvus corene cornix

FLATS(-)∗

6.2

0.0132

Ficedula hypoleuca

NBOXES∗∗ ,

Turdus pilaris

TREEHEI∗ , ISO3∗

13.9

Parus caeruleus

AREA∗∗

15.0

Carduelis chloris

SHRUBS(-)∗ , AREA◦ ,TREE4(-)◦

18.3

Motacilla alba

TREEDEN(-)∗

Parus major

TREE2∗∗ , LDIV(-)∗

16.4