Anvils of the Great Spotted Woodpecker (Dendrocopos major) in primeval oak-lime-hornbeam stands of the Białowieża National Park

Figures & data

Table I. Tree species selected for the anvils by males, females and all woodpeckers

	Resource	Anvils used by males		Anvils used by females		All anvils
	%	%	Selection index	%	Selection index	%	Selection index
Tree species
Oak	2.73	26.89	9.84 (5.72–13.96)	33.55	12.28 (8.43–16.12)	30.45	11.14 (8.68–13.61)
Hornbeam	33.18	22.69	0.68 (0.36–1.00)	21.29	0.64 (0.37–0.92)	21.51	0.65 (0.47–0.83)
Maple	4.00	16.81	4.20 (1.83–6.58)	16.13	4.02 (1.99–6.08)	15.92	3.98 (2.64–5.32)
Lime	38.03	13.45	0.35 (0.13–0.58)	10.97	0.29 (0.11–0.47)	12.85	0.42 (0.28–0.56)
Spruce	14.92	12.61	0.85 (0.28–1.41)	7.74	0.52 (0.12–0.92)	9.78	0.66 (0.36–0.95)
Pine	0.57	4.20	7.36 (0.00–16.28)	2.58	4.52 (0.00–10.70)	3.63	6.36 (1.56–11.15)
Ash	1.22	0.84	0.68 (0.00–2.58)	0.65	0.53 (0.00–1.98)	1.12	0.91 (0.00–2.17)
Aspen	0.73	2.52	3.43 (0.00–8.86)	6.45	8.79 (1.24–16.23)	4.47	6.08 (1.97–10.21)
Elm	3.49	-	-	0.65	0.18 (0.00–0.69)	0.28	0.08 (0.00–0.30)
Other	1.13	-	-	-	-	-	-
Tree condition
Alive	93.47	78.15	0.84 (0.72–0.95)	76.13	0.81 (0.71–0.92)	77.13	0.82 (0.76–0.89)
Dead	6.53	21.85	3.35 (1.74–4.96)	23.87	3.66 (2.20–5.11)	22.87	3.51 (2.57–4.45)

Selection indices with 95% confidence limits (in brackets) are shown. Results statistically significant are in bold.

Figure 1. Percentage distribution of anvils on alive (dark colour) and dead (pale colour) trees from particular species. Numbers in brackets indicate sample size

Figure 2. Median diameter at breast height (DBH) of trees with anvils compared to available trees in resources from particular species. Whiskers indicate 25–75% quartile ranges

Table II. Number (N) and percentage distribution (%) of anvils in relations to: type of substrate, its condition, diameter and height

	Anvils used by males		Anvils used by females		All anvils
Parameters of anvils	N	%	N	%	N	%
Type of substrate
Trunk	35	29.41	47	30.32	99	27.65
Branch	84	70.59	108	69.68	259	72.35
Condition of substrate
Alive	44	36.97	52	33.55	119	33.24
Dead	75	63.03	103	66.45	239	66.76
Diameter of substrate
< 5 cm	9	7.56	9	5.81	29	8.10
5–10 cm	49	41.18	69	44.52	160	44.69
10–20 cm	36	30.25	38	24.52	95	26.54
>20 cm	25	21.01	39	25.16	74	20.67
Height
< 5 m	6	5.04	7	4.52	15	4.19
5–10 m	5	4.20	9	5.81	15	4.19
10–15 m	15	12.61	17	10.97	51	14.25
15–20 m	40	33.61	57	36.77	129	36.03
>20 m	53	44.54	65	41.94	148	41.34

Table III. The diameter at breast height (DBH) of trees with anvils and height of anvil location in relation tree species

Tree species	Anvils used by males				Anvils used by females
DBH (cm)	N	Me	Min	Max	N	Me	Min.	Max.
Oak	32	100.0 (80.0–120.0)	61	134	52	99.0 (85.5–123.5)	60	166
Hornbeam	27	45.0 (41.0–50.0)	33	68	33	48.0 (38.0–54.0)	30	73
Maple	20	70.1 (61.6–84.1)	40	108	25	69.0 (57.0–81.0)	42	108
Lime	16	95.5 (77.0–103.5)	13	119	17	90.0 (76.0–111.0)	40	135
Spruce	15	57.0 (36.0–63.0)	18	106	12	38.5 (33.5–49.0)	25	60
Pine	5	65.0 (60.0–82.0)	30	96	4	55.5 (44.0–75.5)	44	84
Ash	1	75.0			1	69.0
Aspen	3	61.0 (54.0–83.0)	54	83	10	58.5 (54.0–72.0)	48	76
Elm					1	21.0
Height (m)
Oak	32	20.5 (17.5–25.0)	4.0	32.0	52	21.5 (17.0–25.0)	1.0	34.0
Hornbeam	27	16.0 (13.0–18.0)	7.0	27.0	33	16.0 (14.0–17.0)	0.7	25.0
Maple	20	20.5 (18.0–25.0)	1.0	30.0	25	20.0 (18.0–23.0)	16.0	25.0
Lime	16	20.5 (17.0–22.0)	0.3	30.0	17	22.0 (16.5–25.0)	8.0	28.0
Spruce	15	25.0 (21.0–32.0)	1.6	41.0	12	22.0 (19.5–25.5)	17.0	38.0
Pine	5	22.0 (21.0–24.0)	16.0	27.0	4	25.5 (24.5–26.5)	24.0	27.0
Ash	1	20.0			1	17.0
Aspen	3	19.0 (18.0–27.0)	18.0	27.0	10	16.5 (14.0–18.0)	3.0	23.0
Elm					1	10.0

Abbreviations: N – number of trees with anvils, Me – median with 25–75% quartile ranges (in brackets), Min – minimum and Max – maximum values.

Table IV. Results of generalised linear model assessing the differences between males and females of the Great Spotted Woodpecker in the selection of anvil placement sites

Parameters of anvils	df	Wald χ^2	p
Intercept	1	0.00	0.997
DBH	1	0.06	0.811
Height	1	0.04	0.840
Tree species	8	5.58	0.695
Tree condition	1	0.51	0.476
Tree substrate	1	0.08	0.775
Condition of substrate	1	0.32	0.573
Diameter of substrate	3	1.40	0.706