Assessing breeding success in common woodland birds using a novel method

Figures & data

Table 1. Characteristics of the larger woodland blocks in which the study sites were situated. All six study sites were composed primarily of lowland mixed broadleaf woodland, NVC W8 or W10 (Rodwell 1991), the commonest type of lowland woodland in this region of England (Forestry Commission 2003) with other patches of woodland type as indicated. All six study sites were of a similar size (15 ha ± 0.5 ha) and comprised part of the larger blocks as indicated.

Region	Location 10-km national grid square	Total woodland area (ha)	Other woodland types within each of the lowland mixed broadleaf blocks
Hampshire	SU30	35	Some conifer mix
Hampshire	SU40	28	Some conifer mix
Norfolk/Suffolk	TM39	20	All deciduous, younger oak patch
Norfolk/Suffolk	TM48	33	Mostly deciduous, younger oak patch
Leicestershire	SK70	36	Conifer patch, rides
Leicestershire	SK70	29	Conifer patch

Table 2. For 19 bird species recorded from all six study sites, the mean number, by wood, of breeding territories and fledged broods (first broods only), mean number of times each brood was seen, mean duration of encounters with these fledged broods (excluding broods encountered only once) ± 1 se in all cases. Fledging to maturity (Fl – Mat) is taken from Cramp (1985, 1988, 1992) and Cramp & Perrins (1993, 1994). The table is ordered by the naive Territory Occupancy Probability (by fledged broods, TOP). Estimated TOPs take into account detectability of fledged broods using detection probabilities (see Methods and Table 3). The naive and estimated TOPs for fledged broods of a species tend to be more different when the Daily Detection Probabilities (DDP) of fledged broods in Table 3 are low and vice versa. [GS Woodpecker = Great Spotted Woodpecker.]

Species	Breeding pairs	Fledged broods	Times seen	Duration (days)	Fl – Mat (days)	Naive TOP	Est. TOP
Nuthatch	3.67 ± 0.62	3.67 ± 0.62	5.11 ± 1.22	21.22 ± 2.28	15	1.000	1.00 ± 0.00
Marsh Tit	4.83 ± 1.22	4.50 ± 1.15	4.28 ± 0.92	18.30 ± 1.65	19	0.931	0.95 ± 0.05
Coal Tit	4.83 ± 0.75	4.33 ± 0.88	2.80 ± 0.64	24.18 ± 6.18	19	0.896	1.00 ± 0.00
Long-tailed Tit	6.17 ± 1.85	5.17 ± 1.49	5.99 ± 1.32	33.37 ± 9.58	16	0.838	0.84 ± 0.06
Great Tit	12.2 ± 1.45	9.83 ± 2.21	2.90 ± 0.48	19.42 ± 4.02	19	0.829	0.91 ± 0.05
Blue Tit	16.8 ± 2.28	13.7 ± 1.59	2.74 ± 0.41	13.67 ± 3.80	19	0.820	0.86 ± 0.04
GS Woodpecker	2.83 ± 0.40	2.17 ± 0.48	1.80 ± 0.58	10.00 ± 6.44	12	0.765	1.00 ± 0.00
Treecreeper	3.50 ± 0.85	3.67 ± 0.99	3.35 ± 1.29	14.27 ± 6.07	16	0.762	0.77 ± 0.09
Song Thrush	3.33 ± 0.62	2.50 ± 0.34	2.81 ± 0.90	17.60 ± 8.61	14	0.750	0.83 ± 0.11
Dunnock	3.67 ± 0.84	2.17 ± 0.65	1.60 ± 0.20	16.00 ± 3.41	12	0.619	0.92 ± 0.23
Wren	16.0 ± 1.27	9.67 ± 1.86	2.55 ± 0.44	16.48 ± 2.63	17	0.606	0.65 ± 0.06
Goldcrest	4.50 ± 0.96	2.83 ± 1.05	3.67 ± 1.30	13.65 ± 6.06	19	0.593	0.61 ± 0.10
Chaffinch	11.5 ± 1.88	6.67 ± 1.20	2.01 ± 0.29	12.02 ± 5.56	14	0.582	0.71 ± 0.08
Robin	18.8 ± 0.79	11.2 ± 1.49	2.73 ± 0.31	18.57 ± 5.41	14	0.581	0.65 ± 0.05
Blackbird	9.17 ± 0.40	5.00 ± 1.03	2.14 ± 0.51	18.83 ± 7.42	14	0.566	0.66 ± 0.09
Chiffchaff	8.67 ± 1.91	4.50 ± 1.38	1.86 ± 0.29	7.63 ± 2.06	15	0.539	0.72 ± 0.11
Blackcap	9.50 ± 1.43	4.83 ± 1.05	1.64 ± 0.22	10.14 ± 2.06	11	0.509	0.63 ± 0.09
Bullfinch	1.83 ± 0.47	0.67 ± 0.21	3.50 ± 1.04	11.67 ± 1.45	15	0.444	0.46 ± 0.17
Garden Warbler	3.00 ± 0.86	1.33 ± 0.42	1.25 ± 0.14	9.33 ± 5.33	10	0.353	0.67 ± 0.37

Table 3 . Fledged brood Daily Detection Probabilities (DDP) for 19 bird species present in all six study woods (two woods per region). These are the probabilities of detecting a brood in any one survey during the fledging to maturity phase for the particular species (see Methods and Table 2). Differences in probabilities between woods were tested and, when significant, differences within pairs were also tested. Mean DDP ± 1 se using wood-means are also given for each species even if differences between woods were found. This is used in combination with the fledging to maturity period for each species to calculate a mean brood Overall Detection Probability (ODP), the probability of detection at least once when visiting woods four times and two times a week. The table is ordered by ODP. [GS Woodpecker = Great Spotted Woodpecker].

Species	Mean DDP + 1 se per survey in each wood – grouped in columns by regional pair			Between woods χ^2 df = 5	Within pairs χ^2 df = 3	Mean DDP per survey	2-visit/week ODP	4-visit /week ODP
	Leicestersh	Suffolk	Hampshire
Long-tailed Tit Aegithalos caudatus	0.82 ± 0.12	0.36 ± 0.08	0.22 ± 0.04	66.3***	4.10 ns	0.51 ± 0.06	0.96	1.00
	0.91 ± 0.06	0.56 ± 0.06	0.23 ± 0.05
Marsh Tit Poecile palustris	0.70 ± 0.08	0.45 ± 0.09	0.13 ± 0.04	14.6**	2.55 ns	0.40 ± 0.08	0.94	1.00
	0.64 ± 0.10	0.30 ± 0.08	0.17 ± 0.04
Bullfinch Pyrrhula pyrrhula	0.44 ± 0.17	0.06 ± 0.06	0.33 ± 0.16	4.58 ns		0.38 ± 0.39	0.87	0.98
	0.44 ± 0.17	0.34 ± 0.15	0.39 ± 0.24
Eurasian Treecreeper Certhia familiaris	0.19 ± 0.15	0.54 ± 0.07	0.11 ± 0.11	31.9***	1.7 ns	0.34 ± 0.04	0.85	0.98
	0.42 ± 0.08	0.67 ± 0.07	0.11 ± 0.06
Goldcrest Regulus regulus	0.21 ± 0.10	0.14 ± 0.07	0.15 ± 0.13	54.1***	30.3**	0.29 ± 0.14	0.84	0.98
	0.96 ± 0.04	0.24 ± 0.05	0.03 ± 0.03
Wood Nuthatch Sitta europaea	0.43 ± 0.09	0.43 ± 0.07	0.11 ± 0.04	48.4***	1.67 ns	0.32 ± 0.06	0.81	0.96
	0.50 ± 0.00	0.30 ± 0.06	0.17 ± 0.04
Coal Tit Periparus ater	0.09 ± 0.05	0.30 ± 0.07	0.12 ± 0.04	17.1**	10.9*	0.22 ± 0.06	0.74	0.93
	0.55 ± 0.15	0.18 ± 0.05	0.12 ± 0.04
Blue Tit Cyanistes caeruleus	0.10 ± 0.04	0.20 ± 0.03	0.29 ± 0.04	28.5***	10.0*	0.22 ± 0.03	0.74	0.93
	0.14 ± 0.04	0.35 ± 0.05	0.26 ± 0.03
Song Thrush Turdus philomelos	0.21 ± 0.10	0.62 ± 0.12	0.13 ± 0.08	13.1 ns		0.27 ± 0.08	0.72	0.92
	0.12 ± 0.11	0.21 ± 0.08	0.31 ± 0.12
Wren Troglodytes troglodytes	0.20 ± 0.05	0.33 ± 0.06	0.08 ± 0.05	20.4**	4.5 ns	0.21 ± 0.04	0.68	0.90
	0.31 ± 0.04	0.24 ± 0.04	0.10 ± 0.04
Robin Erithacus rubecula	0.23 ± 0.06	0.39 ± 0.05	0.23 ± 0.06	18.9*	10.8*	0.24 ± 0.03	0.67	0.89
	0.24 ± 0.05	0.19 ± 0.04	0.15 ± 0.03
Chiffchaff Phylloscopus collybita	0.50 ± 0.00	0.11 ± 0.16	0.32 ± 0.41	10.8 ns		0.23 ± 0.04	0.65	0.89
	0.22 ± 0.80	0.16 ± 0.41	0.05 ± 0.08
Great Tit Parus major	0.05 ± 0.12	0.30 ± 0.05	0.19 ± 0.04	25.9***	0.51 ns	0.17 ± 0.04	0.63	0.87
	0.05 ± 0.02	0.26 ± 0.04	0.18 ± 0.22
Chaffinch Fringilla coelebs	0.07 ± 0.02	0.24 ± 0.05	0.23 ± 0.08	12.2*	0.5 ns	0.18 ± 0.02	0.55	0.80
	0.09 ± 0.03	0.23 ± 0.06	0.23 ± 0.08
Blackcap Sylvia atricapilla	0.25 ± 0.10	0.21 ± 0.06	0.03 ± 0.02	5.4 ns		0.22 ± 0.02	0.54	0.79
	0.25 ± 0.09	0.27 ± 0.06	0.11 ± 0.04
Blackbird Turdus merula	0.07 ± 0.03	0.35 ± 0.07	0.02 ± 0.02	12.5*	2.38 ns	0.17 ± 0.05	0.53	0.77
	0.17 ± 0.08	0.29 ± 0.07	0.15 ± 0.04
Dunnock Prunella modularis	0.12 ± 0.05	0.25 ± 0.13	0.29 ± 0.17	2.9 ns		0.19 ± 0.03	0.51	0.76
	0.10 ± 0.07	0.20 ± 0.09	0.15 ± 0.04
Garden Warbler Sylvia borin	0.17 ± 0.14	0.07 ± 0.20	0.08 ± 0.08	0.6 ns		0.11 ± 0.05	0.42	0.66
	0.07 ± 0.20	0.17 ± 0.14	0.08 ± 0.08
GS Woodpecker Dendrocopus major	0.14 ± 0.07	0.03 ± 0.03	0.07 ± 0.04	1.90 ns		0.10 ± 0.02	0.30	0.51
	0.09 ± 0.06	0.15 ± 0.13	0.11 ± 0.05

Figure 1. The mean number (± 1 se) of fledged broods encountered per visit to each wood by week; resident species and migrant species. Species occurring in all six woods. See Table 3.

Figure 2. The mean number (± 1 se) of fledged broods encountered per visit to each wood by week; Thrushes and Wren.

Figure 3. The mean number (± 1 se) of fledged broods encountered per visit to each wood by week; Long-Tailed Tits and other tit species.

Figure 4. The mean number (± 1 se) of fledged broods encountered per visit to each wood by week; Treecreepers and Nuthatches combined and Chaffinches.

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