BTO - Breeding Birds of the Wider Countryside

GARDEN WARBLER
Sylvia borin

Conservation listings

Unlisted/Green
Biodiversity Steering Group Conservation Concern List

Long-term trend

UK: Fluctuating with no long-term trend

Status summary

Garden Warbler abundance has varied in parallel, to some extent, with that of other trans-Saharan migrant warblers (Siriwardena et al. 1998b), probably reflecting the influence of the environment on the wintering grounds. Despite large short-term fluctuations in abundance, the CBC, CES and BBS all suggest long-term population stability. Productivity, measured by the CES, has declined recently.

Table of population changes for Garden Warbler

Source Period
(yrs) Years Plots
(n) Change
(%) Lower
limit Upper
limit Alert Comment

CBC all habitats 31 1968-1999 85 10 -20 59

25 1974-1999 89 60 22 115

10 1989-1999 93 1 -11 17

5 1994-1999 99 15 4 28

CBC farmland 31 1968-1999 27 0 -48 61

25 1974-1999 27 84 12 227

10 1989-1999 33 3 -24 36

5 1994-1999 35 30 10 64

CBC woodland 31 1968-1999 45 -5 -42 75

25 1974-1999 48 38 -7 118

10 1989-1999 51 -6 -19 10

5 1994-1999 53 6 -7 19

CES adults 15 1984-1999 67 -8 . .

10 1989-1999 79 -3 . .

5 1994-1999 83 -3 . .

CES juveniles 15 1984-1999 65 -29 . . [>25*]

10 1989-1999 75 -7 . .

5 1994-1999 79 -22 . .

BBS UK 6 1994-2000 373 -5 -16 8

BBS England 6 1994-2000 306 -8 -19 6

BBS Wales 6 1994-2000 50 -3 -29 33 Small sample

The Breeding Bird Survey is jointly funded by BTO, JNCC and RSPB

Table of productivity information

Variable Period
(yrs) Years Mean
annual
sample Trend Predicted
in first year Predicted
in last year Change Comment

Clutch size 31 1968-1999 17 None Small sample

Brood size 31 1968-1999 26 None Small sample

Daily failure rate (eggs) 31 1968-1999 23 None Small sample

Daily failure rate (chicks) 31 1968-1999 20 Linear increase 0.0096 nests/day 0.0236 nests/day 0.014 nests/day Small sample

Laying date 31 1968-1999 22 None Small sample

Percentage juveniles (CES) 15 1984-1999 79 Smoothed trend 167 productivity index 100 productivity index -40%[>25*]

Percentage juveniles (CES) 10 1989-1999 92 Smoothed trend 125 productivity index 100 productivity index -20%

Percentage juveniles (CES) 5 1994-1999 96 Smoothed trend 146 productivity index 100 productivity index -32%[>25*]

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This report should be cited as:
Baillie, S.R., Crick, H.Q.P., Balmer, D.E., Beaven, L.P., Downie, I.S., Freeman, S.N., Leech, D.I., Marchant, J.H.,
Noble, D.G., Raven, M.J., Simpkin, A.P., Thewlis, R.M. and Wernham, C.V. (2002) Breeding Birds in the Wider
Countryside: their conservation status 2001. BTO Research Report No. 278. BTO, Thetford. (http://www.bto.org/birdtrends)

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