Garden Warbler

Garden Warbler

Sylvia borin
Garden Warbler, Colin Brown

Introduction

Garden Warbler is one of Britain's most nondescript birds earning it the true moniker of little brown job.

A warbler of dense scrub understorey and woodland edge, the Garden Warbler is more often noticed in well-wooded countryside rather than in gardens. It is evenly coloured brown with beige underparts, and has a stout black bill and beady black eye. Garden Warblers spend our winter months south of the Sahara.

The Garden Warbler comes into its own when it sings, with rich, fluty whistling notes. In addition to its lack of a black cap, to the practised ear its song distinguishes Garden Warbler from the commoner and more widespread Blackcap.

  • Our Trends Explorer gives you the latest insight into how this species' population is changing.
Garden Warbler, Colin Brown

Key Stats

Status
Common
Common
Weight
Weight
17.2g
Eggs
Eggs
4-5
BTO Records
BTO Records
200k records
Population and distribution stats for:
Population Change
Population Change
Stable 1967 to 2023
Population Size
Population Size
145k territories
Distribution Change
Distribution_change
12.6% expansion
Population Size
Population Size
No current data
Distribution Change
Distribution_change
33.3% expansion

Identification

Curated resources to aid in the identification of Garden Warbler

ID Videos

This section features BTO training videos headlining this species, or featuring it as a potential confusion species.

#BirdSongBasics: Blackcap and Garden Warbler

Warbler Identification Workshop Part 2: Blackcap & Garden Warbler

Songs and Calls

Listen to example recordings of the main vocalisations of Garden Warbler, provided by xeno-canto contributors.

Song:

Call:

Alarm call:

Movement

Information about Garden Warbler movements and migration based on online bird portals (e.g. BirdTrack), Ringing schemes and tracking studies.

Britain & Ireland movement

View a summary of recoveries in the Online Ringing Report

Foreign locations of birds ringed or recovered in Britain & Ireland

Dots show the foreign destinations of birds ringed in Britain & Ireland, and the origins of birds ringed overseas that were subsequently recaptured, resighted or found dead in Britain & Ireland. Dot colours indicate the time of year that the species was present at the location.

  • Winter (Nov-Feb)
  • Spring (Mar-Apr)
  • Summer (May-Jul)
  • Autumn (Aug-Oct)
Foreign locations of birds ringed or recovered in Britain & Ireland

European movements

EuroBirdPortal uses birdwatcher's records, such as those logged in BirdTrack to map the flows of birds as they arrive and depart Europe. See maps for this species here.

The Eurasian-African Migration Atlas shows movements of individual birds ringed or recovered in Europe. See maps for this species here.

Biology

Lifecycle and body size information for Garden Warbler, including statistics on nesting, eggs and lifespan based on BTO ringing and nest recording data.

Productivity and Nesting

Nesting timing

Average (range) fo first clutch laying dates
21 May (8 May-21 Jun)
Typical (exceptional) number of broods
1(2)

Egg measurements

Typical length x width
20x15 mm
Mass (% shell)
2.2g (6%)

Clutch Size

Typical number
4-5 eggs
Average ±1 standard deviation
4.32±0.71 eggs
Observed minimum and maximum
2-6 eggs

Incubation

Incubation by
Male + Female
Typical duration
10-12 days
Observed average ±1 standard deviation
11.3±1.22 days
Observed minimum and maximum
9.5-13.5 days

Fledging

Type of chick
Altricial, naked
Typical duration
11-12.5 days
Observed average ±1 standard deviation
11.52±1.19 days
Minimum and maximum
9-13 days
N=869, -Source
Visit our Trends Explorer for trend graphs and country statistics.

Survival and Longevity

Survival is shown as the proportion of birds surviving from one year to the next and is derived from bird ringing data. It can also be used to estimate how long birds typically live.

View number ringed each year in the Online Ringing Report.

Lifespan

Typical life expectancy of bird reaching breeding age
2 years with breeding typically at 1 year
Maximum age from a ringed bird
10 years, 1 month, 6 days (set in 2015)

Survival of adults

All adults
0.5±0.045

Survival of juveniles

All juveniles
0.265±0.045 (in first year)
Visit our Trends Explorer for trend graphs and country statistics.

Biometrics

Wing length and body weights are from live birds (source).

Wing length

Average ±1 std deviation; range and sample size in brackets.
Juvenile
77±2.1 mm
(74-81 mm, N=8124)
All adults
77.9±2 mm
(75-81 mm, N=6566)
Female
77.7±1.9 mm
(75-81 mm, N=1859)
Male
78±2.1 mm
(75-81 mm, N=1017)

Body weight

Average ±1 std deviation; 5th and 95th percentiles and sample size in brackets.
Juvenile
18.5±2.3 g
(15.4-23 g, N=7512)
All adults
17.2±1.6 g
(15.2-20.4 g, N=5834)
Female
17.5±1.6 g
(15.4-20.5 g, N=1612)
Male
16.7±1.1 g
(15.2-18.5 g, N=894)
Visit our Trends Explorer for trend graphs and country statistics.

Ring Size

A (pulli B)

Classification, names and codes

Taxonomy, names and species codes for Garden Warbler

Classification and Codes

  • Order: Passeriformes
  • Family: Sylviidae
  • Scientific name: Sylvia borin
  • Authority: Boddaert, 1783
  • BTO 2-letter code: GW
  • BTO 5-letter code: GARWA
  • Euring code number: 12760

Alternate species names

  • Catalan: tallarol gros
  • Czech: penice slavíková
  • Danish: Havesanger
  • Dutch: Tuinfluiter
  • Estonian: aed-põõsalind
  • Finnish: lehtokerttu
  • French: Fauvette des jardins
  • Gaelic: Ceileiriche-gàraidh
  • German: Gartengrasmücke
  • Hungarian: kerti poszáta
  • Icelandic: Garðsöngvari
  • Irish: Ceolaire Garraí
  • Italian: Beccafico
  • Latvian: darza kaukis
  • Lithuanian: sodine devynbalse
  • Norwegian: Hagesanger
  • Polish: gajówka
  • Portuguese: toutinegra-das-figueiras
  • Slovak: penica slávikovitá
  • Slovenian: vrtna penica
  • Spanish: Curruca mosquitera
  • Swedish: trädgårdssångare
  • Welsh: Telor yr Ardd
  • English folkname(s): Pettychap

Research

Interpretation and scientific publications about Garden Warbler from BTO scientists.

Causes of Change and Solutions

Causes of change

The causes of change in Garden Warbler abundance are unclear, but the decline is most likely to be driven by reduced productivity or juvenile survival.

Further information on causes of change

Garden Warbler abundance has varied alongside that of other trans-Saharan migrant warblers (Siriwardena et al. 1998b), probably reflecting the influence of changes in their winter environment. Despite large short-term fluctuations in abundance, the CBC/BBS data suggest that the population may be in long-term decline. Analysis of annual population changes and winter survival estimates across western Europe shows only a weak relationship between survival and population change, suggesting than long-term population change may be driven by reduced productivity or juvenile survival (Johnston et al. 2016). CES survival rates for adults have decreased, and there have been increases in nest failure rates and corresponding declines in the number of fledglings per breeding attempt. Post-fledging productivity, as measured by the CES, has also declined sharply since 1983. The negative effects of deer browsing are particularly strong for Garden Warbler (Holt et al. 2011) and hence a reduction in understorey habitat could potentially be a factor which has contributed towards the observed trends, though this has not been confirmed.

Information about conservation actions

The main drivers of change for Garden Warbler are not known and may possibly reflect changes during winter, but productivity may play a role and therefore conservation actions to improve breeding habitat could benefit this species. Mustin et al. (2014) found that the change in vegetation cover at 0.5 to 2 m above ground was the most important factor determining colonization or extinction by Garden Warbler, and suggested that habitat creation could help counteract possible future effects of future climate change.

The importance of understorey habitat to this species is also highlighted by another study which looked at the effects of deer browsing on bird species. The negative effects of deer browsing were particularly strong for Garden Warbler (Holt et al. 2011) and therefore actions to control deer numbers or exclosures to exclude deer are likely to help provide understorey habitat for this species, as well as other actions to encourage the growth of shrub layer vegetation.

Publications (2)

Breeding periods of hedgerow-nesting birds in England

Author: Hanmer, H.J. & Leech, D.I.

Published: Spring 2024

Hedgerows form an important semi-natural habitat for birds and other wildlife in English farmland landscapes, in addition to providing other benefits to farming. Hedgerows are currently maintained through annual or multi-annual cutting cycles, the timing of which could have consequences for hedgerow-breeding birds. The aim of this report is to assess the impacts on nesting birds should the duration of the management period be changed, by quantifying the length of the current breeding season for 15 species of songbird likely to nest in farmland hedges. These species are Blackbird, Blackcap, Bullfinch, Chaffinch, Dunnock, Garden Warbler, Goldfinch, Greenfinch, Linnet, Long-tailed Tit, Robin, Song Thrush, Whitethroat, Wren and Yellowhammer.

05.03.24

BTO Research Reports

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Birds of Conservation Concern Wales 4: the population status of birds in Wales

Author: Johnstone, I.G., Hughes, J., Balmer, D.E., Brenchley, A., Facey, R.J., Lindley, P.J., Noble, D.G. & Taylor, R.C.

Published: 2022

The latest review of the conservation status of birds in Wales. The report assessed all 220 bird species which regularly occur in Wales. There are now 60 species of bird on the Red List, with 91 on the Amber List and just 69 - less than a third of the total number of species - on the Green List. The latest review of the conservation status of birds in Wales comes 20 years after the first, when the Red List was less than half the length it is today. The report assessed all 220 bird species which regularly occur in Wales. There are now 60 species of bird on the Red List in Wales, with 91 on the Amber List and 69 on the Green List. The Birds of Conservation Concern in Wales report assesses the status of each species against a set of objective criteria. Data sources include the BTO/JNCC/RSPB Breeding Bird Survey and the BTO/RSPB/JNCC Wetland Bird Survey, as well as Bird Atlases and other BTO-led monitoring schemes and citizen science initiatives. These are used to quantify the changing status of the species’ Welsh population. The UK, European and global conservation status of the species is also considered, placing the Welsh population into a wider context. The Red ListSwift, Greenfinch and Rook – familiar breeding species in steep decline across the UK – are among the new additions to the Welsh Red List, which now also includes Purple Sandpiper, on account of a rapidly shrinking Welsh wintering population, and Leach’s Petrel, an enigmatic seabird in decline across its global range. These species now sit alongside well-known conservation priorities, such as Curlew, Hen Harrier and Turtle Dove as birds at risk of being lost from Wales for good. Uplands and woodlands Many of the species on the Red List are found in upland and farmland habitats. Starling, Tree Sparrow, Yellow Wagtail and Yellowhammer can no longer be found in much of Wales, while iconic species of mountain and moorland, such as Ring Ouzel, Merlin and Black Grouse, remain in serious trouble. Wales is well known for its populations of woodland birds; however, many of these – including Lesser Spotted Woodpecker, Willow Warbler and Spotted Flycatcher – also feature on the Red List. Goldcrest, which has seen its Welsh population shrink alarmingly in recent decades, is another new addition. On the coast The assessment for Birds of Conservation Concern Wales 4 took place before the impacts of avian influenza could be taken into account. Breeding seabird species have been struggling in Wales for many years, however, and most were already of conservation concern before the outbreak of this disease. Kittiwake, Puffin, Black-headed Gull, and Common, Arctic and Sandwich Tern remain on the Red List. Wales holds internationally significant numbers of breeding seabirds, making the decline of these colonies a global concern. The Amber ListDeclines in Wheatear, Garden Warbler and House Martin - all migrants which breed in Europe and winter in sub-Saharan Africa - mean these species have moved from the Green List to the Amber List. Many other ‘Afro-Palearctic' migrant species are also in decline, but the potential reasons for this, such as habitat loss and reduced availability of invertebrate prey, are not well understood. Closer to home, the declines in the Welsh Chaffinch population, linked to the disease trichomonosis, have seen the species Amber-listed. A number of other species have been placed on the Amber List because of the wider importance of their Welsh populations, which in each case make up more than half the UK total. Wales is home to more than three-quarters of the UK’s Choughs, for example, so recent declines are cause for concern. The nation’s breeding populations of Manx Shearwater, Pied Flycatcher, Goshawk and Hawfinch also account for more than half the UK total, as does its wintering population of Spotted Redshank. It’s not all bad news, though: some species now on the Amber List have moved up from the Red List, indicating some positive change in their population trends. These include Common Sandpiper, Great Black-backed Gull, Bullfinch, Goldcrest and Pied Flycatcher. The Green ListWhile the report contains much cause for alarm, several conservation success stories shine through. Red Kite was almost lost as a British bird during the first half of the 20th century, when only a handful of pairs remained in remote Welsh valleys. Since then, a sustained conservation effort has brought the species back from the brink. Wales is now home to more than 2,500 pairs of Red Kite and the species has now been moved to the Green List, reflecting this incredible change in fortunes. Song Thrush, Reed Bunting, Long-tailed Tit, Redwing and Kingfisher are among the other species to have gone Green, providing much-needed hope that things can go up as well as down.

06.12.22

Reports Birds of Conservation Concern

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More Evidence

More evidence from Conservation Evidence.com

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