Wintering Warbler Survey 2006/07
Six species of warblers can be found regularly wintering in Britain
and Ireland. These include two mainly resident species: Cetti’s
Warbler and Dartford Warbler; plus four mainly migratory species:
Chiffchaff, Blackcap, Firecrest and Goldcrest. In addition, there
are at least ten other species, which occasionally winter. The most
frequent of these are Lesser Whitethroat, Yellow-browed Warbler
and Willow Warbler, occurring almost annually.
Very little is known about the current status of our wintering
warbler populations, at a national level. The most recent population
estimates are given in the BTO winter Atlas 1981-1984, as follows:
Blackcap (3,000), Chiffchaff (500-1,000), Cetti’s Warbler
(500-1000), Dartford Warbler (1,500-1,800), Firecrest (200-400)
and Goldcrest (2-4 million). With the exception of Goldcrest, the
majority of species are distributed along the southern and western
coastal counties, see below, where the winter climate is mildest.
This is particularly true of the Chiffchaff and Firecrest, which
remain entirely insectivorous throughout the winter.
There have been two previous national BTO surveys, which were undertaken
in 1945-1954 and 1978/79 but these only focussed on Blackcap. Between
these two surveys the number of wintering Blackcap showed a substantial
increase. Since the early 1980’s, the number of Blackcap,
Chiffchaff and Firecrest, (as noted in county bird reports) have
all shown further increases. Two major factors associated with the
increases have been the expanding breeding populations together
with a run of mild winters, thus assisting winter survival. Given
the increasing numbers, we now want an up-to-date picture of where
these birds occur during the winter and what numbers are involved.
This new survey will provide a baseline against which to monitor
Many of the Blackcaps wintering in Britain and Ireland breed in
Central Europe, which is a recently adopted migration strategy for
birds that would usually winter around the Mediterranean. As for
Chiffchaff and Firecrest, not a great deal is known as to the exact
populations from which they originate. However, ringing data for
Chiffchaff show that birds from northern Europe across to western
Siberia, all winter in Britain.
The main aims of this survey are to find out how many individuals
spend the winter in Britain and Ireland and collect information
on where they occur. The survey will run for at least two winters,
commencing in November 2004. This will help provide updated population
estimates and a more detailed understanding of where these wintering
In addition, we would also like to collect information on the following
aspects to help understand the actual distributions:
1) Number of each sex (mainly Blackcap)
2) Number of singing individuals
3) The general habitat type in which the bird is situated
4) Food items (mainly for Blackcap)
5) Number of Chiffchaffs with grey plumage (individuals from Eastern
6) Plus any other notes on behaviour.
How to contribute
Survey Period: 1st November 2006 to 31st March
2007 (15th April for Blackcap only)
All records of wintering warblers are required, particularly for
the three key species (Blackcap, Chiffchaff and Firecrest), during
the survey period; Goldcrest is optional due to it’s widespread
distribution. Observations may be consist of daily garden sightings,
casual observations or counts made as part of your regular bird
Other counts are required from the following types of location:
i) gardens, ii) sewage works, iii) wetlands/water bodies, iv) rivers/canals
and v) coastal sites.
Recording your sightings
Records can also be submitted on-line using the BirdTrack website:
birdtrack.net/ . If you
are not already a BirdTrack recorder, register using the link on
the BirdTrack homepage ‘Register for BirdTrack’. To
enter sightings click on the link ‘login to enter sightings’
and set up your sites and records.
A set of instructions and recording form can be
downloaded from the website, see below. Also, an Excel version of
the recording from can be downloaded, in which your observations
can be entered and then returned via email at the end of the winter.
To download the instructions as a .pdf file click
To download a recording form as an Excel spreadsheet (for entering
you records and emailing back at the end of the winter) click
Chiffchaffs. Since December 1999, over 700 wintering individuals have been marked in southern
England as part of a study investigating wintering ecology. Each
bird carries a total of four rings (two on each leg), consisting
of a metal ring and three coloured rings. All sightings are required
to help monitor survival and movements. Please send sightings to Greg Conway (
See the results
You can look at the latest results for Blackcap,
on BirdTrack. These pages have graphs that show the number of records
and the proportion of lists submitted with these species on. To
view the animated maps for these species click here
and select the species you are interested in.
For more information on this survey please contact: Greg Conway,
Wintering Warbler Survey Organiser, BTO, The Nunnery, Thetford,
Norfolk IP24 2PU. Email:
Tel: 01842 750050.