BTO Breeding Bird Survey: latest news

Government restrictions meant that most BBS volunteers this year were unable to complete their early-season visits which would normally be made between the beginning of April and the middle of May. Fortunately, the easing of restrictions on May 13th allowed many volunteers to complete their late-season visits, and results have been submitted for 125 squares in Sussex this year. BTO staff will be working hard to analyse the data this year in a way that makes allowance for the missing early-season results. Many thanks are due to all those volunteers who have been able to make late-season visits, and also to those volunteers who have been unable to survey their squares at all this year but who are looking forward to resuming the BBS as normal next year.

Trend graphs plotted for 36 common species using Sussex BBS data including data from 2019 are available here; these can be compared with national and regional trend graphs available at The trend graphs are plotted using the percentage changes each year since the start of the survey in 1994, presented as indices relative to an arbitrary index of 1.0 in 1994. Some of the graphs inevitably show significant declines in species populations. Most people know that greenfinch population levels have declined in recent years, but a steady decline in chaffinch population levels has perhaps been less widely appreciated. In contrast, house sparrow population levels in Sussex appear to be relatively stable, and goldfinch population levels in Sussex are clearly increasing at a significant rate.

Now is a good time of the year to consider taking part in the BBS, because if you take on a square you will also have the option to take part in the Sussex Winter Bird Survey (SWBS) by surveying the same square over the coming winter.

The BBS is a national monitoring scheme administered by the BTO and jointly funded by the BTO, JNCC and RSPB. It has been running since 1994 and its primary aim is to provide population trends for common and widespread bird species in the UK. Population trends for Sussex are also produced annually. Survey plots are randomly-selected 1-km squares of the National Grid, and the same squares are surveyed each year. Volunteers visit their squares three times each year during the breeding season, once to record simple habitat data, and twice to walk a fixed route, recording birds seen and heard. There are more than 200 BBS squares across Sussex, covering every type of habitat, and new volunteers are always needed. Volunteers must be able to recognise common and widespread birds, but previous experience of survey work is not necessary. Help and support from experienced volunteers can be arranged if required, and some informal group practice sessions will hopefully be planned for March 2021 to which new volunteers will be invited.

The BBS squares (asterisks indicate priority squares that have been surveyed before) in Sussex which currently need volunteers for the 2021 breeding season (updated 26/1/2021) are:

SU8612 West Dean
SU8624 Tote Hill near Midhurst
SU8926 Henley Common
SU9017 Heyshott*
SU9113 near East Dean*
SU9216 Graffham Down*
SU9228 near Blackdown*
SU9705 Walberton*
SU9915 near Bignor
SZ7996 East Wittering*
SZ8199 near Birdham
TQ0124 near Kirdford*
TQ0502 Rustington
TQ1323 Dragon’s Green
TQ1917 near Bines Green
TQ2536 Gossops Green
TQ2721 near Goddards Green*
TQ2817 Hurstpierpoint*
TQ3122 near Haywards Heath*
TQ4136 Ashurst Wood*
TQ4738 near Blackham*
TQ4806 Firle Beacon*
TQ4938 near Blackham*
TQ5026 High Hurstwood
TQ5130 central Crowborough
TQ5228 near Crowborough*
TQ5435 near Eridge Station*
TQ5514 near Chiddingly
TQ5738 Tunbridge Wells*
TQ6000 Eastbourne Upperton
TQ6313 near Herstmonceux
TQ6414 Bodle Street Green*
TQ6419 Earl’s Down*
TQ6724 Burwash*
TQ7028 near Hurst Green
TQ8013 Baldslow*
TQ8413 near Three Oaks
TQ8518 Udimore*
TQ8613 Guestling Green
TQ8722 Peasmarsh

For further information about the BBS, please contact:
Helen Crabtree
BTO Representative for Sussex
Phone: 01444 441687

For further information about the Sussex Winter Bird Survey, please contact:
Christine George