Breeding Bird Survey

The BTO/JNCC/RSPB Breeding Bird Survey

The Breeding Bird Survey (BBS) is the main scheme for monitoring the population changes of the UK’s common breeding birds.

Thousands of volunteer birdwatchers make standardised counts on randomly-located sites during the breeding season, enabling us to monitor changes in numbers of over 100 widespread bird species. BBS bird population trends are widely used for bird research and conservation.

This long-running survey compares standardised annual counts from randomly- located 1-km squares to measure changes in numbers of widespread birds.


Download forms and instructions

Further information, and answers to frequently asked questions, can be found on the BBS website:

The 2013 breeding season will be upon us and I shall be allocating 1 km squares and sending out paperwork.  If you wish to take part in this survey please make contact with me

Telephone: 01473 721486

Some information on BBS

I will allocate the grid reference of your chosen 1-km BBS square (e.g. TL1234). Please survey the square that is assigned to you, as we cannot use data from other (non BBS) squares.

You may need to ask permission to access private land on your square, and a standard letter requesting access can be obtained from BTO or your RO. Please note that squares that contain few species are just as valuable as those with many species, so it is important not to reject squares on the grounds that they appear uninteresting.

The most valuable information comes from squares that are surveyed by the same person over a number of years, as this consistency allows bird numbers to be accurately compared. We would therefore be pleased if you could consider your BBS square a long-term project.


Once you have been allocated a square, your RO will send you a set of BBS recording forms (one set for each square you have agreed to survey). A full set of forms consists of:

  • 1 set of BBS Instructions (yellow)
  • 1 Habitat Recording Form (green)
  • 2 Field Recording Sheets (white)
  • 1 Mammal Count Summary Sheet (pink)
  • 2 Count Summary Sheets (white)

The Field Recording Sheets and Habitat Recording Form are for taking notes in the field, to be entered directly from these forms to the online recording system, BBS-Online. Please enter your data online if possible, but if you would prefer to return paper forms, please transfer your bird and mammal notes to the Count Summary Sheets, and return all forms.


If your square has been surveyed before, your RO will provide a map of the route taken by the previous observer (also available via BBS-Online), showing the two 1-km transects which are divided into ten 200m transect sections (1 – 10).

Please ensure that the route you follow is the same as in previous years, as consistency is essential. If the route needs to be changed, please consult your RO, and return a map of the altered route (or change the online route map). For instructions on how to establish a new route (for a square that has not been previously surveyed) please see overleaf.


  • March: Optional visit to set up or check transect route and access, and record habitat
  • Early April – mid May: Early BBS visit
  • Mid May – late June: Late BBS visit
  • July – August: Enter data on BBS-Online or return completed forms to your RO

Your Early and Late BBS visits follow the same procedure, and should be at least four weeks apart. Visits should ideally start between 6am and 7am, and no later than 9am. Try to avoid the period of peak bird activity around dawn, and the period of lower activity from late morning onwards (though start times can be later in less accessible areas, if necessary). Consistency is important, so please make your visits at around the same date each year, and around the same time each visit.


Please do not survey birds in persistent heavy rain, very poor visibility or strong wind. Please record weather conditions in the relevant boxes on the forms, using the codes shown below. If the conditions change during your survey visit, please select the single category that best represents the overall conditions.


Using the Field Recording Sheets, record all birds you see or hear as you walk along your two transects at a slow, methodical pace (except juveniles – see next page). You can pause to scan for birds, but should not stop for long periods. As a rough guide, each 1-km transect should take around 45 minutes.

  • Record birds in the appropriate 200m transect section (1 – 10), as shown on your route map. Each transect section is shown as a separate box on the Field Recording Sheet.
  • Please use the standard two-letter BTO species codes, shown on the back of the Field Recording Sheets. If a species is not listed, please give the full name.
  • Record all birds to the sides of your transect line, even if they are in adjacent squares. Don’t record birds that are behind you as you start a transect, or beyond the end of the transect as you finish.
  • Don’t record the same bird twice, e.g. a Mistle Thrush heard singing from several transect sections should be recorded once, where it was first detected. If a bird is at the boundary of two transect sections, record it in one or the other, but not both.
  • There is no need to record the activity or sex of the birds.
  • Please record feral species.
  • Note the start and finish times of each transect, and remember to make a note of the date.


Please record birds in one of the following distance bands, according to where they are when first noted:

  1. Within 25 metres either side of the transect line.
  2. Between 25 and 100 metres either side of the line.
  3. More than 100 metres either side of the line, including birds outside the 1-km square boundary.
  4. Birds in flight only, at any distance. Record by marking the species code with an arrow, e.g. BZ


Birds that can be positively identified as juveniles (birds of the current year) should not be counted. In mixed flocks of adults and juveniles (e.g. Starlings), give your best estimate of how many adults were present.


Birds nesting in colonies within the square (e.g. Rooks, Sand Martins, gulls) will not be adequately monitored using the standard method, and we ask volunteers to count or estimate the number of pairs in the whole 1-km square.

Colony counts should be carried out separately from your transect counts, and it doesn’t matter if individual birds are counted during both the colony and transect counts. Please record as normal all adult birds seen while walking your transects, even if they are at a colony.


Please enter your records online, if possible, as this reduces errors and makes processing data more efficient.


If you are sending in paper forms, please complete the Count Summary Sheets (one for each visit) as soon as possible after each field visit. Simply transfer the number of individual birds recorded in each 200m transect section (1 – 10), in each distance band, for each species. You will need to add up the counts of the same species in the same distance band in the same transect section.


Either enter your records on BBS-Online as soon as possible after completing each survey visit, or return all paper forms to your RO as soon as possible after your final visit (including the Field Recording Sheets). Your completed forms, or online submission, will be acknowledged once received at BTO HQ.

The annual BBS Report is sent to all volunteers who contributed to the survey in that year, containing BBS results and information about research using BBS data. The report is produced and sent out in the year following the fieldwork.

The name and address details of BBS observers will be kept on a computerised database for the purpose of BBS administration, and for furthering the BTO’s objectives. The Data Controller is the Director of Services, BTO, The Nunnery, Thetford, Norfolk, IP24 2PU.

Finally, thanks again for volunteering for the BBS, and we hope that you enjoy taking part in the survey!