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Thank you for volunteering to take part in the Breeding Bird Survey (BBS), a scheme designed to keep track of breeding bird populations in the UK. The survey is designed to be a quick, simple and, most importantly, an enjoyable birdwatching exercise. Plots are 1x1-kilometre (km) squares of the National Grid. Observers make just three visits to specially selected squares, the first to record habitat types and to set up a suitable survey route, and the second and third to record birds that are seen or heard while walking along the route. These instructions can be used by both the BBS Online user (volunteers who will be entering their data via the Web) and the paper form user. Main aims The main aims of the BBS are:
Paper forms to receive Once you have contacting your Regional Organiser and have been allocated a randomly selected 1-km grid square, you should receive the following paper forms in the post (one set of forms for each square you have agreed to cover): 1 x Breeding Bird Survey Instructions booklet (yellow) We recommend that both the BBS Online and paper form user take the Field Recording Sheets, Habitat Recording Form and Mammal Count Summary Sheet out in the field to record their sightings on. Only the paper form user needs to transfer their bird count records from the Field Recording Sheet to the Count Summary Sheet. The BBS Online user enters their bird count data from the Field Recording Sheet directly on to BBS Online. Organisation The BBS is organised through the BTO's network of voluntary Regional Organisers (ROs), most of which are also BTO Regional Representatives. The UK is divided up into 124 BTO regions, defined primarily by 10km grid squares. Each BTO region has an RO assigned to it, and it is their responsibility to allocate you a BBS square and to issue and collect in completed forms. All completed forms should be sent direct to the RO. The RO will also be able to deal with any questions you have about BBS methodology and land access issues. For answers to Frequently Asked Questions, please refer to our FAQ web page. If your BTO region does not have an RO, the National Organiser Mike Raven, will act as your RO and all completed forms should be sent to him at BTO HQ in Thetford. The National Organiser and other BTO staff from the Census Unit will be happy to deal with any questions you have regarding the survey. Which square should you survey? Either your RO or National Organiser will have provided you with the Ordnance Survey (OS) grid reference of the 1-km square we would like you to survey. Grid references are in standard OS format (i.e. two letters for the 100-km square, two numbers representing the 'easting' and two numbers representing the 'northing'). Please check carefully the reference of the square you have been allocated. Squares have been chosen according to a formal sampling strategy to cover all habitats and regions. Comprehensive coverage is vital to the survey design. Please make every effort to cover the square that is assigned to you. We will not be able to use data collected from additional or substituted squares. In cases where survey work proves impossible in a large part of the square you have been allocated, e.g. because it is physically impossible to visit or access permissions are not granted, please report this to your RO immediately so that a replacement square can be provided. It is very important not to reject squares on the grounds that they appear uninteresting - squares containing few species are just as valuable as squares with many species. For squares containing a large area of water, estimate how many of the 10 ideal transect sections are located on dry land (above Mean High Water). If this is less than 4 (i.e. less than 800m of transect) regard the square as 'uncoverable' and report it to Census Unit via your RO.
Finding and marking a route If the square has been surveyed before, your RO should provide you with a sketch map of the counting route (the transect line) taken by the previous BBS observer. This route must be followed to ensure consistency of recording on that square (i.e. if a different route is taken, different birds will probably be recorded). If the route has to be changed because you can no longer get access to it, please consult your RO and return the completed Habitat Recording Form, with a sketch map of the new route on it. If, and only if the square has never been covered before (your RO will tell you this), will you need to create your own transect route across it. The transect line through the square should ideally consist of two parallel lines, north-south or east-west, each 1-km long. Please ensure that the route followed is the same as in previous years. Transect lines should be 500 metres (m) apart and 250m in from the edge of the square. Each transect line should be divided into 5 equal sections of 200m in length, making a total of ten (2x5), numbered 1 to 10. It is important to note the starting points of each transect section either by using permanent landmarks (trees, hedges, boulders, houses etc) or by using temporary markers (coloured tape or cord etc). Figure 1 - Transect route
In practice, your transect lines are likely to deviate from the 'ideal' because of problems with access, or barriers such as roads, rivers, and canals: possible solutions are given below. Once you have decided upon a route, it is of the greatest importance that the same route is followed year after year. In cases where the transect lines deviate considerably from the 'ideal', at no point should the two lines be closer together than 200m. Minor intrusions into adjacent squares are perfectly acceptable and may provide the only practical way to carry out the survey. Please record the exact route taken in the box provided on the green habitat form. Figure 2 - Examples of transect route
When to visit The main part of the breeding season, roughly between 1st April and 30th June, in the lowlands of southern Britain, should be divided into two counting periods (early season visit = April to mid-May; late season visit = mid-May to late June) and one visit should be made in each half. Visits should be at least 4 weeks apart. The first should coincide with the main activity period of the resident breeding birds in an area, while the second should take place after the arrival of the latest migrant breeding birds. Where local conditions dictate, for example, at higher altitudes or further north, visits should be shifted later in the season, but the final transect count should be completed by mid-July. From late-June, counts will almost certainly include a much greater proportion of unidentified young birds, and most species will have reduced or stopped singing. Counts should be made during the morning, beginning ideally between 6am and 7am, and no later than 9am. Please try to keep the starting times similar within a breeding season and across years, preferably to within half-an-hour. Please also try to keep the visit dates similar across the years. Counts will be more productive earlier in the day, with birds generally becoming quiet and inactive from late morning until mid afternoon (11am to 3pm). Starting times can be shifted to begin later in more remote and less accessible areas. If survey times extend beyond midday please use the 24-hour clock. Weather Please do not attempt to census birds in conditions of heavy rain, poor visibility or strong wind. Birds generally become inactive and quiet in windy and wet conditions, although activity often increases considerably after rain showers and therefore showery weather is generally okay to conduct a survey in. Bird activity also becomes quieter earlier in the day if there have been several previous days of fine weather, so an earlier start is therefore advisable. Please record weather conditions in the boxes provided on the forms that describe cloud cover, rain, wind speed, and visibility. Choose one number (1-3) from each of the four headings below and enter these in the box provided on the Field Recording Sheets. If the weather conditions change halfway through your survey, then record the mid-point; e.g. if cloud cover = 1 at the start of your survey visit and 3 at the end, then record 2.
Recording birds Please record all the birds you see or hear as you walk along the two linear transects. Birds should be noted in the appropriate distance category, measured at right angles to the transect line. Do not record birds that are behind you as you begin a census or beyond the end of the transect. From your chosen starting point, begin to walk the first half of your transect route at a slow and methodical pace. We recommend that you pause briefly to listen for bird songs and scan for birds flying overhead. Please remember to note the starting and finishing times of each transect (using a 24-hour clock, e.g. 0630, six-thirty in the morning, 1300, one o'clock in the afternoon). As a guide an average visit should last around an hour and a half. Record all the birds you see and hear on the Field Recording Sheets in the appropriate transect sections 1-10 and in the appropriate distance category (see below). Birds should be recorded in one of the following four categories when they were first noted: 1. within 25 metres either side of the line; The transect is divided into 200m sections for convenience; please don't worry about birds at the boundary of two sections: record them in the one that seems more appropriate, but not in both. At the end of the first half (section 5) of the transect, record the time and break from recording while you make your way to the start of the second half of the transect route. Commence recording again through sections 6-10. Try not to record the same individual bird twice. So for example, a Mistle Thrush that can be heard singing from several transect stretches should be recorded once, where it was first detected. We would strongly encourage observers to use the standard BTO species codes (see Appendix 1). Please familiarise yourself with the most likely codes before you go into the field. If a species is not listed in Appendix 1 please give the full common name. There is no need to record the activity or sex of the birds you encounter, although you may wish to do so. Please distinguish juvenile birds recorded from adults in those species where this is possible (e.g. B.juv, juvenile Blackbird), because counts of juveniles should not be entered onto BBS Online or the Count Summary Sheets. Please also note any feral species on transects. Please note that distances are measured perpendicular to the transect line (i.e. at right angles to the line). A bird seen 200m ahead of the observer but close to the transect line should be recorded in category 1. We recommend that observers measure out distance categories (25m and 100m) using a combination of a tape measure and pacing to familiarise themselves with these before fieldwork begins. Category F, Birds in flight, relates to those flying over. Draw an arrow through the species' two-letter code to indicate that it is in flight. If a bird is seen to take off or land it should be recorded in the appropriate distance category (1-3) at that position. N.B. Skylarks in display flight and hovering Kestrels should be recorded in the relevant distance category. Please record swifts, swallows and martins in the flight category, unless they are seen to land or fly into a nest site, such as a barn or the eve of a roof. If you have difficulty distinguishing adult and young birds, simply estimate to the best of your ability how many adults were present. We appreciate that mixed-aged flocks of crows or Starlings, for example, will present problems later in the season and ask that you observe and record with great care. Colonial nesters should be entered in the box provided at the end of the summary form (paper form users only). Count Summary Sheets Paper form users only:Please complete the Count Summary Sheets (one for each Field Recording Sheet) as soon as possible after each field visit and preferably on the same day. The form summarises the information so that it can be analysed. Simply transfer the number of individual birds (excluding juveniles) that were recorded in each section of the transect, 1-10, on each visit, in each distance band. Print the two-letter species codes in the appropriate boxes (and remember to add a full stop for single letter codes e.g. B. = Blackbird). You may find it helpful to cross through species registrations on the field recording sheet as you transfer this information to the summaries (see page 5). This reduces the chance of duplicating or missing records. Each volunteer is assigned an observer code (Obs. code) by BTO Census Unit when we receive the completed forms - please leave this box blank. Juvenile birds Juvenile birds can be recorded on the Field Recording Sheets, but must NOT be entered onto BBS Online or the Count Summary Sheets. If you have difficulty distinguishing adult and young birds simply estimate, to the best of your ability, how many adults were present. We appreciate that mixed-aged flocks of crows or Starlings, for example, will present problems later in the season and ask that you observe and record with great care. Colonial nesters should be entered separately on BBS Online or in the box provided at the end of the Count Summary Sheet (paper form users only). Colonial nesting birds Birds nesting in dense colonies within the square (Rook, Sand Martin and gulls) will not be adequately censused using the standard method, and we ask observers to count or estimate the number of nests in the whole 1-km square. Colony counts should be conducted separately from the transects, and only for those species listed above. Please do not exclude counts of adult birds seen at these colonies during your normal line-transect counts (i.e. record the number of adults seen during your two line-transect counts as well as the number of active nests counted on your separate colony counts). Example of completed field recording sheet
Example of field recording sheet
Example of Count Summary Sheet
Habitat recording Habitat recording is an essential part of the BBS because it allows changes in bird numbers to be related to changes in habitat available to them. Habitat forms must be completed each year using the coding scheme that is common to a range of BTO projects. This is shown on the back of the green form and can also be seen in Appendix 2. The habitat recording system can be used without specialist knowledge. We advise that habitat details are recorded on your reconnaissance visit or following a count. Please do not record birds and habitat at the same time. Habitat should be recorded separately for each of the 10 transect sections. Please record what you feel to be the most appropriate codes for each section (i.e. the area within a box 200m long by 50m wide). Codes allow you to describe both the predominant habitat, termed the First habitat on the form, and the secondary habitat, termed the Second habitat on the form. In many cases, two habitats will have equal importance and the order they are entered does not matter. For each habitat, choose one habitat code from each of levels 1 and 2, and up to two codes from levels 3 and 4. Please complete as much detail as you feel able: the first two levels are most important. The example below describes an area of arable farmland. Transect 1 comprises tilled land with a hedgerow without trees, an active farmyard, with autumn cereal growing. There is no secondary habitat and so this is left blank. Transect section 2 is a similar area containing woodland. The first habitat codes are the same and the second codes are for woodland i.e. coniferous, young plantation with low disturbance, moderate shrub layer and sparse field layer. Note that the Shrub layer comprises woody plants less than 5m tall and the Field layer comprises herbaceous, non-woody plants. If there is no appropriate code in levels 3 or 4 please put a dash ('-') in that column. Example of completed habitat form
Please note that for squares covered for the first time, we ask for the habitat actually covered and the habitat of the ideal (straight) transects. After the first year, observers can use the more simple form as shown above, recording only the actual habitat details. 'Ideal' transects can be either North to South or East to West, depending on your chosen route. If major habitat changes occur on your square through the course of the survey, these changes should be recorded in the box provided. Please enter the transect number and the new codes. Examples of major habitat change include ploughing of set-aside, introduction or removal of animal stock and tree felling. Recording mammals Mammal Species Codes The 19 most commonly recorded mammal species are printed on the front of the pink Mammal Count Summary Sheet. The BTO's two-digit mammal species code is shown with the name of the mammal. Please list any additional species not listed on the form in the blank rows underneath "61 Feral/Domestic Cat". Please see Appendix 3 for a full list of mammal species codes. Known to be present In addition to mammals seen and counted during the two bird count visits, observers may find other evidence of mammals during these and additional visits to the square. In the ‘Known to be present in square’ column, indicate the method/s by which the mammal species was recorded, using one or more of the following letters: C Live animals seen and counted by yourself during the early or
late visit * this season denotes the period from January to July of this calendar year. Field signs must be current, including active setts, dreys and fox dens. For instance, with badger setts, only use the F (field signs) code if there are signs of recent activity, e.g. a clear sett entrance and spoil heap, presence of footprints, snuffle holes and latrines. Numbers counted on transect (visual records only) The columns headed "Numbers counted on transect (visual records only) / Early and late" are for entering counts of live mammals seen as you carry out your two line transect counts – not for dead animals (D), field signs (F), local knowledge (L), or live animals seen by yourself on additional visits (S). There is no need to make special visits to count mammals and they are not recorded in distance bands. For each species, total the number counted from all ten 200m transect sections for each visit and enter these in the appropriate boxes. If you come across groups of mammals, please make your best estimate of their numbers. An estimate of the numbers of a particular species (no matter how rough), is more useful than recording ‘too many’ etc. Visits made to your square Please tick one of the three boxes indicating the number of visits made to your square during this season (January to July). If you have only visited your square during the three BBS visits (one habitat & two counts) then tick the first box (BBS visits only); if you have made up to three extra visits tick the second box (1-3 extra visits) and if you have made more than three extra visits tick the third box (4 or more extra visits). If you have only managed one or two visits to your square during the season also tick the first box (BBS visits only). You might find it useful to use the white Field Recording Sheets to record your mammal sightings, writing the species name in full and the numbers counted (as you do using two-letter species codes for birds). Counts of mammals should then be transferred from the Field Recording Sheets onto the Mammal Count Summary Sheet. If you have surveyed your square for mammals, but did not see any species during your two transect counts or additional visits, then enter "N" in the "saw no evidence of mammals" box. If you made no attempt to record mammals on your square please enter "X" in this box. Please return the completed Mammal Count Summary Sheet to your Regional Organiser or enter the data on BBS Online. Return of data BBS Online user: Paper form user: Appendix 2. Habitat Coding System Appendix 3. Mammal Species Codes Fieldworkers should not put themselves in a position that could place them, or others, in danger. The Trust does not take any responsibility or liability for any actions and subsequent consequences from the activities of fieldworkers. Please ensure that you have obtained the relevant permission to enter private land over which your transect lines cross. Many thanks for helping with this important project and enjoy your censusing! If you have any queries about BBS please contact
either your BTO Regional Organiser or |
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