Planning your visit

An online BBS route map

Getting started

Your RO will give you the grid reference of your 1-km BBS square and will provide forms and instructions.

To find the location of your square you can use the Ordnance Survey website. Entering the grid reference in the 'Locate' box will place the marker at the bottom left corner of your square (select the leisure' button to view the National Grid).


and are for taking notes in the field, to be submitted via the BBS-Online recording system.


Count Summary

Count Summary (PDF, 267.24 KB)

Mammal Summary

Mammal Summary (PDF, 169.90 KB)
forms (if sent) are to be used if you submit data on paper. Your RO will provide a map of your survey route, showing two 1-km transects divided into ten 200-m sections (numbered 1 – 10).

Please ensure the route you follow is the same as in previous years, as consistency is essential. If your square has not been surveyed before please refer to the guidance on establishing a new route, and submit a route map to the BTO. If you need to change your route, please check with your RO first, then follow the same procedure as for a new route. You may need to ask permission to access private land on your square, and a standard letter requesting access can be obtained from the BTO or your RO.

All BBS squares are valuable, even those that may appear poor for birds. We would be very pleased if you were to consider your square a long-term project.

Please read the leaflet ‘

, available from your RO or the BBS website.

When to visit

Please make two visits to your BBS square to survey birds (known as your Early and Late visits).

March Optional reconnaissance visit to set up or check transect route and access
Early April – mid May Early season BBS visit
Mid May – late June Late season BBS visit, at least four weeks after your Early visit
April – August Enter data on BBS-Online or return completed forms to your RO

Your Early and Late season BBS visits follow the same procedure, and should be at least four weeks apart. Visits should ideally start between 6 am and 7 am, and no later than 9 am. 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). Consistency is important so please make your visits at around the same time and date each year. 


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

Cloud cover Rain Wind Visibility
0 – 33% - 1 None - 1 Calm - 1 Good - 1
33 – 66% - 2 Drizzle - 2 Light - 2 Moderate - 2
66 – 100% - 3 Showers - 3 Breezy - 3 Poor - 3

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