A survey of tetrads known to have been recently occupied by singing Nightingales forms the main part of the survey. We compiled a list of 2,400 such tetrads (2 x 2-km squares of the Ordnance Survey national grid), using the 1999 survey results, subsequent records from Atlas 2007-11 and other sources and with help from BTO Regional Representatives (RRs). A few hundred additional tetrads were added, to test the likelihood that our initial list was incomplete.
RRs were asked to find volunteers to visit every one of the selected tetrads at least twice during the early spring (21 April to 20 May). Each visit was to cover all suitable Nightingale habitat within the tetrad in the early morning and map any singing Nightingales onto a pre-printed survey form. Basic habitat information was requested for any Nightingale territories found.
There are also optional nocturnal visits to occupied tetrads (ideally at least two during 18 May to 4 June). The main aim of these is to discover whether singing birds already detected by the daytime surveys are in song during the hours of midnight to 03:00, which would be indicative of unpaired individuals. Nocturnal visits will be welcome from any occupied tetrad. Nocturnal visits are not required from tetrads found to be empty from daytime surveys.
To reduce the chances of singing birds being missed by the tetrad surveys, we are keen for as many Nightingale records as possible from 2012 to be submitted to BTO, for example via the BirdTrack pages.
If you are able to offer any assistance, especially with nocturnal surveys, please contact your BTO Regional Representative as soon as possible.