Corncrake national surveys - raw data

Quality Control

RSPB fieldworkers follow the standard methodology and collect the majority of the dataset. Some records do not have a date; in this case the whole survey period (between 1st April and 31st August) is quoted. For records without a clear location at 100m precision, the 1km square is given. These data have been mapped and checked for sensitivities and typographical/geographical errors

Method steps

1. Surveys are conducted at night. Two visits are made between 20th May and 10th July between 00.00 and 03.00 hours BST. Estimated locations of singing males are recorded in all areas known to have suitable habitat. All verified records of nests and chicks are included. Information about daytime singing locations and records outside the census period are included only if no night-time survey work can be undertaken, for example if the area is too remote. In order to verify records and validate the dataset, the data have been mapped and thoroughly checked. Geographical checks have included comparing the distribution with that shown in the published paper and ensuring that records with the same area name are located close to each other.

Two types of survey are undertaken. In National surveys the whole corncrake population of Britain and the Isle of Man is surveyed. In Core Area surveys, counts are undertaken on the Hebridean islands and Orkney. These islands represent the core range of the corncrake in Britain and hold more than 90% of the breeding population.