Cetti's warbler national survey in the UK and the Channel Islands in 1996

Quality Control

These data have been gathered by trained field-workers and the data are of high quality. The data have been mapped and checked for sensitivities and typographical/geographical errors.

Method steps

1. A comprehensive list of all known sites where breeding Cetti’s warblers were recorded at any time over the previous 10 years (1986-1995) was compiled from records of the Rare Breeding Birds Panel (RBBP) and county bird reports and by communication with county bird recorders. The information for each site included, where possible, the years that Cetti’s Warblers were recorded and its 6-figure grid reference (to ensure no duplication of records known by more than one site name).
   
   The 1996 survey was based on visits to these sites. Historical sites (sites with records pre 1986) were only surveyed if there were records from more than one year.
   
   The aim of the survey was to record all male Cetti’s warbler territories on each site by recorded singing males during these three separate visits. Each visit took place between dawn and 1000hrs on a dry day with little wind. Dates for each visit were as follows, visit 1: 23rd March : 14th April, visit 2: 15th April : 12th May and 13th May : 2nd June.
   
   Observers recorded the number of singing males on each visit and estimated the total number of territories on the site. Observers were given the option to record minimum and maximum numbers of territories owing to potential problems with differentiating between singing males in the field. 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.

This survey was restricted to counties with previous records of Cetti’s warbler in addition to survey of tetrads along the Rivers Frome, Piddle and Stour in Dorset and Avon, Itchen and Test in Hampshire encompassing all known Cettis records.

Jersey was also covered as part of this survey. These records will be provided when mapping for the Channel Islands becomes available on the NBN. All data were uploaded at a 100m resolution.