Common scoter national breeding surveys in Britain

Quality Control

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

Method steps

1. Three visits were made to all known breeding sites and a sample of potential breeding sites. The surveys were carried out between March and June and were timed to coincide with the common scoter's arrival in Britain, prior to breeding, when birds spend most of the day in open water. During the 1995 survey, three visits were made to all known and a sample of potential breeding sites. The 2007 survey followed the same approach and each site was visited three times (once within each two-week period of the six-weeks of the survey) and was based on a three-stratum design. Stratum one included lochs for which there have been records of breeding or potentially breeding scoter during the 1995 survey or since. Stratum two consisted of lochs, at which breeding had been recorded historically, but not during the 1995 survey nor since. Stratum three were lochs that were randomly selected from all lochs within 20 km of a stratum one site (as long as the lochs met certain criteria). In addition, there are also some records, which have been allocated to stratum four (sites for which information was available from RSPB Forsinard reserve, and would effectively fall into either stratum 1 or 2). Some records do not have a stratum and this is because they were sites that were visited supplementary to the survey design either by surveyors from the Wildfowl and Wetlands Trust or by other surveyors.

The national common scoter surveys covered the following areas: Shetland, Flow Country, West and South Scotland and Islay. Record precision is the area of the loch. Grid references indicate a location on or near the lochs where the species was recorded, and may not indicate the exact location where the species was seen.