| Title | Biodiversity: Index of abundance of terrestrial breeding birds. |
Associated Targets | Biodiversity: increase the index of abundance of terrestrial breeding birds |
Brief Description | The indicator describes changes in the numbers of breeding birds in Scotland. Birds can respond relatively quickly to variations in habitat quality, through changes in breeding output, survival or dispersal. Since most bird species are relatively easy to identify and count, geographically widespread, abundant and diurnal, birds are often used as indicators of environmental change. |
Strategic Objective(s) to Which Indicator Relates | The indicator informs progress towards a Greener Scotland by capturing improvements in biodiversity in the wider countryside, as measured by an index of terrestrial breeding birds. All public bodies have a statutory duty to further biodiversity conservation and so improvements in the index will involve working in partnership with delivery bodies. |
More Detailed Definitions | |
Definitions of Keywords | Index of abundance is an index which combines information on the numbers of selected species, rather than their spatial coverage. Terrestrial breeding birds in Scotland comprise of resident and migratory species. They include familiar species of the garden such as blackbird Turdus merula and robin Erithacus rubecula, woodland such as willow warbler Phylloscopus trochilus and goldcrest Regulus regulus, farmland species such as linnet Carduelis cannabina and goldfinch Carduelis carduelis, and uplands such as raven Corvus corax and black grouse Tetrao tetrix. |
Evidence Source | Terrestrial breeding birds are recorded primarily through the Breeding Bird Survey ( BBS). Since 1994 the BBS has recorded population estimates of birds in Scotland based on a random sample of 1km Ordnance Survey grid squares which are representative of the main terrestrial habitats. Two visits are made to each 1km square, in spring and early summer. Ten species are included in the indicator which are too scarce to be monitored by the BBS but are surveyed in other ways. As noted in the brief description, birds are a good indicator of environmental change. The indicator is a proxy measure of biodiversity, as biodiversity cannot be measured by a single indicator. |
Baseline and Past Trends | The baseline is 2006. In 2006, the mean index of abundance for the 68 terrestrial breeding bird species was 110. This data was published by SNH in August 2008. A times series including the most up to date data is available on Scotland Performs. http://www.scotland.gov.uk/About/scotPerforms/indicators/breedingBirds |
Methodology for Data Source | The methodology for constructing the index is to determine the species for which there is suitable data available (in this case species which are present in 30 or more 1km squares) then a mean index of change is calculated based on all of the species. The methods are described fully in Commissioned Research Report 245. |
Data Ownership and Quality Assurance | Data is supplied by British Trust for Ornithology and Royal Society for Protection of Birds to Scottish Natural Heritage under contract. NS status is under consideration. |
Publication of Data | The Terrestrial Birds index is published by SNH, future updates are planned to be available annually every March (data is 15 months in arrears) . The data will be available on the SNHi website. Scottish Natural Heritage have also published a detailed technical report Commissioned Research Report 245. The indicator is scheduled for a complete re-analysis every five years so as to ensure that we are using the best methods and/or data sources possible. |
Methodology for Recent Change Arrow on Scotland Future issues or reviews | This evaluation is based on: any difference in the index within +/- 3 points of last year's figure suggests that the position is more likely to be maintaining than showing any change. An increase of 3 index points or more suggests the position is improving; whereas a decrease of 3 index points or more suggests the position is worsening. This methodology is currently under review. SNH have commissioned research to provide an estimate of the uncertainty of year on year changes. The results from this work will be used to revise the methodology for determining the change arrow. |