C4. Status of UK priority species

C4a. Relative abundance

 

Type: State Indicator

 

Indicator Description

The indicator shows changes in relative abundance of priority species in the UK for which data are available.  Priority species are defined as those on one or more of the biodiversity lists of each UK country (Natural Environmental and Rural Communities Act 2006 - Section 41 (England), Environment (Wales) Act 2016 section 7, Northern Ireland Priority Species List, Scottish Biodiversity List).  The combined list contains 2,890 species in total.  The priority species were highlighted as being of conservation concern for a variety of reasons, including rapid decline in some of their populations.  This indicator should be read in conjunction with C4b which provides data on those species for which distribution information is available.

Summary

 

Official lists of priority species have been published for each UK country; actions to conserve these priority species are included within the respective country biodiversity or environment strategies.

By 2015, the index of relative abundance of priority species overall had declined to 32% of the 1970 index value, a statistically significant decrease.  Over this long-term period 27% of species showed an increase and 73% showed a decline.

Between 2010 and 2015, the index declined by 18% relative to the value in 2010, a statistically significant decrease.  Within the index over this short-term period, 42% of species showed an increase and 58% showed a decline.

 

Figure C4ai.  Change in the relative abundance of priority species in the UK, 1970 to 2015.

Figure C4ai. Change in the relative abundance of priority species in the UK, 1970 to 2015.

Notes:

  1. Based on 215 species.  The line graph shows the unsmoothed trend (dotted line) with its 95% confidence interval (shaded). 
  2. he bar chart shows the percentage of species increasing or declining over the long-term (1970 to 2015) and the short-term (2010 to 2015).
  3. All species in the indicator are present on one or more of the country priority species lists (Natural Environmental and Rural Communities Act 2006 – Section 41 (England), Environment (Wales) Act 2016 section 7, Northern Ireland Priority Species List, Scottish Biodiversity List).

Source: Bat Conservation Trust, British Trust for Ornithology, Butterfly Conservation, Centre for Ecology & Hydrology, Defra, Joint Nature Conservation Committee, People’s Trust for Endangered Species, Rothamsted Research, Royal Society for the Protection of Birds.  

 

Assessment of change in the relative abundance of priority species in the UK

 

Long term

Short term

Latest year

Priority species Relative abundance

indicator declining
1970–2015

indicator declining
2010-2015

No change (2015)

 

Of these 2,890 species in the combined priority species list, the 215 for which robust quantitative time series of relative species abundance are available are included in the indicator.  These 215 species include birds (103), butterflies (21), mammals (11) and moths (80).  This selection is taxonomically limited at present; it includes no vascular or non-vascular plants, fungi, amphibians, reptiles, or fish.  The only invertebrates included are butterflies and moths.  The species have not been selected as a representative sample of priority species and they cover only a limited range of taxonomic groups.  The measure is therefore not fully representative of species in the wider countryside.  The time series that have been combined cover different time periods, were collected using different methods and were analysed using different statistical techniques.  In some cases data have come from non-random survey samples.  See the technical background document for more detail. 

The index declined from 100 to 32 between 1970 and 2015.  The long-term change between 1970 and 2015 is therefore assessed as a decrease.  This assessment was made on the unsmoothed time series of relative species abundance generated by the data providers.  The assessment is based on a test of statistical significance that compares the change and 95% confidence intervals between 1970 and 2015.  To calculate the short-term trend, a change statistic between 2010 and 2015 was calculated for each species, these short-term trend estimates were then re-sampled to provide confidence intervals on that change statistic (Eaton et al. 2015).  In 2015, the index of relative abundance of the 215 species included in the indicator had declined by 18% relative to the 2010 level; a statistically significant decline.

 

Figure C4aii.  Change in relative species abundance by taxonomic group, 1970 to 2015.

 

Figure C4aii. Change in relative species abundance by taxonomic group, 1970 to 2015.

 

Notes:

1.     Figures in brackets show the number of species included in each measure.

2.     Graph shows unsmoothed trend (dotted line) with its 95% confidence interval (shaded).

Source: Bat Conservation Trust, British Trust for Ornithology, Butterfly Conservation, Centre for Ecology & Hydrology, Defra, Joint Nature Conservation Committee, People’s Trust for Endangered Species, Rothamsted Research, Royal Society for the Protection of Birds.

 

Download Fiche

Download Datasheet

Download Technical background document

Download Evidence statement


 

Last updated: August 2017

Latest data: 2015