C4. Status of UK priority species

C4a. Status of priority species – relative abundance

 

Type: State Indicator

 

Summary

Figure C4ai.  Changes in the relative abundance of priority species in the UK, 1970 to 2012.

Figure C4ai. Change in the relative abundance of priority species in the UK, 1970 to 2012

Notes:

  1. Based on 213 species.  Dotted lines show the 95 per cent confidence intervals relative to the 1970 reference year.
  2. Bar chart shows the percentage of species increasing or declining over the long-term (1970 to 2012) and the short-term (2007 to 2012).
  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) and Section 42 (Wales), 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

Relative abundance of priority species

indicator declining
1970–2012

2010 indicator stable
2007–2012

Decreased (2012)

 

 

  • Official lists of priority species have been published for each UK country and actions to conserve these priority species are included within the respective country biodiversity or environment strategies.  The species included in the indicator are those on one or more of these priority species lists, for which population abundance data are available.
  • By 2012, populations of priority species overall had declined to 33 per cent of the 1970 index value, a statistically significant decrease.  Over this long-term period 25 per cent of species showed an increase and 75 per cent showed a decline.
  • Between 2007 and 2012, populations of priority species declined by 4 per cent relative to their value in 2007.  This decrease is not statistically significant.  Within the index over this short term period, 47 per cent of species showed an increase and 53 per cent showed a decline.
  • The measure is a composite indicator of trends in 213 species from the following taxonomic groups: birds; butterflies; mammals; and moths.  They 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. 

 

Indicator description

The indicator shows relative population changes of priority species in the UK for which population abundance 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) and Section 42 (Wales), Northern Ireland Priority Species List, Scottish Biodiversity List).  The combined list contains 2,890 species in total.

Of these 2,890 species, the 213 for which robust quantitative time series of relative species abundance are available are included in the indicator.  These 213 species include birds (101), butterflies (21), mammals (12) and moths (79).  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 index declined from 100 to 33 between 1970 and 2012.  The long-term change between 1970 and 2012 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 per cent confidence intervals between first and last date of the long and short term changes respectively.  To calculate the short-term trend, a change statistic for the 2007 to 2012 period was calculated and the data re-sampled to provide confidence intervals on that change statistic (not shown in Figure C4ai).  In 2012 the relative abundance of the 213 species included in the indicator had declined by four per cent relative to their 2007 levels; this decline was not statistically significant and the indicator is considered to have remained stable.

The priority species identified in each of the four UK countries were highlighted as being of conservation concern for a variety of reasons, including rapid decline in some of their populations.  The short-term assessment of change is the key way of assessing progress towards halting and reversing the long-term declines of these species. 

 

Relevance

Priorities for species and habitat conservation are set at a country level through country biodiversity or environment strategies.  Each country has an identified list of priority species, which are of high conservation concern due, for example, to restricted range or population declines.

 

Background

The time series for each species in the indicator is scaled as a percentage of its value in its first year.  Each species is given equal weighting, and the annual index value is the geometric mean of the scaled species values for that year.  For species trends entering the indicator after the first year, their value in the first year is set to the geometric mean of those species trends already in the indicator.  Any missing values are estimated using linear interpolation (Collen et al. 2008) and one per cent of the trend average is added to any trends containing zero values (Loh et al. 2005).  Species trends ending prior to the end year of the indicator are held at their final values to the end of the data series (currently 2012).  Data from 2013 are available for some species, but as they are not available for many species the indicator has been calculated to 2012 only, although data from 2013 may have influenced 2012 species index values.

The overall trend shows the balance across all the species included in the indicator.  Populations of individual species within each measure may be increasing or decreasing in abundance (Figure C4ai).  Estimates will be revised when new data or improved methodologies are developed and will, if necessary, be applied retrospectively to earlier years.  Further details about the species that are included in the indicator, and the methods used to create the priority species indicator can be found in the technical background paper.

Confidence intervals for each year are created using bootstrapping (Buckland 2005; Freeman et al. 2001).  In each iteration a random sample of species is selected and the geometric mean calculated.  The headline indicator (Figure C4ai) masks variation between the taxonomic groups.  Figure C4aii shows an index for each taxonomic group separately, generated using the same methods as the headline indicator.

 

Figure C4aii.  Change in relative species abundance by taxonomic group, 1970 to 2012.

Figure C4aii. Change in relative species abundance by taxonomic group, 1970 to 2012

Notes:

  1. Figures in brackets show the number of species included in each measure.
  2. Graph shows unsmoothed trend (solid line) with its 95 per cent 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.

 

Further development planned

The indicator of relative abundance will be refined in future as further data become available. The basis of assessment, particularly for the short-term change, may also be refined, for example, by investigating statistical smoothing to detect underlying trends and reduce the impact of particularly high or low values at the start or end of a time series.

It is anticipated that the general approach of the indicator developed for reporting in 2014 will be retained into the future, however, it is likely that the work will be refined and expanded. 

Regardless of advances in statistical techniques, there are likely to be species on the priority species lists for which little monitoring or occurrence data is available.  This is for a variety of reasons, including rarity, difficulty of detection, or those for which monitoring methods are unreliable or unavailable.  In order for the indicator to be representative of priority species, a method of assessing the changing status of these remaining data poor species will need to be considered.

 

Goals and targets

Aichi Targets for which this is a primary indicator

Strategic Goal C. To improve the status of biodiversity by safeguarding ecosystems, species and genetic diversity.

Aichi icon 12Target 12: By 2020, the extinction of known threatened species has been prevented and their conservation status, particularly of those most in decline, has been improved and sustained.

 

Aichi Targets for which this is a primary indicator

None

 

Web links for further information

Reference

Title

Website

Bat Conservation Trust 

The National Bat Monitoring Programme

http://www.bats.org.uk/pages/nbmp.html

British Trust for Ornithology

Indicators of wild bird populations

http://www.bto.org/science/monitoring/
developing-bird-indicators

Butterfly Conservation

Butterflies and Moths

http://butterfly-conservation.org/44/butterflies-
and-moths.html

UK Butterfly Monitoring Scheme

Butterflies as indicators

http://www.ukbms.org/indicators.aspx

Joint Nature Conservation Committee   

Seabird Monitoring Programme

http://jncc.defra.gov.uk/page-1550

People’s Trust for Endangered Species

National Dormouse Monitoring Programme

http://www.ptes.org/?page=186

UK Biodiversity Partnership

UK Biodiversity Action Plans 

http://jncc.defra.gov.uk/ukbap

Wildfowl and Wetlands Trust

National water bird estimates

http://www.wwt.org.uk/research/monitoring/

Scottish Natural Heritage

Scottish Biodiversity List

http://www.scotland.gov.uk/Topics/Environment/
Wildlife-Habitats/16118/Biodiversitylist/SBL

Natural Resources Wales

S42 List of priority species in Wales

http://www.biodiversitywales.org.uk/en-GB/
Section-42-Lists

Natural England

S41 List of priority species in England

http://webarchive.nationalarchives.gov.uk/
20140605090108/http:/www.naturalengland.org.uk/
ourwork/conservation/biodiversity/protectandmanage/
habsandspeciesimportance.aspx

Northern Ireland Environment Agency

Northern Ireland Priority Species List

http://www.habitas.org.uk/priority/intro.html

 

References

Buckland, S.T., Magurran, A.E., Green, R.E. & Fewster, R.M. (2005) Monitoring change in biodiversity through composite indices. Philosophical Transactions of the Royal Society of London. Series B, 360, 243–254.

Collen, B., Loh, J., Whitmee, S., McRae, L., Amin, R. & Baillie, J. (2008) Monitoring Change in Vertebrate Abundance: the Living Planet Index. Conservation Biology, 23, 317-327.

Freeman, S.N., Baillie, S.R. & Gregory, R.D. (2001) Statistical analysis of an indicator of population trends in farmland birds, BTO Research Report no. 251, Thetford.  http://www.bto.org/sites/default/files/u196/downloads/rr251.pdf (PDF, 285kb)

Loh, J., Green, R. E., Ricketts, T., Lamoreux, J., Jenkins, M., Kapos, V. & Randers, J. (2005) The Living Planet Index: using species population time series to track trends in biodiversity. Philisophical Transactions of the Royal Society. Series B, 360, 289–295.

 

Download Datasheet

Download Technical background paper
 

Last updated: December 2014

Latest data: 2012