D6: Relative abundance and distribution of priority species in England

Interim Interim

Short description

Priority Species are those identified as the most threatened or declining species in the UK. They were identified to support UK conservation planning and are published and maintained by the Joint Nature Conservation Committee. Priority species are used as the reference source to produce statutory species lists of principal conservation importance. Such lists are published by the Secretary of State under Section 41 of the Natural Environment and Rural Communities Act 2006. There are over 940 priority species recognised in England.

This indicator has 2 components: (a) changes in the relative abundance of those priority species for which suitable abundance data are available; and, (b) changes in distribution (the number of 1 km grid squares in which species are recorded in any given year) of those priority species for which distribution data are available.

The taxonomic coverage of this indicator is limited at present. The relative abundance measure includes priority birds, butterflies, some mammals (one hare and 5 bats) and moths but does not currently include plants, fungi, amphibians, reptiles, fish or invertebrates other than butterflies and moths; the distribution measure includes priority species of bryophytes, lichens, insects and other invertebrates but does not currently include amphibians, reptiles, birds, fish or mammals.

This indicator is not available for reporting in 2021 in a finalised form. Trends for the relative abundance and distribution of priority species at a UK-level are already presented annually in the UK Biodiversity Indicators; however, further work has been undertaken to develop equivalent measures at an England-only level. The results of this work are presented here for the first time in 2021 as a revised interim indicator. Information on how these data have been obtained and how the statistics have been calculated is available on the Defra science portal. The report includes a technical background document that describes the data sources and methods in detail, and spreadsheets that contain a list of species within each index together with the data behind the indices. Methods are being developed to refine the future reporting of this indicator and to expand the taxonomic coverage. These methods are still undergoing peer review and user feedback is invited via 25YEPindicators@defra.gov.uk.

Note

Of the more than 940 species in the priority species list for England, 149 have robust quantitative time-series data on relative abundance and 181 have suitable distribution data. The relative abundance measure comprises Birds (44), Butterflies (21), Mammals (6) and Moths (78); the distribution measure includes Bees (13), Bryophytes (9), Lichens (16), Moths (93), Spiders, (9) and Wasps (7). Approximately 60 species of moths appear in both the relative abundance and distribution measures; the remaining species within this indicator are unique to one or other of the measures because they are drawn from different data sources. The abundance datasets are generated largely from data collected by national monitoring schemes, whereas the distribution data are collated through the Biological Records Centre and include contributions from a wide range of national recording schemes (see the technical background document referenced in the ‘Readiness and links to data’ section for further detail).

Trend description

a) Changes in abundance of priority species

By 2018, the index of relative abundance of priority species in England had declined to 17.7% of its base-line value in 1970, a statistically significant decrease. Over this long-term period, 7% of species showed a strong or weak increase and 83% showed a strong or weak decline. More recently, between 2013 and 2018, the relative abundance index declined from 21.3 to 17.7 (17% of the 2013 value), again a statistically significant decrease. Over this short-term period, 20% of species showed a strong or weak increase and 56% showed a strong or weak decline.

b) Changes in distribution of priority species

By 2016, the index of distribution of priority species in England decreased to 84, a statistically significant decrease of 16% of the 1970 value. Over this long-term period, 24% of species showed a strong or weak increase and 38% showed a strong or weak decline. More recently, between 2011 and 2016, the distribution index declined from 92.3 to 83.7 (9% of the 2011 value), again a statistically significant decrease. Over this short-term period, 13% of species showed a strong or weak increase and 59% showed a strong or weak decline.

Sub-categories

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This table provides metadata for the interim or final indicator presented above.

Indicator name

Relative abundance and distribution of priority species in England

Indicator reference

D6

Outcome Indicator Framework theme

Wildlife

Headline indicator status

Not applicable

Relevant goal(s) in the 25 Year Environment Plan
  • Thriving plants and wildlife
Relevant target(s) in the 25 Year Environment Plan
  • Taking action to recover threatened, iconic or economically important species of animals, plants and fungi, and where possible to prevent human induced extinction or loss of known threatened species in England and the Overseas Territories
Position in the natural capital framework
  • Condition of assets - species and ecological communities
Related reporting commitments
  • Relevant to Convention on Biological Diversity
  • Sustainable Development Goal 15 Life on Land
Geographic scope

England

Status of indicator development

Interim

Date last updated

11 June 2021