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Indicator facts

CBD Strategic Goal: B: Reduce the direct pressures on biodiversity and promote sustainable use

Main Aichi Biodiversity Target: Target 9: By 2020, invasive alien species and pathways are identified and prioritized, priority species are controlled or eradicated, and measures are in place to manage pathways to prevent their introduction and establishment.

Secondary Aichi Biodiversity Targets: Targets 5, 10, 11, 12, 17

CBD AHTEG Headline Indicators: Trends in pressures from habitat conversion, pollution, invasive species, climate change, overexploitation and underlying drivers; Trends in integration of biodiversity, ecosystem services and benefits sharing into planning, policy formulation and implementation and incentives

CBD Operational Indicators: Trends in number of invasive alien species; Trends in the impact of invasive alien species on extinction risk; Trends in policy responses, legislation and management plans to control and prevent spread of invasive alien species; Trends in the economic impacts of selected invasive alien species; Trends in incidence of wildlife diseases caused by invasive alien species; Trends in invasive alien species pathways management

Key Indicator Partners:


Associate Indicator Partners:

Development Status: Ready for global use


Background: Invasive alien species (IAS) are plants, animals or micro-organisms outside of their natural geographic range whose introduction and or spread threatens biodiversity, food security, human health, trade, transport and or economic development. They pose the second biggest threat to biodiversity globally, and in certain ecosystems, notably islands, the greatest threat to biodiversity. IAS have reached all corners of the globe and impact biodiversity in many ways. The cost of damage caused by invasive species is estimated as US$ 1.4 trillion per annum – close to 5% of global GDP.

Policy questions addressed by the indicator: Invasive species indicators and alien species trends allow assessment of the efficacy of biosecurity policies. Trends in policy responses, legislation and management plans to control and prevent spread of invasive alien species demonstrates the commitment of nations and institutions to addressing this threat.

Other questions (below) that the indicator will help answer are critical to decision making in management of this threat.

Pressure: Why are we losing biodiversity? What are the critical invasive species impact mechanisms and outcomes?

State: How is the status of biodiversity changing? Has there been an increasing trend in biological invasions?

Response: What do we do about biodiversity loss? Are pathways of introduction and spread being managed? Is there more awareness of the impacts of invasive species- are invasive species management strategies and action plans being developed?

Relationship to Aichi Target 9: The indicator relates directly to Aichi Target 9 and addresses in particular the species and management components of the target.

Data Information

Data available: Global time series (Global Trend (RLI: 1988-2008, international policy: 1950-2009, national policy: 1965-2009)); Regional/national time series (Europe time series 1900-2010, several European national time series); Global baseline (Number of documented IAS: 2009); Regional/national baseline (Comprehensive inventory for Europe: 2009, several other countries updated to 2013)

In addition, several regional or national case studies could be developed.

Global indicator aggregated from: National and regional level data, regional European data aggregated for trends

Indicator can be disaggregated at: Regional and national level, and by plants


A pressure-state-response model was used in which four indicators were developed and expressed for the purpose of assessing progress towards the 2010 Biodiversity Target for this threat to biodiversity:


1. Status of alien species invasion is expressed as the number of documented IAS per country.


2. Red List Index for impacts of invasive alien species shows the overall impact of IAS on the extinction risk of species globally. It is a measure of how fast IAS are driving the world’s biodiversity to extinction (and how effectively we are mitigating this).


3. Trends in international invasive alien species policy shows the number of international agreements relevant to controlling IAS and how this has changed through time, as well as the change in the number of countries party to these agreements.

4. Trend in national invasive alien species policy shows the percentage of countries with national legislation relevant to IAS concerns and how this has changed through time as countries acknowledge the IAS problem and commit to responding to this threat.

Last update: 2010

Next update: 2014 (funding dependent)


Level at which the indicator is currently used: Global

Level at which indicator could also be used: Regional, national

Three of the indicators are measured at a country scale and aggregated up to global scale. As a result they can be disaggregated to examine the status of invasion and trends in international and national policy at regional and national scales. The Red List Index is expressed globally, but may be applied nationally.

Indicator presentation

PRESSURE: Example of IAS impact for birds

STATE: Cumulative percentage of bird species undergoing genuine IUCN Red List category changes driven by impacts of IAS

RESPONSE: Adoption of national legislation relevant to the prevention or control of IAS

Source: Global indicators of biological invasion: species numbers, biodiversity impact and policy responses, McGeoch et al., Diversity and Distributions 16, Copyright © , Blackwell Publishing Ltd


How to Interpret the Indicator

PRESSURE: The greater the number of documented IAS the greater the threat to biodiversity from IAS. The number of AS is the best proxy of number of IAS, and can be used to assess trends of invasions (See Genovesi et al 2013 for an explanation)

STATE: The greater the decline in the Red List Index driven by IAS, the greater the impact on biodiversity from IAS.

RESPONSE: The more countries with IAS legislation, the greater the global commitment to controlling the threat to biodiversity from IAS. The larger the number of IAS-relevant international policies, and the greater the level of national commitment to these, the greater the global commitment to controlling IAS. The more international agreements a country is party to the more strongly committed the country is to controlling IAS.


Current Storyline
PRESSURE: The number of IAS is higher on islands and in countries that are more developed and have more information available on IAS. The mean number of IAS per country is 50 for the 57 countries assessed.
STATE: Red List Indices show that the extinction risk of birds, mammals and amphibians is increasing over time. Analyses of the drivers of these shifts in species status show that for all three groups, IAS were having a net negative impact. Although some threatened species have improved in status (as a result of successful control or eradication of IAS), more have been uplisted to higher threat categories owing to increasing spread and threats from IAS.
RESPONSE: There are 10 international agreements with provisions for tackling IAS that have been ratified by a cumulative total of 1,434 signatories (82% of the maximum possible number). All countries are signatory to at least two IAS-relevant international conventions; more than 90% are signatory to at least half, and 8% of countries are signatory to all 10. 55% of countries have overarching national legislation to manage, control and/or limit the spread and impact of IAS.
National Use

Data for three of the indicators is collated at a national level. However national level assessments by countries would serve to validate these data. For development of an indicator regarding the implementation of management plans for invasive alien species, information is required at a national level which can then feed into a global indicator. The expression of the Red List index for IAS at a national level requires national red list assessments of threatened species and the factors which threaten them. More information about producing national RLIs can be found in the publication, IUCN Red List Index – Guidance for National and Regional Use, available from the 2010 BIP webpage for this indicator.

At a regional scale indicators have been produced for Europe through the Streamlining European 2010 Biodiversity Indicators project (

A website for the indicator is in the process of being constructed.


For more information about national invasive alien species indicators email Shyama Pagad, Programme Officer of IUCN SSC Invasive Species Specialist Group.

Future development

In the case of the operational indicator 'Trends in number of invasive alien species' future development planned includes increasing the number of countries and taxa for the invasion pressure indicator (and expression of trends therein). Annotated inventories of invasive alien species, across taxa for at least 120 countries, will be validated by the end of 2013 with plans to include all CBD parties by mid-2014. This will include an update of information for the 52 countries that were measured for this indicator in 2010

Updates of the operational indicators 'Trends in the impact of invasive alien species on extinction risk trends' and 'Trends in policy responses, legislation and management plans to control and prevent spread of invasive alien species'  are planned.

 Information on policy responses, legislation and management plans to control and prevent spread of invasive alien species for the Pacific region (22 Pacific Island Countries and Territories) will be compiled and available by the end of 2013

Response indicators that directly reflect on-the-ground action against IAS (management effectiveness) are being planned (e.g. control of pathways, operational management plans, numbers of vertebrate eradications, and extent of invasion). A scoping study for the development of an indicator on invasive alien species vertebrate eradications is underway with key partners.

Two other operational indicators 'Trends in the economic impacts of selected invasive alien species' & 'Trends in incidence of wildlife diseases caused by invasive alien species' are being considered for development.


Indicator Publications
Monitoring Trends in Biological Invasion, its Impact and Policy Responses (2013)Genovesi, P., Butchart, S. H. M., McGeoch, M. A., and Roy, D. B. In: Biodiversity Monitoring and Conservation: Bridging the Gap Between Global Commitment and Local Action. Collen, B., Pettorelli, N., Baillie, J. E. M., Durant, S. M., Eds. Willey-Blackwe
Invasive alien species indicators in Europe. A review of streamlining European biodiversity (SEBI) Indicator 10 (2012)Rabitsch, W., Essl, F., Genovesi, P. & Scalera, R. EEA, Copenhagen: 44 pp
Uncertainty in invasive alien species listing (2012)McGeoch et al. Ecological Applications, 22, 959-971
Global indicators of alien species invasion: threats, biodiversity impact and responses. (2010)McGeoch, M.A., Butchart, S.H.M., Spear, D., Marais, E., Kleynhans, E.J., Symes, A., Chanson, J. and Hoffmann, M. Diversity and Distributions 16, 95-108.
GISP Expert Working Group Meeting on Development of Indicators for Invasive Alien Species (GISP Expert Working Group 2008)Summary Minutes
Development of an Invasive Species Indicator for assessing progress towards the 2010 Biodiversity Target (GISP 2008)Background document
Measuring trends in invasive alien species: an achievement of fifty years of invasion politics? (GISP 2008)Poster presentation
Status of alien species invasion and trends in invasive species policy (2008)Proof of Concept report for the Global Invasive Species Programme. Centre for Invasion Biology, Stellenbosch.
Red List Indices to measure the sustainability of species use and impacts of invasive alien species (2008)Journal Article: Butchart, S.H.M. Bird Conservation International 18, S245-S262.
Ad hoc meeting of invasive alien species data provider and user groups to develop the 2010 indicator (2007)Report: Biodiversity Indicators Sub-Committee, IUCN SSC & NERC Centre for Population Biology.
A global indicator for biological invasion (2006)Journal Article: Multiple authors. Conservation Biology 20, 1635-1646.
Options for a global indicator on trends in invasive alien species (2006) Report to the Secretariat of the Convention on Biological Diversity (SCBD). Mulitple authors.
Using Red List Indices to measure progress towards the 2010 target and beyond (2005) Journal Article: Mulitiple authors. Philosophical Transactions of the Royal Society B 360, 255-268.
Indicator links

Invasive Alien Species Indicator website: under development

Invasive Alien Species Indicator Outcomes

Photo credits:
Water Hyacinth ©sarahemcc; Vespula vulgaris ©Nigel Jones; Tamarix ramosissima ©KingsBrae Garden

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