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A metric for spatially explicit contributions to science-based species targets


The Convention on Biological Diversity’s post-2020 Global Biodiversity Framework will probably include a goal to stabilize and restore the status of species. Its delivery would be facilitated by making the actions required to halt and reverse species loss spatially explicit. Here, we develop a species threat abatement and restoration (STAR) metric that is scalable across species, threats and geographies. STAR quantifies the contributions that abating threats and restoring habitats in specific places offer towards reducing extinction risk. While every nation can contribute towards halting biodiversity loss, Indonesia, Colombia, Mexico, Madagascar and Brazil combined have stewardship over 31% of total STAR values for terrestrial amphibians, birds and mammals. Among actions, sustainable crop production and forestry dominate, contributing 41% of total STAR values for these taxonomic groups. Key Biodiversity Areas cover 9% of the terrestrial surface but capture 47% of STAR values. STAR could support governmental and non-state actors in quantifying their contributions to meeting science-based species targets within the framework.

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Fig. 1: Contribution to the global START score of different threats and the potential contribution of habitat restoration.
Fig. 2: Global distribution of START and STARR scores.
Fig. 3: STAR results for the Bukit Tigapuluh Sustainable Landscape and Livelihoods Project.

Data availability

Species’ extinction risk category, threat data, elevation limitations, habitat associations and distribution polygons are publicly available under specified terms and conditions of use from the IUCN Red List website6. Key Biodiversity Area boundaries are available from the World Database of Key Biodiversity Areas43, again under specified terms and conditions of use. The ESA CCI land use and cover maps are available at www.esa-landcover-cci.org39. Forest cover change maps are available from https://glad.umd.edu45. Digital elevation maps are available from https://earthexplorer.usgs.gov46. Global START and STARR scores for amphibians, birds and mammals at a grid cell resolution of 50 km are available in TIFF file format as Supplementary Data 1 and 2.


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We acknowledge funding from the Luc Hoffmann Institute, Vulcan, Synchronicity Earth and the Global Environment Facility, as well as support from the Conservation International GEF Project Agency. We thank L. Genasci (ADM Foundation) for providing technical guidance for the field tests, J. Deutsch for facilitating funding and R. Akçakaya for comments on the manuscript. L.M. is funded by Newcastle University and IUCN, L.P.K. by the National Research Foundation Singapore (NRF-RSS2019-007), M.B. by The Rufford Foundation and A.R. by the ‘Investissements d’Avenir’ programme, which is managed by the French National Research Agency (ANR-10-LABX-14-01).

Author information




L.M. led on analysis, development and manuscript drafting. L.A.B., T.M.B., S.H.M.B., F.H. and P.J.K.M. led on design and development and made substantial contributions to manuscript preparation. F.C.B., N.D.B., J.M.M.E., E.J.M.-G., M.H., K.M., N.B.W.M., D.C.R., A.S.L.R., X.S. and B.B.N.S. contributed substantially to conceptual development and manuscript preparation. C.R.B., C.G.-C., A.I., M.I., E.L., B.C.M., K.P. and M.F.T. contributed to conceptual development and data acquisition and analysis. E.L.B., C.B., G.C., A.C., M.E., G.A.B.d.F., R. Galt, A.G., L.G., R. Goedicke, J.M.H.G., R.D.G., S.L.L.H., D.G.H., J. Hughes, J. Hutton, M.P.W.K., L.M.N., E.N.L., A.J.P., P.P., H.P.P., A.R., E.C.R., C.R., J.D.S., J. Siikamäki, C.S., G.S., S.S., A.L.S., C.A.S.-N., S.N.S., H.J.T., A.V., F.V., L.R.V. and J.W. contributed to the conceptual development of the work. S.B., M.B., I.J.B., V.C., C.C., N.A.C., J.F., L.R.G., C.H.-T., R.J., A.J., L.N.J., L.P.K., T.E.L., P.F.L., B.L., D.M., M.P., B.A.P., C.M.P., M.C.R., N.S.R., J.P.R., J. Smart and B.E.Y. contributed to the acquisition of data. F.H. and P.J.K.M. contributed equally to conception and coordination.

Corresponding author

Correspondence to Louise Mair.

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Competing interests

E.C.R. works for Springer Nature, the publisher of Nature Ecology & Evolution. The other authors declare no competing interests.

Additional information

Peer review information Nature Ecology & Evolution thanks Julia Jones, Joseph Bennett and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Peer reviewer reports are available.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data

Extended Data Fig. 1 STAR threat-abatement scores for amphibians, birds and mammals per country shown as the percentage of the total global STAR threat-abatement score.

The total global STAR threat-abatement score represents the global threat abatement effort needed for all Near Threatened and threatened (Vulnerable, Endangered and Critically Endangered according to the IUCN Red List) amphibian, bird and mammal species to be reclassified as Least Concern. This score can be disaggregated spatially, based on the area of habitat currently available for each species in a particular location.

Extended Data Fig. 2 The percentage of the global STAR threat-abatement score for amphibians (green), birds (yellow) and mammals (blue), that is contributed by each threat type.

The total global STAR threat-abatement score can be calculated for each taxonomic group and then disaggregated by threat type, based on the known contribution of each threat to species’ risk of extinction.

Extended Data Fig. 3 STAR threat-abatement scores per country for (a) amphibians (b) birds and (c) mammals shown as the percentage of the total global STAR threat-abatement score for each taxon.

The total global STAR threat-abatement score for each taxonomic group can be disaggregated spatially, based on the area of habitat currently available for each species in a particular location.

Extended Data Fig. 4 Area of species’ current AOH and percentage of species current AOH per country.

(a) The distribution, and (b) the log10 distribution, of the area of species’ current AOH. (c) the percent of species’ current AOH per country (where species occurring across multiple countries have multiple datapoints) and (d) the largest percentage of current AOH per country for each species (such that there is only one datapoint per species). Colour scale indicates Red List category of species. Note the different y-axis in (b).

Extended Data Fig. 5 The number of Data Deficient species of amphibians, birds and mammals on the IUCN Red List per 50 km grid cell.

Of the 2,235 terrestrial species in these taxonomic groups that were assessed as Data Deficient on the Red List, 1,528 (68.4%) had Area of Habitat maps.

Extended Data Fig. 6 Deviation from ‘true’ STAR threat-abatement scores for birds generated by increasing the proportion of threat data with missing scope and severity scores.

Mean R2 per region across 100 iterations at the proportion of the data degraded (that is proportion of scope and severity data treated as missing) is increased. R2 from linear regression of STAR threat-abatement scores from degraded data against STAR threat-abatement scores from complete data. Each line is a region (N = 250) and regions are grouped based on the number of bird species present.

Extended Data Fig. 7 Variation in STAR threat-abatement scores for birds generated by (a-b) varying Red List category weights, and (c) weighting large AOH proportions more and small AOH proportions less.

The distribution of R2 values per region from regressing STAR threat-abatement scores obtained when species Red List categories were weighted using (a) log steps and (b) no weighting, against scores obtained using equal step weighting. (c) The distribution of R2 values per region from regressing STAR threat-abatement scores obtained when weighting larger AOH proportions per region more and smaller AOH proportions less.

Extended Data Fig. 8 Variation in STAR threat-abatement scores generated by varying the expected percentage population decline from scope and severity scores per threat.

R2 per region across 100 iterations (each box is a region) from regressing STAR threat-abatement scores obtained using varied expected population decline were against scores obtained using the median expected population decline. Regions are grouped by the number of bird species present. Boxplots show the median, with hinges indicating the first and third quartiles, whiskers showing the most extreme datapoint that is no more than 1.5 times the interquartile range from the respective quartile, and outliers beyond this distance shown as points.

Supplementary information

Supplementary Information

Supplementary Tables 1 and 2, Methods and Discussion.

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Supplementary Data 1

Global START scores for terrestrial amphibians, birds and mammals at a grid cell resolution of 50 km in TIFF file format.

Supplementary Data 2

Global STARR scores for terrestrial amphibians, birds and mammals at a grid cell resolution of 50 km in TIFF file format.

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Mair, L., Bennun, L.A., Brooks, T.M. et al. A metric for spatially explicit contributions to science-based species targets. Nat Ecol Evol (2021).

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