How many bird and mammal extinctions has recent conservation action prevented?

We hear much about the worsening status of species, and in particular, that increasing numbers of species face extinction. Indeed, the landmark Global Assessment from the Intergovernmental Platform on Biodiversity and Ecosystem Services reported that 1 million species may be at risk of extinction.
Published in Ecology & Evolution

The same report concluded that global targets set by the UN’s Convention on Biological Diversity were likely to be missed, and that the target for conserving species, known as Aichi Biodiversity Target 12, was faring particularly badly. Despite all this bad news, we knew that there were conservation successes and that the status of species would be even worse without conservation efforts for species on the brink of extinction.

At a dinner in early 2019 during a workshop to kick-start another collaboration, a small group of authors (Rike Bolam, Tom Brooks, Stu Butchart, Mike Hoffmann, Louise Mair, Philip McGowan, Ana Rodrigues) discussed what it would take to carry out a robust assessment of how many birds and mammals had avoided extinction because of conservation action. An assessment in 2006 led by Butchart quantified the number of birds that would have gone extinct without such action since 1994. We wanted to update this work, develop more robust methods and encompass mammals as well as birds, in order to determine how far Aichi Target 12 had stimulated similar successes during 2010-2020. Discussions with the Secretariat of the Convention on Biological Diversity indicated that they were also interested in determining the degree to which conservation efforts had prevented extinctions since the Convention had come into force in 1993.

We agreed that this would require identifying a shortlist of species, based on robust criteria, and then running an expert elicitation process to estimate probabilities that conservation actions had prevented extinction for each candidate species. We could not simply filter information available on the IUCN Red List to produce a shortlist of species. Instead, we identified a larger group of 631 potential candidates using information on the Red List that we then investigated in detail and whittled down to a shortlist of 73 species. The next step involved standardising information that we would use for making our assessments, and getting this checked by experts on each individual species. At this stage, we contacted over 270 taxon experts. This in itself was a huge task and required some careful planning and meticulous recording of contributions.

Their additional input allowed us to reduce the list to 61 candidate species that would be the focus of our efforts to evaluate data on their trajectory towards extinction and the impact of conservation actions in preventing this outcome.

We recruited a diverse set of 66 experts in species conservation, each of whom evaluated the probability that each of the 39 bird and/or 22 mammal species would have gone extinct without conservation action. The experts made their estimates individually, discussed the anonymised results collectively, then reviewed and revised their estimates, again anonymously. We convened the groups through some marathon zoom calls lasting up to 7 hours, further complicated by the fact that our experts were located in different time zones, from Colombia to Australia. We all therefore had experience of spending a whole day (or night) on Zoom before the pandemic hit!

We used medians of these final estimates for further analysis. As well as publishing the results in a paper in Conservation Letters, we presented them to CBD’s technical body and fed them into the Global Biodiversity Outlook 5 – the final verdict on the degree to which each of the Aichi Targets was met. Our finding that up to 25 bird and mammal species would probably have been driven extinct without conservation action since 2010 (and up to 48 since 1993) provided a welcome positive note in the otherwise bleak findings in this report.

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Life Sciences > Biological Sciences > Ecology