durrellindex

#10 The Red List Index of species survival: What is the long-term impact of Durrell’s conservation programmes on its target species’ chances of survival?

The Red List Index (RLI) measures the impact of Durrell’s conservation work. It compares the way the overall extinction risk of 17 of its target mammal, bird and amphibian species has changed to a theoretical scenario in which conservation has not taken place.

The RLI measures changes in the chances of survival of each species by tracking its movement over time through IUCN Red List categories of extinction risk. These categories are assigned by independent experts who follow the rigorous and authoritative IUCN Red List assessment process.

Eight of Durrell’s target species have moved into lower Red List categories since 1988 – six Mauritian birds, the Golden Lion Tamarin and the Mallorcan Midwife Toad – meaning their numbers have significantly increased and therefore their risk of extinction decreased.

This has driven a striking upward trend in the RLI, demonstrating that Durrell’s programmes are moving many species away from extinction. Without conservation efforts, some of these species would almost certainly have gone extinct in the wild, and overall our species would have been in far worse shape than they are today.

A 2010 scientific paper in a world-leading journal showed that, at a global level since the 1980s, 63 mammal, bird and amphibian species have moved down the Red List because of conservation. That means Durrell and its partners have led or contributed to more than 10% of these globally significant improvements in the status of species.

Red

Lis

t Ind

ex o

f Sp

ecie

s Su

rviv

al

Time

Towardssafety

Towardsextinction

0.1

0.6

1988

1992

1996

2000

2004

2008

2012

-23% without conservation

+44% with conservation

Durrell’s impact innumbers