The dynamics underlying avian extinction trajectories forecast a wave of extinctions

Abstract

Population decline is a process, yet estimates of current extinction rates often consider just the final step of that process by counting numbers of species lost in historical times. This neglects the increased extinction risk that affects a large proportion of species, and consequently underestimates the effective extinction rate. Here, we model observed trajectories through IUCN Red List extinction risk categories for all bird species globally over 28 years, and estimate an overall effective extinction rate of 2.17 × 10 −4 /species/year. This is six times higher than the rate of outright extinction since 1500, as a consequence of the large number of species whose status is deteriorating. We very conservatively estimate that global conservation efforts have reduced the effective extinction rate by 40%, but mostly through preventing critically endangered species from going extinct rather than by preventing species at low risk from moving into higher-risk categories. Our findings suggest that extinction risk in birds is accumulating much more than previously appreciated, but would be even greater without conservation efforts.

Conservation in the maelstrom of Covid‐19 – a call to action to solve the challenges, exploit opportunities and prepare for the next pandemic

“…Conservation action works. In many cases, we already know how to reduce species’ extinction rates (Hoffmann et al ., 2010; Monroe et al ., 2019) and make progress in ecosystem restoration (Crouzeilles et al ., 2017; Strassburg et al ., 2019). Funding, coupled with its effective use, is key to these successes.…”

Set a global target for ecosystems

“…Actions taken because of this and previous CBD targets have reduced the risk of extinction for many species, although direct links are hard to prove. For example, conservation efforts over the past 30 years have helped to cut the extinction rate of endangered birds by at least 40%, according to one analysis 3 . Previously endangered populations that are now growing include the Seychelles magpie-robin (Copsychus sechellarum) and a Brazilian parrot called Lear's macaw (Anodorhynchus leari).…”

iucn_sim: A new program to simulate future extinctions based on IUCN threat status

“…To the best of our knowledge, there are two key elements that are usually not incorporated when using IUCN status data for future extinction predictions: generation length and expected changes in conservation status (but see Monroe et al 2019).…”

“…While many previous studies have applied the IUCN-based extinction probabilities (criterion E) outlined above to model extinction risks, a recent study by Monroe et al (2019) has presented an alternative approach, avoiding these probabilities altogether. Instead Monroe et al (2019) modeled extinction risks based on observed transitions of species to the statuses EW or EX, which they then applied to model future biodiversity losses.…”

“…In this study we contrast different variations of both approaches, to which we refer to hereafter as "critE EX mode" (approach based on IUCN criterion E extinction probabilities, sensu Mooers et al 2008) and "empirical EX mode" (approach based on historic transitions towards statuses EW/EX, sensu Monroe et al 2019). We add improvements to both approaches, including the incorporation of GL data for the critE EX mode and the consideration of possibly extinct taxa in the empirical EX mode.…”