A new international study co-authored by a University of Pretoria (UP) conservation scientist is challenging one of the most widely cited claims in global environmental debates: that wildlife populations have declined by more than 70% over the past 50 years.
Drawing on detailed data from sub-Saharan Africa, the study’s authors argue that the narrative of uniform, catastrophic biodiversity collapse does not reflect the on-the-ground reality — and might even harm effective conservation efforts.
Published in Science Advances, the study, titled “Out of Africa Comes No Support for Global Biodiversity Catastrophes”, finds that many species often cited as emblematic of global decline are stable or increasing where they are properly protected and managed.
Referring to the widely publicised global wildlife loss claim, lead author Stuart L Pimm, extraordinary professor at UP’s Conservation Ecology Research Unit (Ceru) and the Doris Duke professor of conservation at Duke University, said: “It’s not even remotely true.”
“For example, in the [WWF] Living Planet Report 2024, the graph showing the supposed year-by-year inexorable decline in wildlife uses a little elephant as the symbol to plot the data.
“In fact, Southern Africa, by which we mean the middle of Tanzania southwards, holds 75% of savannah elephants and they are slightly more numerous than they were 25 years ago,” he said.
The study critiques global biodiversity metrics, including the Living Planet Index (LPI) and the evolving planetary boundaries for biodiversity integrity. The indices, the authors argue, are “inappropriate [and] misleading”.
“While the state of biodiversity is dire, we must separate alarmist claims based on abstract, theoretical or hypothetical conjectures from more concrete claims based on carefully documented, empirically derived evidence,” they noted, cautioning that only the latter can inform conservation practice.
Sub-Saharan Africa, where the human population has grown three-and-a-half times over the past 50 years — by far the fastest growth of any continent — and where some of the world’s most impoverished people live, provides what the researchers describe as a “stress test” for global claims of ecological collapse.
If biodiversity tipping points and planetary boundary transgressions were unfolding as dramatically as some global narratives suggest, they should be especially visible in Africa’s savannahs.
To show that the data do not support the “tipping point” and “collapse” assertions, they examined terrestrial data from Africa. Although per capita consumption in Sub-Saharan Africa might be relatively low, globalisation — the export of palm oil and other commodities to richer continents, for example — must also affect its environments.
“Surely, the transgression of the biosphere’s planetary boundaries should be most evident here, especially in African savannahs, as a 2024 report confirms and where we would expect definitive catastrophic declines in wildlife populations.”
Africa hosts numerous species, among them elephants, lions and rhinos, that are conservation icons for large organisations that fundraise to protect them. “African species constitute nearly 30% of the World Wildlife Fund’s target species.
“That said, large-bodied species are also relatively easy to count. Simply, Africa provides a unique case to test dramatic claims derived from the LPI and planetary boundary transgressions.”
Pimm’s extensive experience in the region meant he was not surprised by the findings. In southern Africa, the conservation debate was increasingly about managing abundance rather than simply preventing extinction, he noted.
“Kruger may consider culling elephants, those in Addo are on contraceptives and in Botswana there was even the threat to ship thousands abroad in response to hunting complaints.”
Pimm described sweeping claims of wildlife decline in the region as “malicious”, pointing to examples such as the recovery of South Africa’s black wildebeest from near extinction.
“These claims impugn the striking successes that South Africa and its neighbours have achieved to protect biodiversity. They are deeply offensive.”
The study highlights savannah elephants in southern Africa, where populations have increased slowly over the past 25 years and notes that short-term changes in zebra species and black rhino numbers might often reflect the difficulty of obtaining accurate counts rather than genuine population collapse.
“Almost certainly, these changes reflect the difficulty of obtaining accurate counts in some areas. Conversely, large reported declines may represent undercounts rather than population collapses.”
The authors say their reanalysis of wildlife population time series suggests that some widely cited global indices can be distorted by short or statistically weak datasets.
When longer, more robust data are examined, the picture becomes more nuanced: some species are in serious decline, particularly where poaching and habitat loss remain intense while others are stable or recovering under active conservation management.
“When we separate populations from direct pressures such as poaching and habitat loss, they are just as likely to show positive growth as decline.”
Good management has allowed populations to stabilise and sometimes increase, Pimm said. “We must learn its lessons and, as is the case for elephants, understand the complexities and challenges of doing so.”
The study also points to broader methodological weaknesses in global biodiversity indicators. The LPI, for example, primarily tracks vertebrates and contains relatively little data on plants or insects, while the planetary boundaries framework has changed definitions over time and offers limited guidance for practical conservation action.
“Catastrophism and an ever-changing narrative of global transgressions might draw attention to biodiversity loss. Nonetheless, it exposes conservation science to ‘merchants of doubt’ and detracts attention from where practical conservation action is most urgently needed.”
Broad, dramatic global narratives can overstate biodiversity decline, undermine public trust and hamper practical conservation work, especially in regions where difficult but important progress is being made.
“The challenges we face at Ceru are difficult,” Pimm said. “Having large, non-Africa based groups telling the world that Africa has made a mess of things undermines trust when it’s much more complicated than that. We are doing some things very well. We must tackle tough problems, make mistakes and celebrate success.”
The paper forms part of a broader body of work examining how biodiversity should be measured under the Kunming-Montreal Global Biodiversity Framework. This international agreement was adopted in December 2022 to halt and reverse biodiversity loss by 2030.
In a related paper in the Proceedings of the National Academy of Sciences, Pimm and co-author professor John Gittleman, the founding dean of the Odum School of Ecology at the University of Georgia, argued that the lessons of conservation science must be applied more rigorously under the global framework.
As governments and conservation organisations move to implement the global biodiversity targets, the study argues that how biodiversity decline is measured — and how it is communicated — might shape not only public perception but the future of conservation itself.
“We show that the reports of large conservation organisations connect to these targets only infrequently,” the authors wrote. “Yet, there is abundant evidence to measure the successes and failures of the conservation enterprise.
“Generally, global financial commitments are substantial and increasing. We specify improvements and continual reassessments toward protected areas, developing countries and indigenous communities.
“To achieve success, we recommend actionable plans to improve implementation leading up to and following the next CBD-COP [Convention on Biological Diversity-Conference of the Parties] meetings.”
Ceru director Dr Bernard Coetzee, who was not involved in the study, said: “I welcome research that advances evidence-based conservation metrics, which is sorely needed globally but especially so in Africa.”
Ceru, he said, was committed to strengthening conservation science capacity in Africa and contributing to global biodiversity policy debates.
The real lesson from the African data was not complacency but clarity, Pimm said. “We need to be smart in protecting more areas, connecting populations where possible, avoiding having animals in small areas behind fences.
“None of those options is easy but explaining the problems and getting support for their solutions is the way forward. Let’s celebrate our successes,” he said.
This article will be updated with comment from the Zoological Society of London once received.
A new study co-authored by a University of Pretoria conservation scientist argues that widely cited claims of catastrophic global wildlife decline may overstate biodiversity loss in Africa
