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A new study, led by Oxford University, has revealed a dramatic loss of ‘wildlife power’ across Africa — the ecological energy that drives essential ecosystem functions such as nutrient cycling and seed dispersal.
The loss is placing increasing pressure on biodiversity and the human livelihoods that depend on healthy ecosystems.
According to the paper, Africa’s ecosystems are operating on less than two-thirds of the natural energy they once had.
Published in Nature and led by researcher Ty Loft, the study shows that the loss of large animals such as elephants, rhinos, and lions has dramatically reduced the ecological power that once sustained ecosystem function.
The most alarming finding is the collapse of ecosystem functions performed by Africa’s megafauna.
In this study, the researchers calculated energy flows for the 1,088 mammal and 1,955 bird species for which data were available, comprising 98 per cent of total African species excluding seabirds.
The analysis combined six major ecological datasets, including a new Biodiversity Intactness Index for Africa built with local expert knowledge.
This energy-based lens reveals not only how much biodiversity has been lost, but how that loss affects the very functioning of nature.
While large mammals have suffered the greatest declines, smaller species such as rodents and songbirds now dominate Africa's remaining energy flow.
As a result, ecosystems are increasingly powered by small animals.
Despite accounting for much less total biomass, smaller species consume a disproportionate share of energy. Historically, rodents represented 17 per cent of biomass but accounted for 31 per cent of energy use; today, they make up 24 per cent of biomass and consume 36 per cent of energy. Passerine birds — small perching birds such as songbirds, continue to use about 8 per cent of total energy while representing only 2 per cent of biomass.
In contrast, animals weighing more than 65 kilograms now account for just 7 per cent of energy use, down from 16 per cent historically.
Historically, elephants were by far the biggest drivers of ecological energy in Africa. They once made up about 16 per cent of total bird and mammal biomass and 10 per cent of total energy flow — more than any other species.
Through their feeding, movement, and dung dispersal, they shaped landscapes and influenced how much carbon ecosystems could store. Although elephants remain ecologically vital, their influence has been greatly diminished.
As smaller species take on a growing role in regulating the movement of nutrients, water, and materials, they cannot fully replace the unique functions of large animals — such as long-distance seed dispersal or the physical reshaping of vegetation through grazing and migration.
Beyond diagnosing decline, the study also points toward solutions. Its energy-based framework offers a powerful new tool for restoration and policy, helping governments, conservationists, and businesses move beyond species counts toward metrics that capture ecosystem functionality — a more meaningful measure of true ecological recovery.