- A study shows birds like the bateleur, martial eagle and secretary bird, found in South Africa, face population declines.
- The conversion of natural habitats to farmland is the biggest cause of bird population declines worldwide, a researcher says.
- Rates of decline are more than twice as high in unprotected areas, and researchers call for expanding protected areas.
- For climate change news and analysis, go to News24 Climate Future.
African birds like the bateleur, martial eagle and secretary bird - found in South Africa - face drastic population declines, a new study shows.
The research, published in the journal Nature Ecology & Evolution, showed that 88% of the 42 raptor or bird species examined had declined to some degree. It also showed that 69% had declined at a rate considered to be at risk of extinction, based on criteria used by the International Union for Conservation of Nature (IUCN).
The conversion of natural habitats to farmland is a major driver of the declining bird populations worldwide. This applies to many bird species in Africa, said study author Dr Phil Shaw.
"The conversion of wooded habitats to agricultural land is more damaging to biodiversity than any other human activity and poses the greatest extinction risk to birds worldwide," the paper read.
Projections indicate that the human population on the African continent is expected to double by 2058, and this will also increase demands on land for grazing, growing crops and even energy. This is expected to "amplify" the existing pressures on protected areas where birds and other natural ecosystems are found.
Other threats to Africa's birds include the loss of their prey, shooting, trapping and poisoning of birds, unintentional poisoning, electrocution and collision with energy infrastructure like wind turbines and killing for food or belief-based uses. These threats are more prominent in unprotected areas.
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In reaching findings, the researchers measured the changes in the amounts of 42 bird species observed in surveys conducted in Niger, Burkina Faso, Mali, northern Cameroon, Kenya and Botswana. The results that were analysed were taken from four published studies - in which other researchers had counted the numbers of birds seen while driving along roads and transects between 1969 and 1995 and from 2000 to 2020.
The study found that birds in West Africa faced sharper declines than anywhere else on the continent.
The study also found that species in unprotected areas faced larger declines - more than twice - that of birds found in protected areas. For this reason, the researchers advocated strongly for the expansion of conservation areas and a strengthening of their management.
"Although many PAs are considered to be failing or deteriorating, well-managed sites form a critical refuge for the continent's declining raptor populations," the study read.
Shaw reiterated these views:
The protected area network needs to be expanded and strengthened. Rates of decline were more than twice as high on unprotected land, and we suggest that many large raptor species will have disappeared from much of Africa's unprotected land by the second half of this century. Currently, protected areas account for just 14% of Africa, and the goal (agreed at the UN Convention on Biological Diversity - COP15) is to increase this to 30% by 2030.
Shaw shared that birds of particular risk include the martial eagle, the bateleur, the secretary bird and the African hawk-eagle.
"All four have suffered declines since the 1970s in two or more regions of Africa and are resident in South Africa," said Shaw. He, however, pointed out that a citizen science project in South Africa has led to an increase in the numbers of the African hawk-eagle between 2008 and 2021.
The martial eagle, bateleur and secretary bird are classified as endangered, while the African hawk-eagle is considered of least concern, according to the IUCN.
Among the limitations of the research is that it only accounts for 40% of Africa's diurnal (active during the day) species. "Many of those we were unable to include were forest-dwelling species, whose trends are likely to have differed from the savanna species we surveyed," Shaw said. He also suggested that there is a likelihood that species dependent on forests may have "fared as badly or worse" than the species sampled for the study due to levels of deforestation.
Knock-on effects
Declining populations of predators also have knock-on effects on their prey and can disrupt the functioning of ecosystems, the study highlighted.
"In Africa, the loss of the largest and most uniquely adapted avian predators will most likely have the biggest impact on ecosystem function by limiting prey populations," Shaw reiterated.
For example, scavengers like vultures are useful in removing carcasses, and this prevents the transfer of diseases from animals to humans.
Other examples include the female martial eagles, which kill large prey like small antelope and jackals. "Smaller raptors often prey on rodents and seed-eating birds, whose populations are likely to increase in the absence of raptors, potentially causing greater damage to crops," Shaw added.
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Shaw is hopeful that the research will highlight the human-related pressures on bird populations in Africa and the need to boost the protected area network and its management.
Importantly, the study draws attention to species that are at risk of extinction - and will hopefully ensure resources are directed toward the conservation of these birds.
