Secretarybirds and the Overberg: An unusual relationship
The Overberg truly bucks the trend when it comes to Secretarybirds. Despite a landscape here that is not normally preferred by these threatened birds, they still manage to forage and breed here, with seemingly relative success.
However, this is not the case across all of South Africa – nor even Africa. This charismatic bird of prey is endemic to the open landscapes of Sub-Saharan Africa and is the only member of its family, Sagittariidae, which is found nowhere else on earth. But according to BirdLife South Africa in a recent webinar called Conservation Conversations, over the past 30 years, 94% of Secretarybirds in East Africa have disappeared. Similarly, the birds are believed to be all but locally extinct in West Africa.
In South Africa, 75-80% of our Secretarybirds have also disappeared over the last three decades.
In fact, it’s believed that fewer than 10 000 Secretarybirds remain today.
That makes it all the more important to protect these extraordinary birds.
Secretarybirds prefer open landscapes and thrive in grasslands. According to 2018’s National Biodiversity Assessment, 60% of grasslands in South Africa had been lost by 2014 – 40% of which is regarded as irrecoverable.
The Overberg, however, offers an exception to the rule. This area, along with the Swartland, used to be dominated by natural Renosterveld vegetation that has since largely been replaced by agricultural fields for grain production. Nevertheless, Secretarybirds continue living in these areas, despite the relatively little remaining veld available to them, and make use of these agricultural landscapes where they can.
Furthermore, about 62% of buffers zones found around known Secretarybirds’ foraging areas are dominated by agricultural and forestry activities. This means that the responsible management of agricultural land is vital to the conservation of this species.
The Overberg Crane Group (OCG) understands that private landowners will play an increasingly important role in wildlife protection as natural habitats continue to shrink – which is why through our partners, we work to stop habitat loss and encourage good land management.
In need of support
BirdLife South Africa established its Secretarybird Conservation Project in 2011 after the species was uplisted to Vulnerable on the IUCN Red List. Since its inception, the project has helped us understand their habitat, movements, behaviour and the threats they face.
In 2020, further declines in species populations all over Africa led to another global uplisting to Endangered, along with other raptor species. If numbers continue to drop and habitats keep shrinking, the risk of total extinction can become a reality for Secretarybirds.
The challenge is not only related to the loss of habitat on private land. Findings from the Secretarybird Conservation Project showed BirdLife South Africa that only 3,2% of the areas identified where Secretarybirds occur fell inside formally protected areas. In some cases, bird populations within protected areas, like in the Kruger National Park, were also still declining.
Dr Melissa Whitecross, Landscape Conservation Programme Manager at BirdLife South Africa, explained this during the webinar: “At the end of the day, the story that comes out of this data is that many of our large terrestrial birds are taking strain within these national parks. And that really means we need to start looking carefully at how we can conserve them beyond the formal protected area landscape.”
Other threats to Secretarybirds
Secretarybirds breed year-round, but breeding behaviour peaks from August to March. Be sure to keep an eye out during the summer for their large stick nests atop small trees or shrubs in the Overberg and be careful not to disturb the young.
For years conservationists have endeavoured to better understand what happens when these birds leave the nest after fledging, since they have a high juvenile mortality rate in the first three years of life. This research is ongoing, but they are known to be predated upon when they are young and vulnerable by predators such as larger cats and other birds of prey.
Collisions with powerlines and fences also threaten flying Secretarybirds. Over the last 20 years, more than 100 records of powerline mortalities have been recorded, said Dr Whitecross. Fence entanglements are also a big challenge, which is why wildlife-friendly fences – with a barbless top wire, and bigger spaces between wires to minimise entanglements – are currently being trialled at the Middelpunt Wetland in Mpumalanga.
Food availability and diet
With their sharp eyes and powerful legs, Secretarybirds are very successful hunters. When attacking prey, they can deliver extremely accurate blows with a force five times their own body weight.
Although they sometimes offer an impressive display for birdwatchers by hunting and eating snakes, Secretarybirds’ diet actually consists mainly of arthropods – especially locusts, grasshoppers and beetles.
However, these creatures are typically regarded as pests by farmers, and South Africa is the largest pesticide user in Sub-Saharan Africa.
Dr Christiaan Brink, Raptor & Large Terrestrial Bird Project Manager at BirdLife South Africa, explained that the use of pesticides has a direct impact on Secretarybirds’ food source.
“This is a problem, because studies indicate that overall, we expect that insect populations have declined by roughly 45% over four decades. These are quite difficult estimates to make, but all indications are that there is a large decline.”
Besides declining food availability, bioaccumulation and magnification of pesticide can be lethal to Secretarybirds, since they are at the top of the trophic scales.
This is why the OCG and our partners work with farmers to raise awareness and better understand the impact of these practices on the wildlife on and around their land.
A changing climate
In order to protect Secretarybirds, it is important for conservationists to know where they live, but it can be difficult to gather data for population monitoring.
Citizen scientists have been key in this regard by feeding data to scientists through logged sightings on platforms like BirdLasser, the South African Bird Atlassing Programme (SABAP) and Coordinated Avifaunal Roadcounts (CAR Counts). This helps researchers determine population numbers and preferred habitats.
However, establishing current habitats is not enough. In order to make sure that conservation resources are applied effectively, we have to predict how climate change will alter habitats in order to know where birds will prefer to live in the future.
An upcoming PhD study – with BirdLife South Africa researchers among the supervisors – aims to aid these predictions by determining the impacts of climate change on Secretarybirds.
Do your part in the Overberg
Help protect these extraordinary birds by reporting fence entanglements and nest sightings to the Secretary Bird Project on the BirdLife SA website to help conservationists determine where the birds breed and what challenges they face.
More on the Secretarybird.
– Conservation Conversations: Saving SA’s Secretarybirds (27 Sep 22)
Images: Sharon Brink