Hera the European roller’s epic migration uncovers new flight paths for bird conservation

More than 10 000km in just two months. That’s the astonishing distance that Hera, a European roller tagged by BirdLife South Africa, flew to get to her breeding grounds in Uzbekistan. 

The perilous journey of this Afro-palearctic migrant is helping the bird conservation organisation uncover the marvels of migration for this colourful summer visitor to South Africa.

In March, Hera was one of two individuals tagged with tiny, solar-powered satellite trackers through BirdLife South Africa’s European roller monitoring project, which works to expand understanding of their migratory routes. The birds were also ringed with unique colours.  

The data collected from satellite tags allows researchers such as Jessica Wilmot, the flyway and migrants project manager, to map the full migration cycle of the birds. This helps to identify critical habitats and potential threats along their flyways. 

Hera, which means goddess of the skies, is a fitting name for the bird, which weighed just 1.59g when the technology was fitted by a donor of the project, Wilmot said. 

“She travelled along the east coast of Africa. From Limpopo, she went into Mozambique, and then stuck to the coast, until she got to Somalia where she spent about a month, slowly making her way to the Horn of Africa. And then when she got there, she crossed the Arabian Sea and crossed the ocean again to the coast of Pakistan, travelled to Afghanistan, was there for about a week, and then travelled to Uzbekistan.” 

According to BirdLife South Africa, Hera’s migration along the Eastern African-Eurasian Flyway is not only a “marvel of endurance” but also a symbol of ongoing efforts to protect migratory birds and their fragile ecosystems. 

“Hera really is pioneering the route that she is flying because we didn’t know,” Wilmot said. “And generally, depending on where they breed, migratory birds use different flyways but there has never been a recorded route of birds travelling within this flyway. It’s very exciting … and a first for South Africa.”

World Migratory Bird Day was marked on Saturday, under the theme “Protect Insects, Protect Birds”. 

Hera’s extraordinary journey is “shining a light on the interconnectedness of species and ecosystems”, BirdLife SA said.

Insects are a critical food source for many migratory birds, including European rollers like Hera, it said. 

“As insect populations decline because of habitat destruction, pesticide use and climate change, birds face greater challenges in completing their long migrations. Hera’s journey is not just about survival; it’s a story of resilience, hope and the incredible natural processes that sustain life across borders.” 

The satellite tags weigh a mere 3.2g, to ensure that the research doesn’t interfere with a bird’s migration and mating success. 

“We don’t want to influence its fitness to get to its breeding ground and back because that’s counterintuitive to the research that we’re trying to do,” Wilmot pointed out.

Despite their global classification as of least concern, European rollers are regionally listed as near threatened, with populations declining since the 1970s, with records of local and national extinctions throughout Europe.

One of the main aims of the project is to gain a better understanding of the migration of European rollers and identify key stop-over sites they use from within their overwintering sites. This can be used to secure additional key habitats for this species and to understand some of the threats faced at the sites. 

South Africa was identified as an important country along the migration route, BirdLife South Africa said. Much of the research and conservation work on European rollers has traditionally focused on their breeding grounds in Europe.

“Expanding our monitoring and tracking efforts to Southern Africa will deepen our understanding of their overwintering behaviour and potential threats, thereby ensuring our protection efforts include all of their life stages.

“With Hera staying in Somalia for a month, we can deduce that, at least for a month, that site was very important,” Wilmot added. “We would need her to complete the migration at least twice to confirm that this is the route she flies annually and those are the sites that she is dependent on.”

Understanding which sites are important is important for organisations involved in bird conservation because, without that understanding, “we really won’t know where to put our resources or which stakeholders to work with”.

Hera is in India at the moment and the researchers said they look forward to watching what route she takes to return to South Africa in the coming weeks.  

“The last point [GPS location] we’ve got was on 29 July on the coast of India … and we suspect that feathers have grown over the solar panel so it’s not charging very well … We’re just hoping that, when she starts migrating back, the feathers will shift and it’ll be able to charge enough and get another point.”

There are many risks involved in tagging birds. For Wilmot, “it’s terrifying” deploying the tags and then waiting for an update. “And then it doesn’t come and then you think, ‘Oh gosh has the tag failed, has the bird been predated?’ You really feel for the individuals.” 

That was the case with the other individual European roller tagged with Hera, Royal Wasi, a name derived from the Shangaan word for the colour blue. “When it got to the Horn of Africa, we lost transmission. We haven’t got any since, so we assume that either the bird was predated or the tag failed …. Tag failure is a risk that we will probably have to contend with again.”

Statistically, the project needs to deploy more satellite tags to prove that Hera’s is the route that the migrating European rollers fly. The plan is to deploy five more in February. 

The technology is not cheap. Imported from New Zealand, the satellite tags alone cost R53 000, while the satellite data fees for a two-year span amount to R33 000. Fundraising is constant, Wilmot added.

“We are using Hera as an ambassador. Imagine what else we can do, and what more we can do, if we deploy more tags.”