Our Burning Planet

MIGRATION SECRETS

Miniature backpack traces remarkable journey of the ‘goddess of the skies’ – the European Roller

Miniature backpack traces remarkable journey of the ‘goddess of the skies’ – the European Roller
A close-up view of the solar-powered satellite tag and antenna ‘backpack’ installed on a European Roller. The solar panel is about the size of a nail on a human pinkie finger. (Photo: Jessica Wilmot)

Where do birds stop to rest during their roughly 10,000km journey between South Africa and Eurasia? BirdLife South Africa tracked two European Rollers to find out.

There are nearly 42,000 McDonald’s restaurants serving convenient takeaway meals to backpacking tourists and other hungry folk in 120 countries across the world.

But McDonald’s has never been big on catering for hungry avian travellers such as the European Roller, compelling these birds to find their own fast food during their gruelling yearly migration between South Africa and Eurasia.

So, where exactly do the birds stop to rest and grab some grubs and a beakful of water during their roughly 10,000km journey through more than a dozen countries?

These are some of the questions that researchers at BirdLife South Africa are hoping to find answers to, after fitting tiny solar-powered “backpacks” to the first batch of European Rollers which departed from South Africa recently after a five-month summer sojourn here, far from the bleak European winter.

‘Hera’ left South Africa on 30 March and arrived in Uzbekistan on 15 May – completing a journey of about 10,500 km in six weeks (including a seven-day stopover in Somalia to rest and recuperate midway). The tracking record for ‘Royal Wasi’, another European Roller tagged in Limpopo, disappeared in Somalia. (Graphic: Jessica Wilmot / Birdlife South Africa)

Two rollers – one named Hera (the ancient Greek goddess of the skies) and Royal Wasi (a name derived from the Shangaan word for the colour blue) were captured and fitted with ultra-lightweight satellite tagging devices in the Royal Malewane section of the Greater Kruger National Park on 18 March.

Jessica Wilmot, BirdLife’s Flyway and Migrants project manager, explained that – until quite recently – tracking smaller birds via satellite has not been possible because of the inordinate weight of the transponders and batteries. 

To prevent harm or undue stress, Birdlife SA’s policy prohibits any tracking devices that exceed 3% of the bird’s body weight.

However, due to technological refinements and miniaturisation, far lighter tags have now been developed to track several of the smaller bird species.

european roller migration

A close-up view of the solar-powered satellite tag and antenna ‘backpack’ installed on a European Roller. The solar panel is about the size of a nail on a human pinkie finger. (Photo: Jessica Wilmot)

The devices fitted to Hera and Royal Wasi weigh just 3.2 grams each and are powered by tiny solar panels roughly the size of the nail on a human pinkie finger.

The packs are attached to the birds using Teflon ribbons, strapped crosswise around the chest to allow enough space for them to breathe properly and to groom.

“We want to ensure that the devices are not detrimental to their health and survival – especially during such an arduous journey,” says Wilmot, noting that the condition of the tagged birds is checked carefully beforehand under the supervision of a vet.

Hera set off first, on 30 March, and was tracked almost daily until she arrived in Uzbekistan in central Asia on 15 May – a distance of roughly 10,500km as a roller flies.

The data suggests that Hera flew somewhere between 300-500km a day – excluding a month-long stopover in Somalia to rest and refuel.

european roller migration

Craig Nattrass (left) and wildlife tracker Joseph Gumede watch proceedings as wildlife vet Bart Gazendam prepares to release one of two European Rollers as part of a research project by BirdLife South Africa. (Photo: Lourenço Alfonso / Royal Malewane)

european roller migration release

Craig Nattrass releases a European Roller that was captured and tagged earlier this year to allow researchers to track its migration route. (Photo: Lourenço Alfonso / Royal Malewane)

Apart from being roughly halfway home, Somalia is also located on the Horn of Africa and is the last spot of dry land before the bird embarks on a 400km non-stop flight over the Arabian Sea to reach Yemen.

After that, Hera had to undertake a second ocean crossing from Oman to Pakistan before returning safely to her traditional breeding grounds in central Asia.

“The tracking record shows that she set off to cross the Gulf of Oman at night – possibly because it is so hot in the Middle East during the day.  After leaving Somalia, Hera flew almost 2,500km over two days before reaching Pakistan.”

Sadly, Royal Wasi was not so lucky.

This bird left South Africa on 10 April, but the tracking signal disappeared abruptly a few weeks later on the Horn of Africa.

The researchers can only speculate about whether Royal Wasi was killed by avian or human predators – or perhaps the tag simply stopped working.

Wilmot says that one of the main reasons BirdLife SA selected the European Roller for this project is the recent significant decline in the number of these birds.

“Global migratory bird populations are in decline and the European Roller is one such bird. In just 15 years, the population has declined by more than 30%, with records of local and national extinctions throughout Europe.”

european roller migration wing

The bright blue wing feathers of a European Roller. (Photo: Lourenço Alfonso / Royal Malewane)

Birdlife notes that this charismatic bird, with electric blue wing feathers, acts as a flagship species for other migratory birds.

Read more in Daily Maverick: ‘Devastating’ death of dozens of migrating birds across SA points to coming climate change havoc — experts

According to the United Nations Environment Programme, migratory birds often time their migrations to align with insect abundance. Rollers also depend mainly on insects for food during migration stops and for breeding success and feeding their young.

However, the stark reality uncovered over recent years is that insect populations are declining, correlating with a decline in bird species reliant on insects for survival

An analysis in the journal Science has also revealed an average 9% global decline in terrestrial insect abundance per decade.

Apart from insect declines linked to pesticides, several bird species have also lost access to adequate food and habitat due to the expansion of farming land. Some birds are also vulnerable to subsistence food trappers during migration.

Wilmot says BirdLife is hoping to fit satellite tags to another five European Rollers early next year and to fit identification rings to the legs of another 50 of these birds while they are in South Africa.

However, such projects are expensive, with satellite tags costing about R47,000 each, along with data tracking fees of around R1,400 per bird per month. DM

For more information, contact [email protected]

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