Ocean-Crossing Rollers | Seabird-Hunting Caracals | Risky Seal Food | Night Caller Unmasked
Africa-Asia Migration Route of European Rollers Tracked
Conservationists in South Africa have, for the first time, tracked the long-distance migration route of European rollers to their Asian breeding grounds.
These sky-blue insect-eating birds arrive in southern Africa during the northern hemisphere’s winter.
Two birds were captured in March in South Africa’s Kruger National Park and fitted with tiny transmitters. The transmitters weigh 3.2 grammes (less than an ounce) each, and don’t interfere with the birds’ ability to fly or breed.
Since the duo left South Africa in late March and early April, one of the birds – known to the researchers as Hera – spent nearly a month in Somalia, in the Horn of Africa.
Hera then flew across the Gulf of Aden, through Oman, and then across the Gulf of Oman to Pakistan.
“In just two days, Hera has flown more than 2,500 kilometeres (1,500 miles), much of that across an ocean,” BirdLife South Africa said in an update.
At the time of writing, the satellite tag on the other roller known as Royal Wasi hadn’t transmitted data since late April, raising fears that either the device had failed or that Royal Wasi had died en route, as many migratory birds do.
There are two subspecies of rollers that visit southern Africa. The one that Hera and Royal Wasi belong to breeds in western and central Asia.
It’s hoped that by tracing their migration route conservationists can work out ways to mitigate potential threats to the species (some populations of European rollers have declined by more than 30% in just three generations).
A European Roller in Kruger National Park | Bram ter Keurs | Wikimedia Commons
New ‘Ecotype’ of Caracal Adapts to Hunting Seabirds in South Africa
South Africa’s Cape Peninsula – which juts into the Atlantic Ocean south of Cape Town like an unsheathed claw – has essentially become an “ecological island” for a wild population of caracals.
These long-eared and short-tailed felines have been cut off from the mainland by the spread of Cape Town.
The caracals that live near the city’s edge, in the north of the 52-kilometer (32 mile-long) peninsula, prey on animals like geese and rats that flourish in and around man-made reservoirs, vineyards and parks.
But in the south, the peninsula’s rugged sandstone overlain by shrubby fynbos doesn’t sustain enough terrestrial prey for the caracals.
A new study reveals that there the caracals forage regularly along the coast to obtain at least a third of their food requirements by hunting seabirds: mostly Cape cormorants, but also occasionally African penguins.
Both species are endangered.
The scientists say that the shift in the diet of the peninsula’s caracals is sufficient to qualify them as a new “ecotype”.
Fencing off and monitoring nesting colonies of penguins and cormorants to avoid attacks by caracals will likely become more urgent.
African penguin numbers have declined from around one million breeding pairs in 1920 to just 9,900 pairs today – partly because people have overfished their anchovy and sardine prey, but also dug up the guano they once used to build nesting burrows on nearby islands.
This lack of nesting material forced the birds onto the mainland and into the jaws of predators – like caracals – they’re not adapted to avoid.
A caracal in South Africa | Leo za1 | Wikimedia Commons
When Fish Run Out, Namibian Seals Turn to Risky Food
Cape fur seals in Namibia are forced to prey on St Joseph sharks – a species of chimaera that is armed with a dagger-like spine on its back – when regular fish prey runs low.
The recent discovery of 11 seals impaled with these spines, sometimes with the St Josephs still attached, coincided with the mass die-off of seals.
Famines during September-December 2020, and August-November 2021, were possibly triggered by the periodical warming of the surface waters along the Namibian coastline that displaced the seals’ traditional prey.
The impact was enormous.
At one seal colony at Pelican Point – near the coastal city of Walvis Bay – around 10,000 seal foetuses were aborted in 2020 and many adult female seals died from malnutrition. Another 4,000-or-so miscarriages were documented in 2021.
During those same periods, seals captured by Ocean Conservation Namibia – a group that works to disentangle the animals from human detritus – were found alive but badly malnourished with the barbs of the St Josephs stuck in their necks.
In addition to those rescued, at least eight dead seals were found impaled with the spines between 2020-2023, says a new study.
The authors believe the seals’ method of tearing and shaking their prey on the surface of the water “results in the dorsal spine of the chimaera becoming lodged in the seal’s body.”
The study sheds light on what species will be targeted by seals, which are Namibia’s most prolific marine predator, if their preferred prey becomes unavailable due to future environmental shifts in this region.
A Cape fur seal in Namibia | Summer J Smentek | Wikimedia Commons
Nature Notes: A Mystery Caller
A mystery caller’s identity had been eluding me for weeks. Finally, early one morning in April, I managed to identify it.
Grabbing binoculars and my smart phone, I followed the sound into the garden in the chilly darkness of the southern African autumn.
The bird was obliging, flying from one perch to another in a ring around our yard, calling continuously. Eight short notes, rising then falling in pitch.
I followed the sound as best I could into a corner of the garden. The bird was near enough for me to record its voice clearly, though I still couldn’t see it in the dense crowns of the jacaranda trees next door.
Sensing the dawn, a pair of Heuglin’s robins flew out from their nighttime roost, saw me, braked and almost collided mid-air, then darted into a nearby shrub issuing their alarm calls: crrrr, crrrr, crrrr, crrrr. I felt like an intruder and went inside.
The recording I’d got, however, finally jogged my memory.
I remembered when I had first seen this bird and heard its call. I was 13, bird watching with my parents in a gap between two hills in eastern Zimbabwe. The owl – for that was what it was – had roosted in a large Natal fig, its evergreen leaves incongruously stark against the golden-brown hillside.
The bird landed right above our heads in the branches of a white thorn tree.
It was known back then as the barred owl. That name has since been changed to the African barred owlet on account of its diminutive size.
It’s a small beetle-eater with a big voice. Little wonder I had failed to see it, in the semi-darkness of an April morning, all these years later.
