Bees have killed 63 endangered penguins by stinging them in their eyes.
The seabirds’ dead bodies were found scattered across a beach after the brutal attack.
Scientists were baffled by what had caused the cull and suspected poisoning until they found tiny bee stings embedded around the penguins’ eyes during post mortems.
The massacre has stunned conservationists who say bees do not normally attack the birds.
They believe one of the penguins may have triggered the carnage by disturbing the honey bees’ colony at Boulders Beach, near Cape Town in South Africa.
The first sting would have released an alarm pheromone attracting others to join in the attack.
The mass deaths are a blow to conservationists battling to preserve African penguins.
The species is classified as endangered and on track for functional extinction’ by 2035 if the population decline continues.
Vet David Roberts, who examined the birds, said: “The stings were so small that we could easily have missed them all together.
“We then checked the other bodies again and found stings still embedded around the eyes in almost all of the birds. We found more than 20 stings in some individuals.”
A further beach inspection unearthed a large number of dead Cape honeybees, a species native to South Africa’s Eastern and Western Cape provinces.
Boulders Beach, part of the Table Mountain national park, is home to 1,000 breeding pairs of African penguins that have become accustomed to thousands of annual visitors to their sheltered cove in False Bay.
Penguin Town, a new eight-part series on Netflix, follows the birds’ search for mates, food and shelter.
African penguins are one of the smallest species of the seabirds.
They breed only in South Africa and neighbouring Namibia where they numbered at least 1.5 million in the early 20th Century.
The most recent count found only 2% of that population left with 13,300 pairs in South Africa and 5,500 more in Namibia.
Each bird has a unique pattern of black spots on its white chest and during the March to May breeding season males and females equally share the 40-day incubation of their eggs.
The decline in African penguin numbers has been blamed on overfishing resulting in a sharp drop in the number of sardines and anchovies available in their hunting grounds.
Jenny Cullinan, from the African wild bee institute, said the disturbance of a local colony would have triggered the attacks.
Cape honey bees are very defensive of their young and nesting sites and if aggravated they look for a nearby target to attack,” she said.
“We often see chickens, horses or dogs stung and the bees always go for soft tissue. In the case of the penguins it was their eyes and flippers. Penguins can’t move quickly so would not have been able to get away.”
One observer wrote online, “It’s like a horror movie”, while another replied, “The Birds (and The Bees).”