An African penguin on Boulders beach

63 penguins were found dead on Boulders beach in South Africa ©Paul Mannix/Flickr CC BY 2.0

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Endangered penguins stung to death by bee swarm in South Africa

Officials are investigating after 63 endangered penguins were reportedly stung to death by bees. The penguins were found dead at the Boulders breeding colony in Simonstown, South Africa. 

As investigations are still ongoing, the county's national parks agency has suggested the deaths were caused by a swarm of honeybees sometime between 16 and 17 September.

While no other dead penguins have been found since, other causes, including disease and toxins, are also being investigated.

The deaths come as a blow to conservation efforts to conserve the endangered species, which the International Union for the Conservation of Nature (IUCN) records as having a 'declining' population. African penguins have lost around half their population since the late 1970s.

In a statement released by South African National Parks (SANParks), a spokesperson said: 'The dead birds were transported to the Southern African Foundation for the Conservation of Coastal Birds (SANCCOB) for post-mortems, and biological samples were sent for disease and toxicology testing. No external physical injuries were observed on any of the birds. The post-mortems revealed that all the penguins had multiple bee stings, and many dead bees were found at the site where the birds had died. 

'Therefore, preliminary investigations suggest that the penguins died because of being stung by a swarm of Cape honeybees. A dead penguin was also found on Fish Hoek beach on Friday which the SANCCOB vet has confirmed also had multiple bee stings. 

'However, samples are still being tested for other toxicity possibilities and diseases to rule out any other potential cause.' 

Deadly attacks by honeybees like this are an extremely rare event. 

Dr Joseph Monks, a Curator of Hymenoptera at the Museum, which includes bees, says, 'It sounds like the penguins, or something else, disturbed the nest which led to the attack. The bees would have perceived a penguin damaging the nest as an attack on the food supplies of honey and pollen collected for the larvae.'

Cape honey bees

The penguins may have disturbed a nest of Cape honey bees before the attack. ©Discott/Wikimedia Commons CC BY-SA 3.0

Buzz off

The bees that are thought to have been responsible for the penguin deaths are Cape honeybees, which are native to the southern tip of South Africa. They are a subspecies of honeybees that can be found in the UK which are farmed for their honey, and are not the same as the Africanised honeybee nicknamed the 'killer bee'.

Around 10% of bees in a colony are generally guards, who are specialised in their behaviour to protect the nest from attacks.

Joseph says that the bees' venom, delivered in their stings, is 'unpleasant' but that a single sting is unlikely to cause deaths as described in this incident. Instead, bees release what is known as a sting alarm pheromone (SAP) when the nest is threatened. 

'Once a perceived attack is noted, an individual guard will enter the hive, raise its abdomen and fan its wings to waft the SAP to other individuals. Additionally, bees will be attracted when an individual stings the perceived attacker as SAP is found on the sting.

'This will attract large numbers of bees, which can result in the rather sad outcome reported.'

As more bees sting the attacker, the dose of venom builds up, which can ultimately lead to death. However, Joseph says that events like this are unusual and that most of the bees will not attack but instead buzz around the attacker in an attempt to make the perceived threat move away.

In this case, the group of penguins may have been seen as attackers. While 63 dead penguins may not seem like a lot, there are only thought to be about 3,000 penguins nesting at Boulders beach. 

Penguins on Boulders beach

African penguins have seen significant population declines in the past 40 years. ©Olga Ernst/Wikimedia Commons CC BY-SA 4.0

Population under pressure

The African penguins of the Boulders colony may be familiar to many people having featured in Netflix documentary Penguin Town which was released in June this year. The species is also frequently found in zoos and aquaria around the world as part of conservation breeding programmes.

These programmes are necessary due to 'a very rapid population decline', which has been attributed to overfishing of their native seas.  While in 1978 it is estimated there were around 80,000 pairs of African penguins, it is thought that this number has declined by almost 70% to some 21,000 pairs.

The deaths of these penguins have caused concerns that the remaining birds in the park may be unable to raise the eggs that have been laid by the now dead animals.

A spokesperson for SANCCOB said: 'Losing over 60 healthy, and most likely breeding, adult African penguins is quite a blow for the Boulders colony as the species is already in trouble. Our Rangers and SANParks will monitor the nests in the area as some of these birds would have had eggs and chicks, and one partner often can't supply sufficient food or leave the chicks alone. 

'There might be a need to rescue and hand-rear some of them so we'll keep a watchful eye, as always.'