The Brenton Blue Butterfly
Once saved from extinction, South Africa’s Brenton blue butterfly faces an uncertain fate after the devastating 2017 Knysna fire wiped out its last known habitat. Years of conservation efforts were undone in hours, despite researchers’ warnings of escalating climate dangers – wildfire risk.
The Brenton blue butterfly, listed as critically endangered and possibly extinct, is a rare and unique butterfly which occurred at two known localities, but is now extinct at one in Nature’s Valley and likely extinct at the other, the Brenton Blue Butterfly Reserve (BBBR) near Knysna.
Much work and public campaigning was done to secure the butterfly’s survival amid threats to its habitat since the 1990s, and the establishment of the BBBR, but researchers believe that the 2017 Knysna fire may have resulted in the extinction of the species.
The Brenton blue butterfly, also known as Orachrysops niobe. (Photo- J Bode and CapeNature)
The Lepidopterists’ Society of Africa (LepSoc Africa) President Lynn Katsoulis told Daily Maverick that there was still a very small chance that undiscovered populations of the Brenton blue still exist in the wild. Several people have looked for it and rewards have been offered, but it has not been seen since the fire.
“Wanted Alive” posters were shared by the Brenton Blue Trust in 2019 with rewards up to R20,000 to the first person, group or organisation that discovered another place where the Brenton blue butterfly was breeding following the destruction of the BBBR in the 2017 Knysna fire.
No one has yet been successful, but there is still hope among stakeholders that the Brenton blue is not lost forever.
“The devastating effects of the 2017 Knysna fire were predicted by the researchers, but no one could have foreseen that a fire of such magnitude could arise. This was one of the early portents of what could happen to biodiversity and human populations during the Anthropocene – an era of accelerating climate change caused by anthropogenic activities,” said Dave Edge, the LepSoc Africa’s custodian of the butterfly, in his 2024 review of the species.
Campaign to save the Brenton blue
According to Edge, the Brenton blue butterfly became famous in the 1990s with the LepSoc Africa campaign to prevent its imminent extinction because of the development of a luxury housing estate at Brenton-on-Sea on the southern coast of South Africa.
In the 1990s, the butterfly was already facing extinction because of bush encroachment and overgrowth from exotic plants, as well as runaway fires, prolonged drought, loss of genetic diversity and climate change.
But LepSoc Africa’s campaign gained support from national and international NGOs as well as the South African public, and pressure mounted on the national government to intervene.
This eventually led to the BBBR in Knysna, to protect the butterfly with the status of a Special Nature Reserve. This was proclaimed in 2003 with CapeNature as the management authority. Management is overseen by the Brenton Blue Butterfly Management Committee, with representation by the Brenton Blue Trust.
CapeNature told Daily Maverick that its role in active management was reserve infrastructure maintenance, expansion of the protected area through stewardship, firebreak maintenance and creation in the expanded areas, and alien clearing. The Brenton Blue Trust, through Edge, focused on monitoring, research, awareness and supported CapeNature’s activities.
Following research on its ecology by Edge, careful management of the BBBR increased the adult population to 50-250 individuals per brood.
Edge said that an intensive research project was conducted from 2000-2005, uncovering the butterfly’s unusual ecological requirements, including its caterpillar’s habit of feeding on the rootstock of its host plant Indigofera erecta under the protection of Camponotus baynei ants.
“The vegetation composition and dynamics, the biology of the host plant, the ant community and the population dynamics of the butterfly were also outcomes of this research. This facilitated the development of a reserve management programme, which for over 20 years seemed to ensure the butterfly’s survival,” Edge said.
Fire exclusion was practised because of the risk to the host ants, which nest in dead wood on the surface.
But despite these precautions, during the unprecedented Knysna fire in June 2017, the entire butterfly reserve was burnt, and even though some butterflies emerged in November 2017, these were the last ones seen at the BBBR.
Researchers and stakeholders believe that the 2017 Knysna fire may have resulted in the extinction of the species, although it is hoped that the larvae may persist underground.
Higher extinction rates
CapeNature told Daily Maverick there is a very small chance anything can be done about the Brenton blue butterfly as it is increasingly looking as if the species has tragically gone extinct.
“This is unfortunately a very likely event once a species is reduced to a single small population where any stochastic [random] event can be the death of the species,” they said.
The lesson to be learnt here is to, wherever possible, prevent populations from reaching the super-imperilled state that the Brenton blue butterfly ended up in.
“Extinction is a natural evolutionary process, but today’s extinction rate is at least a thousand times higher than the natural rate. The loss of a species, even ‘just a butterfly’, is a red flag because it indicates a crack in an ecosystem that humans depend on for survival,” CapeNature said.
It said habitat destruction and transformation remained the leading threats to species’ existence.
The testing of management strategies over the years has been led by Edge and has included the control of invasive alien plants, the creation and maintenance of paths through the reserve, modification of habitat to promote the growth of the host plant, and fire prevention.
CapeNature said it had also explored reserve expansion through stewardship, with one newly signed contract increasing the protected area from 1.5ha to more than 20 ha.
CapeNature was worried about the 2017 fire but said that it continued to carry out surveillance for the butterfly, its host plant and its host ant after the fire, in the hope that eggs or larvae had survived underground.
“Four butterflies were recorded after the fire in November 2017, but none have been found since then, despite regular monitoring. The host plant population is doing quite well, but there is no sign of the host ant species,” CapeNature said.
There was an attempt some years back to introduce the butterfly to the Nature’s Valley Fynbos Reserve, but the host plant population was not good enough and there were no host ants, so the attempt was unsuccessful.
Annual monitoring is still taking place and Edge has been actively searching for the butterfly at other potential sites.
The Brenton blue is still officially red-listed as Critically Endangered, and stakeholders hope that this doesn’t have to change to Extinct but said this was looking likely now unless an overlooked population was found elsewhere.
LepSoc Africa’s Katsoulis said the interdependence between several organisms that had all been affected by modern mankind had altered the habitat to a point that the butterfly could not exist.
Most insect populations are in a critical state of collapse and Katsoulis said it was far more dire than most people mentioned – largely driven by climate change, habitat loss and the consequent collapse of functional ecosystems.
“We are working towards large-scale restoration projects. If we can re-educate the masses, relatively small changes can make a profound difference and mitigate a large proportion of the ecosystem collapse we are all driving,” Katsoulis said.
Jeremy Dobson has been championing the South African National Biodiversity Institute’s (Sanbi’s) research project on butterflies in the National Botanical Gardens to determine if there are any long-term trends.
Dobson told Daily Maverick that most people believed butterfly abundance and diversity had reduced drastically in South Africa over the past 20 years, but they had no quantitative data to support this.
However, the botanical gardens butterfly monitoring is an attempt to redress this. The project has been active for only four seasons and it’s probably too early to draw many conclusions, but at least they have an ongoing and quantifiable monitoring project in place.
“I believe overseas butterfly monitoring programs such as eBMS have provided compelling evidence that climate change (and habitat transformation) are negatively impacting insect abundance. In South Africa, we aren’t there yet, but at least we’ve started,” Dobson said.
The Brenton blue butterfly, also known as Orachrysops niobe.
(Photo- J Bode and CapeNature)
